CA1088302A - Optical system for measuring dimensions of objects - Google Patents
Optical system for measuring dimensions of objectsInfo
- Publication number
- CA1088302A CA1088302A CA276,375A CA276375A CA1088302A CA 1088302 A CA1088302 A CA 1088302A CA 276375 A CA276375 A CA 276375A CA 1088302 A CA1088302 A CA 1088302A
- Authority
- CA
- Canada
- Prior art keywords
- image
- article
- optical axis
- microscope
- edge
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/022—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness by means of tv-camera scanning
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
- G01B11/0608—Height gauges
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/22—Measuring arrangements characterised by the use of optical techniques for measuring depth
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
- G01B11/2518—Projection by scanning of the object
- G01B11/2522—Projection by scanning of the object the position of the object changing and being recorded
Abstract
ABSTRACT OF THE DISCLOSURE
A microscope-projector system is employed to image and view a transistion of light and dark on an object. The position of the shadow corresponds to the vertical position of a portion of the object, and an adjustable device is employed for adjusting the position of the microscope-projector with respect to the object. A video camera may be connected to the microscope, to project the image on a monitor. Vertical adjustment of the microscope-projector assembly enables measurement of thickness, for example, with respect ot a reference level. The scan lines of the video camera may also be employed to locate the position of the shadow to indicate the thick-ness of the object, and also to automatically readjust the position of the shadow to reference level. Electronic circuitry may also play a part to determine from transition in scan lines the horizontal dimensions of an object.
A microscope-projector system is employed to image and view a transistion of light and dark on an object. The position of the shadow corresponds to the vertical position of a portion of the object, and an adjustable device is employed for adjusting the position of the microscope-projector with respect to the object. A video camera may be connected to the microscope, to project the image on a monitor. Vertical adjustment of the microscope-projector assembly enables measurement of thickness, for example, with respect ot a reference level. The scan lines of the video camera may also be employed to locate the position of the shadow to indicate the thick-ness of the object, and also to automatically readjust the position of the shadow to reference level. Electronic circuitry may also play a part to determine from transition in scan lines the horizontal dimensions of an object.
Description
8l5 ~
This invention relates to optical measurement systems, and more in particular to a method and apparatus for optically determining thickness of objects at particular regions, as well as external dimensions of objects.
The invention is of particular interest in the determination of the thickness of metal below a score line, for example, in metal discs employed in the tops of cans. It is well known that cans are provided having score lines to permit the ready opening of areas defined by the score lines. It is, of course, essential that the depth of the scores, and more in particular, the thickness of material remaining below the scores be accurately controlled, so that the opening of the can may be readily effected, and so that adequate thickness of metal remains to ensure that the contents of the can are adequate-ly retained.
In prior art measuring systems, for example, a Bausch and Lomb Scratch Depth Gauge, the image of a wire is projected on an object, and the image of the wire is viewed through a microscope. In viewing a scratch, the image of the wire in the region of the scratch is displaced, and this displace-ment may be ascertained by means of a reticle in the microscope. The displace-ment of the image of a wire thus corresponds to the depth of a scratch on the surface of an object.
This system, while having relatively good accuracy, provides only a subjective measurement since the operator views the image in the microscope directly. Thus, the operator, being subject to fatigue, cannot continually make accurate measurements. In addition, no means are provided in this system for measuring the thickness of material lying below the bottom of the scratch.
The present invention is directed to a method and apparatus for measuring a dimension of an object along a given axis.
In accordance with the method, a visible light image of an edge having a straight portion is projected, by means of a projector, on a support surface, along a first optical axis at an acute angle to the support surface.
The projected image of the edge thereby extends normal to a plane defined by the first optical axis and a second optical axis normal to the support sur-face. The resultant image is viewed from a second optical axis by means of a viewing device. The article to be measured is placed on the support axis with the specified axis parallel to the second optical axis, such that the image of the portion of the edge extends across the article. The support surface is then displaced along a second optical axis relative to the viewing -~
device, while maintaining the relative positions of the projector and in view-ing device, until the image of the portion of the edge lies in the same position on the article relative to the second optical axis as it occupied on the support surface, so that the movement along the second optical axis is a measure of the dimension of the article to be measured.
In the apparatus in accordance with the invention, the support surface is a surface of a stage adapted to support the article, and the second surface is a surface of the article. The viewing device includes a microscope viewing assembly positioned to view the article on the stage along the second optical axis. A projector is mounted to focus a knife edge image in visible light on the article on the stage along the optical axis, so that the light-dark transition extends normal to the plane defined by the first and second axes. In addition, means are provided for relatively displacing the micro-scope viewing assembly along the second optical axis with respect to the stage, while maintaining the relative position of the microscope viewing assembly ~ ~
and the pro;ector. -
This invention relates to optical measurement systems, and more in particular to a method and apparatus for optically determining thickness of objects at particular regions, as well as external dimensions of objects.
The invention is of particular interest in the determination of the thickness of metal below a score line, for example, in metal discs employed in the tops of cans. It is well known that cans are provided having score lines to permit the ready opening of areas defined by the score lines. It is, of course, essential that the depth of the scores, and more in particular, the thickness of material remaining below the scores be accurately controlled, so that the opening of the can may be readily effected, and so that adequate thickness of metal remains to ensure that the contents of the can are adequate-ly retained.
In prior art measuring systems, for example, a Bausch and Lomb Scratch Depth Gauge, the image of a wire is projected on an object, and the image of the wire is viewed through a microscope. In viewing a scratch, the image of the wire in the region of the scratch is displaced, and this displace-ment may be ascertained by means of a reticle in the microscope. The displace-ment of the image of a wire thus corresponds to the depth of a scratch on the surface of an object.
This system, while having relatively good accuracy, provides only a subjective measurement since the operator views the image in the microscope directly. Thus, the operator, being subject to fatigue, cannot continually make accurate measurements. In addition, no means are provided in this system for measuring the thickness of material lying below the bottom of the scratch.
The present invention is directed to a method and apparatus for measuring a dimension of an object along a given axis.
In accordance with the method, a visible light image of an edge having a straight portion is projected, by means of a projector, on a support surface, along a first optical axis at an acute angle to the support surface.
The projected image of the edge thereby extends normal to a plane defined by the first optical axis and a second optical axis normal to the support sur-face. The resultant image is viewed from a second optical axis by means of a viewing device. The article to be measured is placed on the support axis with the specified axis parallel to the second optical axis, such that the image of the portion of the edge extends across the article. The support surface is then displaced along a second optical axis relative to the viewing -~
device, while maintaining the relative positions of the projector and in view-ing device, until the image of the portion of the edge lies in the same position on the article relative to the second optical axis as it occupied on the support surface, so that the movement along the second optical axis is a measure of the dimension of the article to be measured.
In the apparatus in accordance with the invention, the support surface is a surface of a stage adapted to support the article, and the second surface is a surface of the article. The viewing device includes a microscope viewing assembly positioned to view the article on the stage along the second optical axis. A projector is mounted to focus a knife edge image in visible light on the article on the stage along the optical axis, so that the light-dark transition extends normal to the plane defined by the first and second axes. In addition, means are provided for relatively displacing the micro-scope viewing assembly along the second optical axis with respect to the stage, while maintaining the relative position of the microscope viewing assembly ~ ~
and the pro;ector. -
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In order that the invention may be more clearly understood, it will now be disclosed in greater detail with reference to the accompanying drawings, wherein:
Figure 1 is a simplified illustration of an apparatus in accordance : :
with the invention;
Figure 2 is an illustration of the image of the top of the pin of Figure l; : .
Figures 3A-3C illustrates three positions of the pin of Figure l;
Figures 4A-4C are top views corresponding to Figures 3a-3c respec-tively;
Figure 6 is a view of the monitor of Figure 1 showing a centered score;
Figure 5 is a view of a monitor corresponding to Figure 1, with the shadow displaced from the center of the monitor;
Figure 7 is a view of a monitor corresponding to Figure 5, with the score distorted due to use of a worn scoring tool;
Figures 8A-8C are time diagrams illustrating scan signals corre-sponding to Figures 4a-4c, respectively;
Figure 9 is a simplified illustration of a modification of an .
20apparatus in accordance with the invention;
Figure 10 is a perspective view of the preferred embodiments of an apparatus in accordance with the invention;
Figure 11 is a view of the monitor of Figure 1 in the measurement of the diameter of a rivet;
Figure 12 is a time diagram illustrating several scan line signals ~ .
of the monitor image of Figure 11; . .
Figure 13, which follows Figure 14, is a block diagram of one ~.............................................................. ' .
--3-- . .
- :. . . .
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embodiment of a control circuit in accordance with the invention; and Figure 14 is a simplified illustration of a modification of the apparatus in accordance with the invention particularly adaptable for use with the system of Figure 13, wherein the ~ertical position of the pin is adjusted.
Referring now, to the drawings, and more in particular to Figure 1, therein is illustrated, in simplified form, an apparatus in accordance with the invention. The apparatus is comprised of a microscope 20 and a projector 21 mounted on a suitable common frame 22, the projector 21 being positioned in direct light from a suitable source 23 at an angle of abo~t 45 to the optical axis of the microscope. The projector 21 has a knife edge (not shown) therein, whereby the edge of the knife extends on a diameter of the projector, and the beam of light is focussed on a pin 24, mounted on a stage 25 as illustrated in Figure 2. It is apparent that the light beam is thus semicircular, with the knife edge defining a straight transitional edge 26. The assembly, including the microscope 20 and the projector 21 is movably mounted with respect to the stage 25 by any convenient means, such as for example, an expandable support -27 which may be adjusted, for example, by means of a crank 28. A suitable ;
guage 29 is provided, for example, coupled to the crank 28 by conventional means, to provide a measure of the differences in vertical adjustment of the -microscope and projector with respect to the stage 25. It will, of course, be understood that alternatively the stage may be moved with respect to the micro-scope and projector assembly, or the pin 24 may be separately moved with respect to the microscope and projector assembly. The microscope is directed to the ~;
upper end of the pin 24, whereby the shadow of the light beam appears at the -end of the pin. It will be apparent from the following d~scription that the projector should be oriented so that the transition 26 between the light and dark areas at the end of the pin extends cross-ways, that is, normal to the plane defined by the optical ax~s of the microscope and the axis of the light beam.
- 1~81~302 While the apparatus in accordance with Figure 1 may be employed with the operator directly viewing the image through the microscope, it is preferred to mount a video camera 30 on the microscope, the video camera being connected to a monitor 31, whereby an enlarged image is presented. The mounting of the video camera may be in accordance with conventional practice.
Figure 3A illustrates, in a simplified manner, a side view of the pin 24. The line 35 represents the transition between dark and light areas projected on the pin. In the position illustrated in Figure 3A, the transi-tion 35 extends to the center of the pin, whereby the left side 36 of the top of the pin is dark, and the right side thereof is light, the transition be-tween these areas extending diagonally across the top of the pin. Figure 4A
shows the image on the monitor corresponding to the position of Figure 3A.
It is thus apparent that the transition between the viewed light area 3~ and the viewed dark area 36' extends diametrically across the image 24' of the top of the pin 24. The shadow area 407 of course, also extends behind the pin and in a region of the stage displaced from the diametrical center of the pin.
If the pin is moved downward, or the microscope-projector assembly is moved upwardly, by a distance ~ h, as illustrated in Figure 3B, the transi-tion between the dark and light areas extends across the left edge of the pin.
The view on the monitor in this case is illustrated in Figure 4B. Similarly, as illustrated in Figure 3C, if the pin 24 is moved upwardly by a distance of ~ h, the transition between the dark and light areas extends across the right side of the top of the pin. The view on the monitor in this case is illustra-ted in Figure 4C. It is thus apparent that the position of the transition between the light and dark areas on the top of the pin provides a measure of the distance between the pin and the microscope assembly.
It should, of course, be pointed out that the projector and micro-scope are in exact focal relationship with one another, so that the transition between the dark and light areas is sharp.
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If a sufficiently high microscope power is employed, accurate measure-ments may be taken, that is, the position of the transition may be accurately determined, by optically viewing the image, employing a suitable reticle in the eye-piece of the microscope. In this case, however, the field of view would be small, as would be the depth of field and the working distance 41 between the -microscope and the top of the pin. A narrow depth of field thus permits the edge of the shadow to be out of focus, so that it is difficult to define over the field. If the working distance is short, it may be impossible to properly direct the light beam so that it falls as desired in a groove. Similarly, it may be impossible to adjust the microscope to get near some scores in an object being viewed adjacent to changes in the level of the end of the viewed object, and it may be difficult to determined where the light spot is aimed. In all cases, this type of operation requires a subjective determination of the posi-tion of the shadow against the reticle.
When a video camera and monitor is employed, however, a microscope of low power, for example, a 10 power microscope may be employed, so that a 0.0001 inch distance in the object plane become 0.001 inch on the face of the Vidicon. Therefore, if the Vidicon has a resolution of 1000 TV lines per inch, the indirect per system resolution will be 0.0001 inch. A good microscope of 10 power may be provided with a working distance of nearly two inches, thereby permitting a good overall view of the object by the operator. If the area of the video camera measuring 0.5 x 0.66 inches is displayed on the monitor, then a line 0.010 inches wide in the object plane appears about one inch wide on a nine inch diagonal monitor.
As discussed above, the present invention is particularly directed to measuring the distance between the bottom of a score on a metal sheet and the bottom of the sheet. In other words, the invention is particularly direc-ted to measuring the thickness of material remaining below the bottom of a scoreO In accordance with the invention, in order to make such a measurement, 1~883(~2 the microscope-projector assembly is first positioned, for example, by means of the crank 28, so that the transition between the light and dark areas, that is, the shadow, extends diametrically across the top of the pin. Then the object to be measured is placed on top of the pin, preferably with the length-wise dimension of the extending in the plane defined by the optical axis of the mixroscope and the axis of the projected light beam. The distance between the microscope-projector assembly and the pin is then adjusted so that the shadow at the bottom of the score returns to the center 46 of the image, whereby the distance of adjustment of the microscope-projector assembly with respect to the pin corresponds to the thickness of the material below the bot-tom of the score.
When a video camera-monitor assembly is employed, the resultant views on the monitor appear as illustrated in Figures5 and 6. Thus, Figure 5 shows the image when the object is first placed on top of the pin. In this case, it is seen that the shadow has moved to the right, and the edge 45 of the shadow corresponding to the bottom of the score is to the right of the center line 46 on the monitor. ~hen the relative vertical position of the microscope-projector assembly is adjusted as described above, the transition 45 coincides with the center 46 of the viewed image, whereby the adjustment corresponds to the thickness of the material below the score. It is of course apparent that, alternatively, the vertical position of the top of the pin may be adjusted, in accordance with the arrangement of Figure 14.
It should be noted, as an incidental benefit, that the present invention may also enable determination of the wear on a scoring tool. Thus, Figures 5 and 6 illustrate the fact that the shape of the shadow in the region of the image 47 of the grooves provide a representation of the sharpness of the edges of the score, and hence the sharpness of the scoring tool. As illustra-ted in Figure 7, however, when the scoring tool has been worn, a rounded image will be presented, so that the operator will be adyised of the necessity of replacement of a scoring tool. It should, of course, be pointed out that the invention may also be employed to measure the depth of a score. In this case, for example, the microscope-projector assembly may be initially adjusted so that the shadow on the unscored portion of the object coincides with the center of the monitor screen, and, upon downward adjustment of the microscope-projec-tor assembly, the shadow corresponding to the bottom of the score then is brought to the center of the monitor so that the vertical adjustment of the monitor corresponds to the depth of the score.
The arrangement in accordance with ~igure 1 is also adapted for electronic determination of the position of the shadow, so that it is not necessary to physically adjust the position of the microscope. For this pur-pose, a suitable electronic measuring circuit 50, to be described in greater detail in the following paragraph, may be connected to the output of the video camera. In this arrangement, measurements are made with respect to a scan line of the video camera extending through the center of the image. This line 51 is illustrated in Figure 4A-4C. The amplitudes of the signals along the corresponding scan lines, from the edge 52 of the frame are respectively in Figures 8A-8C. Thus referring to Figure 8A, a transition 53 occurs in the signal level at a time which can be designated as a reference time, that is ~ t = 0. In Figure 8B, the transition 53 has moved to the left, whereby the distance between the reference 0 position and the transition 53 is a t, this time being a measure of the displacement of the shadow. Similarly, referring to Figure 8C, the transition 53 has moved to the right, indicating a positive time displacement from the reference position. Thus, by determining the time of occurrence of the transition 53, it is possible to provide an in-dication of the relative position of the microscope with respect to the object.
The time movement of the transition 53 may be indicated digitally, for example, by providing a digital counter energized by clock pulses in the period from the left end of the scan line to the occurrence of the transition 53.
: - : . . . -~ 8302 An increase in the order of magnitude of resolution by this technique may be made simply by slowing down the particular scan line, that is, the scan line extending through the center of the object, thereby decreasing the re-quired system band width. With such a technique, systems may be provided having resolutions in the order of 20 microinches.
It should be pointed out that, since the measurements are referenced to the edge of the frame, normal drift may result in inaccuracies over a long period of time. In order to overcome this problem, suitable adjustments may be provided in the electronic circuitry. For example, periodically a reference shadow may be viewed and centered on the monitor, with the circuitry then being adjusted so that the position of the reference shadow corresponds to the -reference times zero.
It must, of course, be pointed out that thickness of the material below any portion of the score, for example, displaced from the bottom, may -also be measured by the above technique. Thus, when measurements are being made electronically, the scan line that is measured may be a scan line dis-placed from the center of the object, to extend to any desired portion of the score. If desired, the scan line along which the measurement is taken may be suitably indicated on the monitor.
Since the detector of the shadow position is a scan line from the video camera, the output of the video camera is an electric signal which has a magnitude and direction such that it may be employed automatically to posi-tion and reposition the microscope-projector assembly. Thus, as illustrated in Figure 9, a suitable Servo motor 60 is provided to adjust the positioning device 27. A control circuit 61, to be described in greater detail in the following paragraph, receives the signal from the output of the video camera for producing a control signal for the Servo motor 60. In this case, upon initiation of operation of the control circuit, the Servo motor is controlled to automatically adjust the relative position of the microscope-projector 1~88302 assembly so that the shadow along the measured scan line returns to the reference zero position. If desired, a suitable indicator 62 may be provided for keeping track of the displacement of the signal from the zero reference level. The zero reference level, in the above arrangements, conveniently corresponds to the top of the pin 24. Thus, in the arrangement in accordance with the invention, all adjustments of the system may be automatic, so that it merely requires an operator for placing the object on the pin, and for initiating the operation of the automatic circuitry.
The display of the measurement results may thus either be on the monitor or on a separate digital display device. A recording system having a cartridge disc may be employed to record all measurement results, for example, the recorder 63 illustrated in Figure 9. The recording system may thus record a data and a time, the type of the object measured, as well as an indication of the particular measuring apparatus employed and any further required inform-ation. All data may thus be retrievable on a printout, for either straight output or to be statistically analyzed, in a manner identical to that employed in compound weighting systems. The systems may also include means for record-ing a tool condition code, so that tooling changes may be anticipated. If the recording system is employed, then an off-line mode switch may permit operators to employ the system for setup or occasional checks.
A particularly practical, physical embodiment of the invention is illustrated in Figure 10. In this arrangement, a housing 70 has a lower out-wardly extending platform 71, the upper portion of the housing 70 extending over the platform 71 to define a throat 72. The monitor 73 may be provided at the top of the housing over the throat. Internally, above the throat, the housing contains the microscope-projector assembly, as well as the Servo ad-justment therefor~ and the video camera, and all of the above-described electronic circuitry. In the operation of this system, it is thereby merely necessary for an operator to place an object 74 to be measured on the platform, _ 10 --.
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and initiate the operation of the system, for example, by a start buttom 75 on the housing or a suitable foot switch. Zero alignment is a maintenance adjust-ment, and need not be performed during operation. The throat of the platform should be designed, for example, to permit examining the center of the largest object to be measured.
In a further particularly advantageous embodiment of the invention, the apparatus in accordance with the invention may also be employed to deter- -~
mine the diameter of an object, for example, the diameter of a rivet employed in a can top. In this arrangement, the rivet is positioned at the locator pin, so that an image appears on the monitor as is illustrated in Figure 11.
In this Figure, the circle 80 corresponds to the outer circumference of the rivet, the shadow appearing similarly to that in Figure 4A. In other words, the assembly is adjusted so that transition 81 between light and dark areas extends diametrically across the image of the top of the rivet. Figure 12 illustrates the signals of various scan lines of the video camera. Thus, scan line 82 corresponds to a scan line above the rivet. Scan line 83 corresponds to the first scan line across the top of the rivet. Scan line 84 corresponds to a scan at the center of the rivet, and scan line 85 corresponds to the scan at the lower-most perimeter of the rivet. Scan line86corresponds to a scan line below the rivet. It is apparent that the position of the transition of the signals of scan lines 83-85 are separated by a certain number of scan lines from the transitions of the scan lines 82 and 86, with respect to the reference edge 87 corresponding to the left edge of the frame. Suitable electronic circuitry, to be described in greater detail in the following paragraphs, is then employed to determine the number of scan lines bet~een the scan lines 82 and 86, this number corresponding to the width W of the top of the rivet, that is, the diameter of the rivet.
In taking the measurements of the type illustrated in Figures 11 and 12, the system may require a different magnification range than that employed . .
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in the measurement of thickness of material below a score. The microscope thus may be provided with a turret objective, which may be rotated depending upon the type of measurement to be taken. The locator pin 24 may also be replaceable, so that, for example, a locator pin may be employed having a form of the correct size to fit the concave inside of a rivet to be measured, so that the rivet may be centered in the field of view. Thus, in accordance with the invention, a turret may also be provided having a plurality of loca-tor pins 24 thereon, so that the correct locator pin may be employed, depend-ing upon the form of the object and the type of measurement to be taken.
Referring now to Figure 13, the control circuit 61 comprises means for identifying the center line of the frame of the video signals from the television camera. For this purpose, if the video signal from the television camera is a conventional 512 line interlaced image, a 128 line cou~ter 90 is stepped by the horizontal drive signals of the television image, and reset by the vertical drive signals of the television signal. The horizontal and vertical drive signals may, of course, be obtained from the television camera.
The vertical drive signals insert a bit in the first stage of the counter, so that, on the 128th line of the image, an output signal appears on the 128 line, that is, the center line of the image. It is, of course, apparent that a counter of different length must be employed to select the center line if the image from a television camera has a different number of lines.
The output signal from the counter 90 is connected, as an enable signal, to a comparator 91 and to a one-shot multivibrator 92.
The D.C. level of the video signal is restored by a D.C. restorer 93, and connected to one input of the comparator 91. The other input of the com-parator, which may be a type 760, is connected to the center arm of a potentio-meter 94. The ends of the potentiometer are connected between ground reference -~and a positive source of D.C. voltage, and the potentiometer is set to apply a voltage to the comparator 91 corresponding to an intermediate level between the . . , ~ ~ , . . : -1~883~2 black and white levels of the video signal. As a consequence, a sharp transi-tion occurs at the output of the comparator 91 as the video signal passes the black-white edge.
The horizontal drive signal from the television camera is also applied to the one-shot multivibrator 92, and the multivibrator is adjusted, by conventional means, to produce a transition in its output signal at the center of the scan lines. That is, the one-shot multivibrator produces a pulse of a duration equal to one-half a scan line in response to the horizontal drive signal.
The outputs of the comparator 91 and one-shot multivibrator are applied as separate inputs to a phase detector 95. The output of the phase detector is thus responsive to the sequence in which the two inflected input signals are received, whereby the output is one polarity if the inflection of the output signal of the comparator 91 is first, and is of the opposite polar-ity if the inflection of the output signal of the one-shot multivibrator is first.
The output of the phase detector 95, in the control circuit 61, may be applied to a stepper motor drive circuit 96 for controlling a s~epper motor 97 connected to control the distance between the microscope objective and the object. The drive of the stepper motor drive circuit 96 is in such a direction as to always try to make a phase difference equal to zero, between the inflec-tions of the signals applied to the phase detector 95. The mechanical coupling to the m tor is set so that each output signal from the motor drive ci~cuit 96 corresponds to a predetermined distance of movement between the object and the microscope objective, such as 1/10,000 inch.
A pulse counter 98, such as an up-down counter, is also connected to the output of the stepper motor drive 96, and a digital display device 99 is energized by the pulse counter 98. As a consequence, if the pulse counter is set to zero at a reference distance, the display 99 will indicate the distance 1C~l3830Z
between the microscope objective and the object over or under the reference distance. In a particularly advantageous distance control arrangement, for controlling the distance between the locator pin 24 and the microscope objec-tive 20, employing the control circuit of Figure 13, the locator pin 24 is mounted on the stage 25 by means of a micrometer 100, as illustrated in Figure 14. A toothed belt 101 is provided extending between a pulley 102 on the shaft of the stepper motor 9~, and a pulley 103 on the micrometer 100. In this arrangement, the level of the top of the pin 24 is thereby adjusted by the stepper motor 9~ a distance indicating visually by the indicator 99, and the projector 21 and microscope 20 are held in a fixed position. ;
In the arrangement of the invention illustrated in Figure 9, the output of the video camera is shown as being applied directly to the monitor.
In the particularly advantageous arrangement in accordance with the invention, -however, as illustrated in Figure 13, the output of the television camera is applied to the monitor by way of an adder 105. An output of the counter 90 is also applied to the adder 105, whereby the center line of the image is bright-ened so the operator can see which line is employed in the measurement. In order to adjust the brightness of the indicator line, the output of the counter 90 may be applied to the adder 105 by way of a brightness potentiometer 106.
While the invention has been disclosed and described with reference to a limited number of embodiments, it will be apparent that many variations and modifications may be made therein, and it is intended in the following claims to cover each such variation, and modification as follows within the true spirit and scope of the claims.
In order that the invention may be more clearly understood, it will now be disclosed in greater detail with reference to the accompanying drawings, wherein:
Figure 1 is a simplified illustration of an apparatus in accordance : :
with the invention;
Figure 2 is an illustration of the image of the top of the pin of Figure l; : .
Figures 3A-3C illustrates three positions of the pin of Figure l;
Figures 4A-4C are top views corresponding to Figures 3a-3c respec-tively;
Figure 6 is a view of the monitor of Figure 1 showing a centered score;
Figure 5 is a view of a monitor corresponding to Figure 1, with the shadow displaced from the center of the monitor;
Figure 7 is a view of a monitor corresponding to Figure 5, with the score distorted due to use of a worn scoring tool;
Figures 8A-8C are time diagrams illustrating scan signals corre-sponding to Figures 4a-4c, respectively;
Figure 9 is a simplified illustration of a modification of an .
20apparatus in accordance with the invention;
Figure 10 is a perspective view of the preferred embodiments of an apparatus in accordance with the invention;
Figure 11 is a view of the monitor of Figure 1 in the measurement of the diameter of a rivet;
Figure 12 is a time diagram illustrating several scan line signals ~ .
of the monitor image of Figure 11; . .
Figure 13, which follows Figure 14, is a block diagram of one ~.............................................................. ' .
--3-- . .
- :. . . .
1~8830Z
embodiment of a control circuit in accordance with the invention; and Figure 14 is a simplified illustration of a modification of the apparatus in accordance with the invention particularly adaptable for use with the system of Figure 13, wherein the ~ertical position of the pin is adjusted.
Referring now, to the drawings, and more in particular to Figure 1, therein is illustrated, in simplified form, an apparatus in accordance with the invention. The apparatus is comprised of a microscope 20 and a projector 21 mounted on a suitable common frame 22, the projector 21 being positioned in direct light from a suitable source 23 at an angle of abo~t 45 to the optical axis of the microscope. The projector 21 has a knife edge (not shown) therein, whereby the edge of the knife extends on a diameter of the projector, and the beam of light is focussed on a pin 24, mounted on a stage 25 as illustrated in Figure 2. It is apparent that the light beam is thus semicircular, with the knife edge defining a straight transitional edge 26. The assembly, including the microscope 20 and the projector 21 is movably mounted with respect to the stage 25 by any convenient means, such as for example, an expandable support -27 which may be adjusted, for example, by means of a crank 28. A suitable ;
guage 29 is provided, for example, coupled to the crank 28 by conventional means, to provide a measure of the differences in vertical adjustment of the -microscope and projector with respect to the stage 25. It will, of course, be understood that alternatively the stage may be moved with respect to the micro-scope and projector assembly, or the pin 24 may be separately moved with respect to the microscope and projector assembly. The microscope is directed to the ~;
upper end of the pin 24, whereby the shadow of the light beam appears at the -end of the pin. It will be apparent from the following d~scription that the projector should be oriented so that the transition 26 between the light and dark areas at the end of the pin extends cross-ways, that is, normal to the plane defined by the optical ax~s of the microscope and the axis of the light beam.
- 1~81~302 While the apparatus in accordance with Figure 1 may be employed with the operator directly viewing the image through the microscope, it is preferred to mount a video camera 30 on the microscope, the video camera being connected to a monitor 31, whereby an enlarged image is presented. The mounting of the video camera may be in accordance with conventional practice.
Figure 3A illustrates, in a simplified manner, a side view of the pin 24. The line 35 represents the transition between dark and light areas projected on the pin. In the position illustrated in Figure 3A, the transi-tion 35 extends to the center of the pin, whereby the left side 36 of the top of the pin is dark, and the right side thereof is light, the transition be-tween these areas extending diagonally across the top of the pin. Figure 4A
shows the image on the monitor corresponding to the position of Figure 3A.
It is thus apparent that the transition between the viewed light area 3~ and the viewed dark area 36' extends diametrically across the image 24' of the top of the pin 24. The shadow area 407 of course, also extends behind the pin and in a region of the stage displaced from the diametrical center of the pin.
If the pin is moved downward, or the microscope-projector assembly is moved upwardly, by a distance ~ h, as illustrated in Figure 3B, the transi-tion between the dark and light areas extends across the left edge of the pin.
The view on the monitor in this case is illustrated in Figure 4B. Similarly, as illustrated in Figure 3C, if the pin 24 is moved upwardly by a distance of ~ h, the transition between the dark and light areas extends across the right side of the top of the pin. The view on the monitor in this case is illustra-ted in Figure 4C. It is thus apparent that the position of the transition between the light and dark areas on the top of the pin provides a measure of the distance between the pin and the microscope assembly.
It should, of course, be pointed out that the projector and micro-scope are in exact focal relationship with one another, so that the transition between the dark and light areas is sharp.
11~8830Z
If a sufficiently high microscope power is employed, accurate measure-ments may be taken, that is, the position of the transition may be accurately determined, by optically viewing the image, employing a suitable reticle in the eye-piece of the microscope. In this case, however, the field of view would be small, as would be the depth of field and the working distance 41 between the -microscope and the top of the pin. A narrow depth of field thus permits the edge of the shadow to be out of focus, so that it is difficult to define over the field. If the working distance is short, it may be impossible to properly direct the light beam so that it falls as desired in a groove. Similarly, it may be impossible to adjust the microscope to get near some scores in an object being viewed adjacent to changes in the level of the end of the viewed object, and it may be difficult to determined where the light spot is aimed. In all cases, this type of operation requires a subjective determination of the posi-tion of the shadow against the reticle.
When a video camera and monitor is employed, however, a microscope of low power, for example, a 10 power microscope may be employed, so that a 0.0001 inch distance in the object plane become 0.001 inch on the face of the Vidicon. Therefore, if the Vidicon has a resolution of 1000 TV lines per inch, the indirect per system resolution will be 0.0001 inch. A good microscope of 10 power may be provided with a working distance of nearly two inches, thereby permitting a good overall view of the object by the operator. If the area of the video camera measuring 0.5 x 0.66 inches is displayed on the monitor, then a line 0.010 inches wide in the object plane appears about one inch wide on a nine inch diagonal monitor.
As discussed above, the present invention is particularly directed to measuring the distance between the bottom of a score on a metal sheet and the bottom of the sheet. In other words, the invention is particularly direc-ted to measuring the thickness of material remaining below the bottom of a scoreO In accordance with the invention, in order to make such a measurement, 1~883(~2 the microscope-projector assembly is first positioned, for example, by means of the crank 28, so that the transition between the light and dark areas, that is, the shadow, extends diametrically across the top of the pin. Then the object to be measured is placed on top of the pin, preferably with the length-wise dimension of the extending in the plane defined by the optical axis of the mixroscope and the axis of the projected light beam. The distance between the microscope-projector assembly and the pin is then adjusted so that the shadow at the bottom of the score returns to the center 46 of the image, whereby the distance of adjustment of the microscope-projector assembly with respect to the pin corresponds to the thickness of the material below the bot-tom of the score.
When a video camera-monitor assembly is employed, the resultant views on the monitor appear as illustrated in Figures5 and 6. Thus, Figure 5 shows the image when the object is first placed on top of the pin. In this case, it is seen that the shadow has moved to the right, and the edge 45 of the shadow corresponding to the bottom of the score is to the right of the center line 46 on the monitor. ~hen the relative vertical position of the microscope-projector assembly is adjusted as described above, the transition 45 coincides with the center 46 of the viewed image, whereby the adjustment corresponds to the thickness of the material below the score. It is of course apparent that, alternatively, the vertical position of the top of the pin may be adjusted, in accordance with the arrangement of Figure 14.
It should be noted, as an incidental benefit, that the present invention may also enable determination of the wear on a scoring tool. Thus, Figures 5 and 6 illustrate the fact that the shape of the shadow in the region of the image 47 of the grooves provide a representation of the sharpness of the edges of the score, and hence the sharpness of the scoring tool. As illustra-ted in Figure 7, however, when the scoring tool has been worn, a rounded image will be presented, so that the operator will be adyised of the necessity of replacement of a scoring tool. It should, of course, be pointed out that the invention may also be employed to measure the depth of a score. In this case, for example, the microscope-projector assembly may be initially adjusted so that the shadow on the unscored portion of the object coincides with the center of the monitor screen, and, upon downward adjustment of the microscope-projec-tor assembly, the shadow corresponding to the bottom of the score then is brought to the center of the monitor so that the vertical adjustment of the monitor corresponds to the depth of the score.
The arrangement in accordance with ~igure 1 is also adapted for electronic determination of the position of the shadow, so that it is not necessary to physically adjust the position of the microscope. For this pur-pose, a suitable electronic measuring circuit 50, to be described in greater detail in the following paragraph, may be connected to the output of the video camera. In this arrangement, measurements are made with respect to a scan line of the video camera extending through the center of the image. This line 51 is illustrated in Figure 4A-4C. The amplitudes of the signals along the corresponding scan lines, from the edge 52 of the frame are respectively in Figures 8A-8C. Thus referring to Figure 8A, a transition 53 occurs in the signal level at a time which can be designated as a reference time, that is ~ t = 0. In Figure 8B, the transition 53 has moved to the left, whereby the distance between the reference 0 position and the transition 53 is a t, this time being a measure of the displacement of the shadow. Similarly, referring to Figure 8C, the transition 53 has moved to the right, indicating a positive time displacement from the reference position. Thus, by determining the time of occurrence of the transition 53, it is possible to provide an in-dication of the relative position of the microscope with respect to the object.
The time movement of the transition 53 may be indicated digitally, for example, by providing a digital counter energized by clock pulses in the period from the left end of the scan line to the occurrence of the transition 53.
: - : . . . -~ 8302 An increase in the order of magnitude of resolution by this technique may be made simply by slowing down the particular scan line, that is, the scan line extending through the center of the object, thereby decreasing the re-quired system band width. With such a technique, systems may be provided having resolutions in the order of 20 microinches.
It should be pointed out that, since the measurements are referenced to the edge of the frame, normal drift may result in inaccuracies over a long period of time. In order to overcome this problem, suitable adjustments may be provided in the electronic circuitry. For example, periodically a reference shadow may be viewed and centered on the monitor, with the circuitry then being adjusted so that the position of the reference shadow corresponds to the -reference times zero.
It must, of course, be pointed out that thickness of the material below any portion of the score, for example, displaced from the bottom, may -also be measured by the above technique. Thus, when measurements are being made electronically, the scan line that is measured may be a scan line dis-placed from the center of the object, to extend to any desired portion of the score. If desired, the scan line along which the measurement is taken may be suitably indicated on the monitor.
Since the detector of the shadow position is a scan line from the video camera, the output of the video camera is an electric signal which has a magnitude and direction such that it may be employed automatically to posi-tion and reposition the microscope-projector assembly. Thus, as illustrated in Figure 9, a suitable Servo motor 60 is provided to adjust the positioning device 27. A control circuit 61, to be described in greater detail in the following paragraph, receives the signal from the output of the video camera for producing a control signal for the Servo motor 60. In this case, upon initiation of operation of the control circuit, the Servo motor is controlled to automatically adjust the relative position of the microscope-projector 1~88302 assembly so that the shadow along the measured scan line returns to the reference zero position. If desired, a suitable indicator 62 may be provided for keeping track of the displacement of the signal from the zero reference level. The zero reference level, in the above arrangements, conveniently corresponds to the top of the pin 24. Thus, in the arrangement in accordance with the invention, all adjustments of the system may be automatic, so that it merely requires an operator for placing the object on the pin, and for initiating the operation of the automatic circuitry.
The display of the measurement results may thus either be on the monitor or on a separate digital display device. A recording system having a cartridge disc may be employed to record all measurement results, for example, the recorder 63 illustrated in Figure 9. The recording system may thus record a data and a time, the type of the object measured, as well as an indication of the particular measuring apparatus employed and any further required inform-ation. All data may thus be retrievable on a printout, for either straight output or to be statistically analyzed, in a manner identical to that employed in compound weighting systems. The systems may also include means for record-ing a tool condition code, so that tooling changes may be anticipated. If the recording system is employed, then an off-line mode switch may permit operators to employ the system for setup or occasional checks.
A particularly practical, physical embodiment of the invention is illustrated in Figure 10. In this arrangement, a housing 70 has a lower out-wardly extending platform 71, the upper portion of the housing 70 extending over the platform 71 to define a throat 72. The monitor 73 may be provided at the top of the housing over the throat. Internally, above the throat, the housing contains the microscope-projector assembly, as well as the Servo ad-justment therefor~ and the video camera, and all of the above-described electronic circuitry. In the operation of this system, it is thereby merely necessary for an operator to place an object 74 to be measured on the platform, _ 10 --.
1~830Z
and initiate the operation of the system, for example, by a start buttom 75 on the housing or a suitable foot switch. Zero alignment is a maintenance adjust-ment, and need not be performed during operation. The throat of the platform should be designed, for example, to permit examining the center of the largest object to be measured.
In a further particularly advantageous embodiment of the invention, the apparatus in accordance with the invention may also be employed to deter- -~
mine the diameter of an object, for example, the diameter of a rivet employed in a can top. In this arrangement, the rivet is positioned at the locator pin, so that an image appears on the monitor as is illustrated in Figure 11.
In this Figure, the circle 80 corresponds to the outer circumference of the rivet, the shadow appearing similarly to that in Figure 4A. In other words, the assembly is adjusted so that transition 81 between light and dark areas extends diametrically across the image of the top of the rivet. Figure 12 illustrates the signals of various scan lines of the video camera. Thus, scan line 82 corresponds to a scan line above the rivet. Scan line 83 corresponds to the first scan line across the top of the rivet. Scan line 84 corresponds to a scan at the center of the rivet, and scan line 85 corresponds to the scan at the lower-most perimeter of the rivet. Scan line86corresponds to a scan line below the rivet. It is apparent that the position of the transition of the signals of scan lines 83-85 are separated by a certain number of scan lines from the transitions of the scan lines 82 and 86, with respect to the reference edge 87 corresponding to the left edge of the frame. Suitable electronic circuitry, to be described in greater detail in the following paragraphs, is then employed to determine the number of scan lines bet~een the scan lines 82 and 86, this number corresponding to the width W of the top of the rivet, that is, the diameter of the rivet.
In taking the measurements of the type illustrated in Figures 11 and 12, the system may require a different magnification range than that employed . .
~8830Z
in the measurement of thickness of material below a score. The microscope thus may be provided with a turret objective, which may be rotated depending upon the type of measurement to be taken. The locator pin 24 may also be replaceable, so that, for example, a locator pin may be employed having a form of the correct size to fit the concave inside of a rivet to be measured, so that the rivet may be centered in the field of view. Thus, in accordance with the invention, a turret may also be provided having a plurality of loca-tor pins 24 thereon, so that the correct locator pin may be employed, depend-ing upon the form of the object and the type of measurement to be taken.
Referring now to Figure 13, the control circuit 61 comprises means for identifying the center line of the frame of the video signals from the television camera. For this purpose, if the video signal from the television camera is a conventional 512 line interlaced image, a 128 line cou~ter 90 is stepped by the horizontal drive signals of the television image, and reset by the vertical drive signals of the television signal. The horizontal and vertical drive signals may, of course, be obtained from the television camera.
The vertical drive signals insert a bit in the first stage of the counter, so that, on the 128th line of the image, an output signal appears on the 128 line, that is, the center line of the image. It is, of course, apparent that a counter of different length must be employed to select the center line if the image from a television camera has a different number of lines.
The output signal from the counter 90 is connected, as an enable signal, to a comparator 91 and to a one-shot multivibrator 92.
The D.C. level of the video signal is restored by a D.C. restorer 93, and connected to one input of the comparator 91. The other input of the com-parator, which may be a type 760, is connected to the center arm of a potentio-meter 94. The ends of the potentiometer are connected between ground reference -~and a positive source of D.C. voltage, and the potentiometer is set to apply a voltage to the comparator 91 corresponding to an intermediate level between the . . , ~ ~ , . . : -1~883~2 black and white levels of the video signal. As a consequence, a sharp transi-tion occurs at the output of the comparator 91 as the video signal passes the black-white edge.
The horizontal drive signal from the television camera is also applied to the one-shot multivibrator 92, and the multivibrator is adjusted, by conventional means, to produce a transition in its output signal at the center of the scan lines. That is, the one-shot multivibrator produces a pulse of a duration equal to one-half a scan line in response to the horizontal drive signal.
The outputs of the comparator 91 and one-shot multivibrator are applied as separate inputs to a phase detector 95. The output of the phase detector is thus responsive to the sequence in which the two inflected input signals are received, whereby the output is one polarity if the inflection of the output signal of the comparator 91 is first, and is of the opposite polar-ity if the inflection of the output signal of the one-shot multivibrator is first.
The output of the phase detector 95, in the control circuit 61, may be applied to a stepper motor drive circuit 96 for controlling a s~epper motor 97 connected to control the distance between the microscope objective and the object. The drive of the stepper motor drive circuit 96 is in such a direction as to always try to make a phase difference equal to zero, between the inflec-tions of the signals applied to the phase detector 95. The mechanical coupling to the m tor is set so that each output signal from the motor drive ci~cuit 96 corresponds to a predetermined distance of movement between the object and the microscope objective, such as 1/10,000 inch.
A pulse counter 98, such as an up-down counter, is also connected to the output of the stepper motor drive 96, and a digital display device 99 is energized by the pulse counter 98. As a consequence, if the pulse counter is set to zero at a reference distance, the display 99 will indicate the distance 1C~l3830Z
between the microscope objective and the object over or under the reference distance. In a particularly advantageous distance control arrangement, for controlling the distance between the locator pin 24 and the microscope objec-tive 20, employing the control circuit of Figure 13, the locator pin 24 is mounted on the stage 25 by means of a micrometer 100, as illustrated in Figure 14. A toothed belt 101 is provided extending between a pulley 102 on the shaft of the stepper motor 9~, and a pulley 103 on the micrometer 100. In this arrangement, the level of the top of the pin 24 is thereby adjusted by the stepper motor 9~ a distance indicating visually by the indicator 99, and the projector 21 and microscope 20 are held in a fixed position. ;
In the arrangement of the invention illustrated in Figure 9, the output of the video camera is shown as being applied directly to the monitor.
In the particularly advantageous arrangement in accordance with the invention, -however, as illustrated in Figure 13, the output of the television camera is applied to the monitor by way of an adder 105. An output of the counter 90 is also applied to the adder 105, whereby the center line of the image is bright-ened so the operator can see which line is employed in the measurement. In order to adjust the brightness of the indicator line, the output of the counter 90 may be applied to the adder 105 by way of a brightness potentiometer 106.
While the invention has been disclosed and described with reference to a limited number of embodiments, it will be apparent that many variations and modifications may be made therein, and it is intended in the following claims to cover each such variation, and modification as follows within the true spirit and scope of the claims.
Claims (5)
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE
DEFINED AS FOLLOWS:
1. A method for measuring the dimension of an article along a specified axis comprising the steps of focusing by means of a projector a visible light image of an edge having a straight portion on a support surface along a first optical axis which is at an acute angle to the support surface such that the image of said portion of the edge extends normal to a plane defined by the first optical axis and a second optical axis which is normal to the support surface, viewing the image of said portion of the edge along the second optical axis through a viewing device, placing the article on the support surface with the specified axis parallel to the second optical axis such that the image of said portion of the edge extends across the article, displacing the support surface along the second optical axis relative to the viewing device, while maintaining the relative positions of the projector and the viewing device, until the image of the portion of the edge lies in the same position on the article relative to the second optical axis as it occupied on the support surface, whereby the movement along the second optical axis is a measure of the dimension to be measured.
2. A method according to claim 1 wherein said dimension is in the thickness direction of the article and wherein the edge image on the support surface is a knife edge.
3. A method according to claim 1 in which the dimension is the depth of material remaining beneath a scratch on the article, the second surface is the surface at the base of the scratch on the article, and the support surface supporting the article is moved in the direction of the second optical axis until the image of the edge at the bottom of the scratch is aligned to have a position in the viewing device the same as that of the first position of the edge of the article on the support surface.
4. An apparatus for measuring a dimension in accordance with the method of claim 1, in which apparatus the support surface is a surface of a stage which can support said article, and the second surface is a surface of the article, said viewing device including a microscope viewing assembly positioned to view the article on the stage along the second optical axis, and further comprising a projector mounted to focus a knife edge image in visible light on the article on the stage along the optical axis so that the light-dark transition of the image extends normal to the plane defined by the first and second optical axes, and further including means for relatively displacing the microscope viewing assembly along the second optical axis with respect to the stage means while main-taining the relative positions of the microscope viewing assembly and the projector.
5. The apparatus of claim 4 further comprising means for optically scanning the image viewed by way of said microscope viewing assembly to produce a video signal, whereby an inflection occurs in a given line of the video signal at a time corresponding to light-dark transitions of the image.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US678,059 | 1976-04-19 | ||
| US05/678,059 US4113389A (en) | 1976-04-19 | 1976-04-19 | Optical measurement system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1088302A true CA1088302A (en) | 1980-10-28 |
Family
ID=24721209
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA276,375A Expired CA1088302A (en) | 1976-04-19 | 1977-04-18 | Optical system for measuring dimensions of objects |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US4113389A (en) |
| JP (1) | JPS52128170A (en) |
| AU (1) | AU2425477A (en) |
| CA (1) | CA1088302A (en) |
| CH (1) | CH615748A5 (en) |
| DE (1) | DE2716869A1 (en) |
| DK (1) | DK171677A (en) |
| FR (1) | FR2349126A1 (en) |
| GB (1) | GB1581948A (en) |
| NL (1) | NL7704206A (en) |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4165178A (en) * | 1978-06-29 | 1979-08-21 | International Business Machines Corporation | Gap measurement tool |
| US4463600A (en) * | 1980-09-23 | 1984-08-07 | University Of Birmingham | Automatic measurement of areas |
| GB2089044B (en) * | 1980-11-19 | 1985-05-01 | Cosciani Roberto Carlo | Improvements in or relating to measuring apparatus |
| US4502785A (en) * | 1981-08-31 | 1985-03-05 | At&T Technologies, Inc. | Surface profiling technique |
| JPS6063030A (en) * | 1983-09-19 | 1985-04-11 | 株式会社肌粧品科学開放研究所 | Skin wrinkle depth method and apparatus |
| SE456976B (en) * | 1985-06-14 | 1988-11-21 | Asea Ab | PROCEDURE AND DEVICE FOR A ROBOT EQUIPMENT FOR DETERMINING THE LOCATION OF A PURPOSE |
| GB2179155B (en) * | 1985-08-13 | 1989-08-16 | English Electric Valve Co Ltd | Spatial characteristic determination |
| EP0342251A1 (en) * | 1988-05-17 | 1989-11-23 | Contour Dynamics | Apparatus and method for acquisition of 3D images |
| US4983043A (en) * | 1987-04-17 | 1991-01-08 | Industrial Technology Institute | High accuracy structured light profiler |
| GB8725705D0 (en) * | 1987-11-03 | 1987-12-09 | Cosciani R C | Optical probe |
| US4979815A (en) * | 1989-02-17 | 1990-12-25 | Tsikos Constantine J | Laser range imaging system based on projective geometry |
| US4965665A (en) * | 1989-10-25 | 1990-10-23 | At&T Bell Laboratories | 3D imaging of a substrate using perpendicular scanning directions |
| US5101442A (en) * | 1989-11-24 | 1992-03-31 | At&T Bell Laboratories | Three-dimensional imaging technique using sharp gradient of illumination |
| US5097516A (en) * | 1991-02-28 | 1992-03-17 | At&T Bell Laboratories | Technique for illuminating a surface with a gradient intensity line of light to achieve enhanced two-dimensional imaging |
| DE19642293C2 (en) * | 1996-10-14 | 1998-07-16 | Zeiss Carl Jena Gmbh | Coordinate measuring device |
| GB9701177D0 (en) * | 1997-01-21 | 1997-03-12 | Hamilton Neil C | Thickness measuring apparatus |
| JP3272998B2 (en) * | 1997-09-30 | 2002-04-08 | イビデン株式会社 | Bump height pass / fail judgment device |
| IES20010218A2 (en) * | 2000-03-09 | 2001-09-19 | Athlone Extrusions Dev Ltd | A method of testing co-extruded panels |
| US6830334B2 (en) * | 2001-07-30 | 2004-12-14 | Bausch & Lomb Incorporated | Anterior chamber diameter measurement system from limbal ring measurement |
| DE10328537B4 (en) * | 2003-06-24 | 2015-03-26 | Pixargus Gmbh | Apparatus and method for measuring the dimension of a body |
| JP6079664B2 (en) * | 2014-02-25 | 2017-02-15 | トヨタ自動車株式会社 | Apparatus for measuring surface of object to be measured and method for measuring surface thereof |
| CN114777684A (en) * | 2017-10-06 | 2022-07-22 | 先进扫描仪公司 | Generating one or more luminance edges to form a three-dimensional model of an object |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2976762A (en) * | 1957-06-11 | 1961-03-28 | Arnold L Imshaug | Depth measuring apparatus for printing plates and like articles |
| US3022578A (en) * | 1958-02-26 | 1962-02-27 | Boeing Co | Discontinuity depth gauge |
| US3187185A (en) * | 1960-12-22 | 1965-06-01 | United States Steel Corp | Apparatus for determining surface contour |
| JPS5418145B1 (en) * | 1971-06-08 | 1979-07-05 | ||
| GB1449044A (en) * | 1972-11-14 | 1976-09-08 | Kongsberg Vapenfab As | Procedures and apparatuses for determining the shapes of surfaces |
-
1976
- 1976-04-19 US US05/678,059 patent/US4113389A/en not_active Expired - Lifetime
-
1977
- 1977-04-07 CH CH447177A patent/CH615748A5/de not_active IP Right Cessation
- 1977-04-13 GB GB15314/77A patent/GB1581948A/en not_active Expired
- 1977-04-14 AU AU24254/77A patent/AU2425477A/en not_active Expired
- 1977-04-16 DE DE19772716869 patent/DE2716869A1/en not_active Withdrawn
- 1977-04-18 CA CA276,375A patent/CA1088302A/en not_active Expired
- 1977-04-18 NL NL7704206A patent/NL7704206A/en not_active Application Discontinuation
- 1977-04-18 JP JP4440977A patent/JPS52128170A/en active Pending
- 1977-04-19 FR FR7711714A patent/FR2349126A1/en active Pending
- 1977-04-19 DK DK171677A patent/DK171677A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| DE2716869A1 (en) | 1977-10-27 |
| JPS52128170A (en) | 1977-10-27 |
| GB1581948A (en) | 1980-12-31 |
| FR2349126A1 (en) | 1977-11-18 |
| NL7704206A (en) | 1977-10-21 |
| US4113389A (en) | 1978-09-12 |
| CH615748A5 (en) | 1980-02-15 |
| DK171677A (en) | 1977-10-20 |
| AU2425477A (en) | 1978-10-19 |
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