WO2004046770A1 - System for locating light sources - Google Patents

System for locating light sources Download PDF

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Publication number
WO2004046770A1
WO2004046770A1 PCT/AT2003/000348 AT0300348W WO2004046770A1 WO 2004046770 A1 WO2004046770 A1 WO 2004046770A1 AT 0300348 W AT0300348 W AT 0300348W WO 2004046770 A1 WO2004046770 A1 WO 2004046770A1
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WIPO (PCT)
Prior art keywords
lens
sensor
light
lenses
toroidal
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PCT/AT2003/000348
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German (de)
French (fr)
Inventor
Robert Kovacs
Wilfried Lutz
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Robert Kovacs
Wilfried Lutz
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Application filed by Robert Kovacs, Wilfried Lutz filed Critical Robert Kovacs
Priority to DE20320985U priority Critical patent/DE20320985U1/en
Publication of WO2004046770A1 publication Critical patent/WO2004046770A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/08—Anamorphotic objectives
    • 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
    • G01B11/002—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates
    • G01B11/005—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates coordinate measuring machines
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/02—Simple or compound lenses with non-spherical faces
    • G02B3/06—Simple or compound lenses with non-spherical faces with cylindrical or toric faces

Definitions

  • the invention relates to a device for imaging light sources through at least one optical lens on at least one light-sensitive sensor, the optics used to generate the image having at least one toroidal lens.
  • Toroidal lenses are known per se and are used in some products for focusing light [JP 11084287 A (Ricoh) and US 5 703 351 A (Meyers)]. These toroidal lenses are, in particular, spherical lenses.
  • the object of the invention is to provide a device of the type mentioned at the outset which has an improved imaging quality, in particular if the light is incident over a large angular range.
  • the lens (s) also have an aspherical shape in addition to the toroidal one.
  • Spherical, toroidal lenses can always focus along the curvature of the lens (regardless of the angle of incidence of the light), but due to the spherical shape they have the disadvantage of quickly defocusing normally on the curvature of the lens.
  • Aspherical lenses also allow a fixed focus over a large angular range, normal to the curvature of the lens. Due to the focusability in both axes, a large, spatial area can be precisely visualized.
  • the lens (s) and sensor together form an optical camera unit, which is used in particular to measure movements in space.
  • Incident light coming from a point light source is focused linearly through the toroidal, aspherical lenses from one plane onto a light-sensitive array of lines or areas, consisting of a larger number of individual sensors.
  • the angle of incidence of the plane in which the light source is located can be calculated from the individual sensors activated by the incidence of light.
  • the spatial point at which the light source is located at the measurement time can be determined with the aid of three camera units which are permanently mounted to one another. The intersection of the three measured planes results in the defined spatial point.
  • the three camera units must be in a stable and fixed position to each other during the measurement. This positioning takes place via a frame made of metal or plastic, for example.
  • the spatial position of the point light sources is measured several times a second. Changes in location can be determined from the chronological sequence of the measurements. If several light sources are attached to essential points of a body, the movement of the body can be calculated and precisely analyzed from the measured spatial coordinates and their movements.
  • the invention is illustrated by means of examples from the figures. Show it:
  • Fig. 1a - a toroidal, aspherical single lens
  • Fig. 1b - a toroidal, aspherical double lens
  • Fig. 3a inner and outer contour of a single lens
  • Fig. 5 Gaussian distribution of pixel activation on a sensor
  • Light beam Fig. 6a overall system consisting of three cameras and an aluminum frame
  • Fig. 6b overall system consisting of three cameras in an aluminum tube
  • the central element of the motion measuring system is the optics used.
  • the entire measuring system consists of a metal bar on which three special infrared cameras are mounted. Each camera consists of an infrared filter, special optics, a linear sensor and electronic evaluation electronics for data preprocessing.
  • Lens optics The camera optics consist of a single or a combination of several lenses and have the task of imaging incident light on a line. What is novel about the invention is that toroidal, aspherical lenses are used instead of conventional cylindrical lenses as the focusing optics. A toroidal, aspherical single lens and a combination of two such lenses, as are used in the measuring system, are shown in Fig. 1a) and 1b).
  • Fig. 2 illustrates the process of defocusing by cylindrical lenses at small angles of incidence. In FIG. 2 it can be seen that when the angle of incidence 1 changes slightly, the focal line 2 of the lens lifts off the sensor plane 3 and the image on the sensor is defocused.
  • the toroidal, aspherical lenses have an optimized outer and inner contour for focusing [4, 5].
  • the shapes of these contours are calculated on the basis of the ideal beam path of light through the lenses and optimized for this (description below). In this way, an almost ideal image can be achieved with only 1-2 lenses.
  • the task of this lens (s) is to focus incident light from a measuring range that is as wide an angle as possible without loss of intensity.
  • the outer and inner contours of an aspherical single lens and a double lens are shown in Fig. 3 a) and b).
  • the exact lens contours are determined on the basis of an idealized beam path through one or more lenses, i.e. calculated by two or more optically refractive areas.
  • the contours are set up as n-order polynomials with variable parameters. Assuming the ideal beam path, the number of refractive surfaces and the refractive index of the lens material, the parameters are calculated using the smallest square of error. This calculation is done numerically. With the definition of the parameters, polynomials of the nth order, which describe the lens shapes, result for the contour surfaces.
  • the combination of standard lenses can achieve a significantly improved image compared to pure cylindrical lenses.
  • no combination of existing standard lenses can achieve almost the same image quality as with mathematically optimized, toroidal, aspherical lenses.
  • the use of optics consisting of three or more toroidal, aspherical lenses increases the imaging quality of the cameras and is useful for carrying out certain, very precise measurements despite the additional effort.
  • the quality of the imaging of 1-2 toroidal lenses is sufficient for most measurements.
  • the lenses are preferably made of transparent plastic such as e.g. made of PMMA.
  • the refractive index of the material has a significant influence on the shape of the lens contours.
  • the possible plastics can be machined on the one hand mechanically by turning or milling or on the other hand in the injection molding process.
  • the surface treatment by mechanical polishing is very simple with most plastics.
  • the single lens is of the order of magnitude with outer radii of 45-65 mm and inner radii of 30-50 mm, the lens thickness is in the range 7-15 mm. Depending on the lens, the values vary in the given areas.
  • the manufacturing accuracy of the lens contours should be on the order of approximately one hundredth of a millimeter in order not to cause any aberrations.
  • a complete camera consists of a) the lens optics 6 (from one or more individual lenses), b) a lens holder, c) a light-sensitive sensor 7, d) a translucent filter glass 8 and e) a camera housing.
  • the basic structure of a camera without a housing is shown graphically in FIG. 4.
  • the task of the camera is to fix the lenses, sensor and IR filter to each other in such a way that the incident infrared light is focused on the sensor by the optics and that the individual sensors activated by the light are read out by electronics in order to calculate the measured values.
  • the IR filter only lets infrared radiation through and filters higher and lower frequency rays from the incident radiation spectrum.
  • the lenses are fixed in an adjustable lens holder.
  • the focus on the sensor can be optimized by the adjustability of the lens position.
  • the position of two or more lenses in relation to each other plays a decisive role in the quality of the image.
  • the holder enables the stepless adjustment of all lenses in three spatial coordinates and the tilting of the lenses around the three axes. After the lens positions have been set, they must remain in their respective positions so that the optical focus cannot change over time. All components are installed in an opaque camera housing to protect the sensor from disturbing ambient light.
  • the operation of the camera is outlined in Fig. 4.
  • the lens optics focus the light emitted by a punctiform light-emitting diode on a line that is normal to the line sensor.
  • ⁇ 9 between the line sensor and the light beam
  • different pixels of the sensor are activated, from which the exact angle of incidence ⁇ can be calculated.
  • the angle of incidence ß 10 which is normal to the sensor, has no influence on the measurement, only the angle parallel to the line sensor is measured.
  • the overall system can calculate the intersection from the three measured angles of incidence and thus determine the exact spatial position of a punctiform LED.
  • One of the three cameras must be rotated by 90 ° in relation to the other two.
  • the principle of the measuring system is sketched in Fig. 7.
  • Line sensors which are made up of a number of individual sensors, are mostly used as light-sensitive sensors. In order to increase the sensitivity of the camera, either wider line sensors or area sensors can be used.
  • a line sensor that can be used for example, consists of at least 1,725 individual sensors (or more) or also called pixels, of which about 10-12 pixels are activated in a Gaussian intensity distribution by the incident light of the LED marker, as is shown schematically in FIG. 5.
  • a center of gravity calculation is carried out from this distribution and the angle of incidence of the central beam is calculated exactly. This calculation of the center of gravity increases the resolution of the measuring system compared to the pure pixel resolution.
  • the resolution is about 0.1 mm at a distance of 1.2 meters, the effective measuring volume in the close range is about 10 x 2.5 x 3 m.
  • the frame rate is calculated from the sample rate divided by the number of markers. Movements of the light-emitting diodes in the room can be determined from the time course of the measurements. If the light-emitting diodes are fixed on essential points of a body, the movement of the body to be measured can be calculated from the marker movements. Linear sensors with higher sensitivity and reading speed are available on the market.
  • the three necessary cameras are firmly connected to each other on a stable bar and always have the same, fixed position to each other, to which the system is ultimately calibrated.
  • the entire measuring system can be pre-calibrated by keeping the three cameras in the same position.
  • the given calibration data are automatically loaded into the system each time the program is started. 6 a) and b) the entire measuring system together with three camera units is shown in two variants. Each camera measures the angle of incidence from one plane, the intersection of the three planes defines the spatial point of the radiating light-emitting diode, as shown in FIG. 7.
  • toroidal, aspherical lenses in a motion measuring device enables the use of linear sensors without loss of quality.
  • Either two surface sensors or three linear sensors are required to measure three-dimensional movements.
  • Even the simplest linear sensors can be read very quickly, which means that the speed of the entire measuring device with linear sensors increases accordingly, in contrast to those with surface sensors.
  • the entire measuring system has opening angles of +/- 45 degrees and +/- 15 degrees with a system width of 1.2 meters. This results in a measuring range of 3 x 3 meters in the room at a distance of approx. 3.5 meters from the system.
  • linear sensors means that the amount of data is much smaller than with area sensors, which minimizes the effort involved in data processing. Therefore, the real-time capable measuring system can be operated without its own plug-in card.

Abstract

The invention relates to a system for reproducing light sources by means of at least one lens on at least one photosensitive sensor. The inventive system for carrying out the reproduction comprises at least one toroidal lens. Aside from the toroidal shape, the lens/the lenses are embodied in an aspheric shape.

Description

EINRICHTUNG ZUR LOKALISATION VON LICHTQUELLEN LOCALIZATION OF LIGHT SOURCES
Die Erfindung betrifft eine Einrichtung zur Abbildung von Lichtquellen durch mindestens eine optische Linse auf wenigstens einen lichtempfindlichen Sensor, wobei die zur Erzeugung der Abbildung verwendete Optik mindestens eine toroidale Linse aufweist.The invention relates to a device for imaging light sources through at least one optical lens on at least one light-sensitive sensor, the optics used to generate the image having at least one toroidal lens.
Toroidale Linsen sind an sich bekannt und werden in einigen Produkten zur Fokussierung von Licht eingesetzt [JP 11084287 A (Ricoh) und US 5 703 351 A (Meyers)]. Bei diesen toroidalen Linsen handelt es sich im speziellen um sphärische Linsen.Toroidal lenses are known per se and are used in some products for focusing light [JP 11084287 A (Ricoh) and US 5 703 351 A (Meyers)]. These toroidal lenses are, in particular, spherical lenses.
Aufgabe der Erfindung ist eine Einrichtung der eingangs genannten Gattung zu schaffen, die eine verbesserte Abbildungsqualität aufweist, insbesondere wenn das Licht über einen großen Winkelbereich einfällt.The object of the invention is to provide a device of the type mentioned at the outset which has an improved imaging quality, in particular if the light is incident over a large angular range.
Dies wird erfindungsgemäß dadurch erreicht, dass die Linse(n) neben der toroidalen auch eine asphärische Form aufweist (aufweisen).This is achieved according to the invention in that the lens (s) also have an aspherical shape in addition to the toroidal one.
Sphärische, toroidale Linsen können zwar entlang der Linsenkrümmung immer fokussieren (unabhängig vom Einfallswinkel des Lichtes), haben aber durch die sphärische Form den Nachteil, normal auf die Linsenkrümmung rasch zu defokussieren. Asphärische Linsen ermöglichen auch normal zur Linsenkrümmung einen festen Fokus über einen großen Winkelbereich. Durch die Fokussierbarkeit in beiden Achsen kann ein großer, Raumbereich präzise optisch abgebildet werden.Spherical, toroidal lenses can always focus along the curvature of the lens (regardless of the angle of incidence of the light), but due to the spherical shape they have the disadvantage of quickly defocusing normally on the curvature of the lens. Aspherical lenses also allow a fixed focus over a large angular range, normal to the curvature of the lens. Due to the focusability in both axes, a large, spatial area can be precisely visualized.
Linse(n) und Sensor bilden zusammen eine optische Kameraeinheit, die im speziellen zur Vermessung von Bewegungen im Raum verwendet wird. Dabei wird einfallendes Licht von einer punktförmigen Lichtquelle kommend durch die toroidalen, asphärischen Linsen aus einer Ebene Iinienförmig auf ein lichtempfindliches Zeilen- oder Flächenarray, bestehend aus einer größeren Anzahl von Einzelsensoren, fokussiert. Aus den durch Lichteinfall aktivierten Einzelsensoren lässt sich der Einfallswinkel der Ebene errechnen, in der sich die Lichtquelle befindet.The lens (s) and sensor together form an optical camera unit, which is used in particular to measure movements in space. Incident light coming from a point light source is focused linearly through the toroidal, aspherical lenses from one plane onto a light-sensitive array of lines or areas, consisting of a larger number of individual sensors. The angle of incidence of the plane in which the light source is located can be calculated from the individual sensors activated by the incidence of light.
Wird eine punktförmige Lichtquelle, vorzugsweise eine Leuchtdiode (LED), verwendet, so kann mit Hilfe von drei zueinander fest montierten Kameraeinheiten der Raumpunkt bestimmt werden, an welchem sich die Lichtquelle zur Messzeit befindet. Der Schnittpunkt der drei gemessenen Ebenen ergibt den definierten Raumpunkt. Die drei Kameraeinheiten müssen während der Messung in einer stabilen und fixierten Position zueinander stehen. Diese Positionierung erfolgt über ein Gestell beispielsweise aus Metall oder Kunststoff. Die Messung der Raumposition der punktförmigen Lichtquellen erfolgt mehrmals in der Sekunde. Aus der zeitlichen Abfolge der Messungen können Ortsänderungen bestimmt werden. Werden mehrere Lichtquellen auf essentiellen Punkten eines Körpers befestigt, kann aus den gemessenen Raumkoordinaten und deren Bewegungen die Bewegung des Körpers errechnet und exakt analysiert werden. Die Erfindung wird anhand von Beispielen durch die Figuren erläutert. Es zeigen:If a point-shaped light source, preferably a light-emitting diode (LED), is used, the spatial point at which the light source is located at the measurement time can be determined with the aid of three camera units which are permanently mounted to one another. The intersection of the three measured planes results in the defined spatial point. The three camera units must be in a stable and fixed position to each other during the measurement. This positioning takes place via a frame made of metal or plastic, for example. The spatial position of the point light sources is measured several times a second. Changes in location can be determined from the chronological sequence of the measurements. If several light sources are attached to essential points of a body, the movement of the body can be calculated and precisely analyzed from the measured spatial coordinates and their movements. The invention is illustrated by means of examples from the figures. Show it:
Fig. 1a - eine toroidale, asphärische Einzellinse Fig. 1b - eine toroidale, asphärische DoppellinseFig. 1a - a toroidal, aspherical single lens Fig. 1b - a toroidal, aspherical double lens
Fig. 2 - Strahlengänge mit unterschiedlichen Einfallswinkeln und die resultierendeFig. 2 - beam paths with different angles of incidence and the resulting
Brennliniefocal line
Fig. 3a - Innen- und Außenkontur einer Einzellinse; Linse weist sehr flacheFig. 3a - inner and outer contour of a single lens; Lens has very flat
Außenkontur auf Fig. 3b - Innen- und Außenkonturen einer DoppellinseOuter contour on Fig. 3b - inner and outer contours of a double lens
Fig. 4 - Aufbau und Funktion der Kamera; Abb. einer LED durch eine Linse aufFig. 4 - Structure and function of the camera; Fig. Of an LED through a lens
Zeilensensorline sensor
Fig. 5 - Gaussförmige Verteilung der Pixelaktivierung auf einem Sensor durchFig. 5 - Gaussian distribution of pixel activation on a sensor
Lichtstrahl Fig. 6a - Gesamtsystem bestehend aus drei Kameras und einem AluminiumgestellLight beam Fig. 6a - overall system consisting of three cameras and an aluminum frame
Fig. 6b - Gesamtsystem bestehend aus drei Kameras in einem AluminiumrohrFig. 6b - overall system consisting of three cameras in an aluminum tube
Zentrales Element des Bewegungsmeßsystems ist die verwendete Optik. Das gesamte Meßsystem besteht aus einem Metallbalken, auf dem drei spezielle Infrarot-Kameras montiert sind. Jede Kamera besteht aus einem Infrarotfilter, einer Spezialoptik, einem Linearsensor und einer Äuswerteelektronik zur Datenvorverarbeitung.The central element of the motion measuring system is the optics used. The entire measuring system consists of a metal bar on which three special infrared cameras are mounted. Each camera consists of an infrared filter, special optics, a linear sensor and electronic evaluation electronics for data preprocessing.
Linsenoptik: Die Kameraoptik besteht aus einer einzelnen bzw. einer Kombination mehrerer Linsen und hat die Aufgabe, einfallendes Licht auf eine Linie abzubilden. Das neuartige an der Erfindung ist, dass als Fokussierungsoptik toroidale, ashphärische Linsen anstatt herkömmliche Zylinderlinsen verwendet werden. Eine toroidale, ashphärische Einzellinse und eine Kombination von zwei derartigen Linsen, wie sie im Meßsystem verwendet werden, sind in Fig. 1a) und 1b) dargestellt.Lens optics: The camera optics consist of a single or a combination of several lenses and have the task of imaging incident light on a line. What is novel about the invention is that toroidal, aspherical lenses are used instead of conventional cylindrical lenses as the focusing optics. A toroidal, aspherical single lens and a combination of two such lenses, as are used in the measuring system, are shown in Fig. 1a) and 1b).
Normale Zylinderlinsen können nur in einem sehr eingeschränkten Winkelbereich abbilden und defokussieren bei größeren Einfallswinkeln. Durch das Kombinieren mit anderen handelsüblichen Linsen kann dieses Verhalten z.T. minimiert werden. Fig. 2 veranschaulicht den Vorgang der Defokussierung durch Zylinderlinsen bei kleinen Einfallswinkeln. In Fig. 2 ist zu erkennen, dass sich bei geringfügiger Änderung des Einfallswinkels 1 die Brennlinie 2 der Linse von der Sensorebene 3 abhebt und die Abbildung auf dem Sensor defokussiert wird.Normal cylindrical lenses can only image in a very limited angular range and defocus at larger angles of incidence. By combining with This behavior can be minimized in some other commercially available lenses. Fig. 2 illustrates the process of defocusing by cylindrical lenses at small angles of incidence. In FIG. 2 it can be seen that when the angle of incidence 1 changes slightly, the focal line 2 of the lens lifts off the sensor plane 3 and the image on the sensor is defocused.
Wird zur Fokussierung eine toroidale Linse verwendet, bleibt der Fokus des Lichtstrahls auch bei größerem Einfallswinkel auf dem Zeilensensor. Bei diesem Aufbau ist der Einsatz von mehreren kombinierten Standardlinsen nicht notwendig. Die toroidalen, asphärischen Linsen haben eine zur Fokussierung optimierte Außen- und Innenkontur [4, 5]. Die Formen dieser Konturen werden anhand dem idealen Strahlengang des Lichtes durch die Linsen berechnet und dafür optimiert (Beschreibung untenstehend). Auf diese Weise lässt sich mit nur 1-2 Linsen eine annähernd ideale Abbildung erreichen. Aufgabe dieser Linse(n) ist es, einfallendes Licht ohne Intensitätsverluste aus einem möglichst weitwinkeligen Messbereich zu fokussieren. Die Außen- und Innenkonturen einer asphärischen Einzellinse und einer Doppellinse sind in Fig. 3 a) und b) abgebildet.If a toroidal lens is used for focusing, the focus of the light beam remains on the line sensor even with a larger angle of incidence. With this construction, the use of several combined standard lenses is not necessary. The toroidal, aspherical lenses have an optimized outer and inner contour for focusing [4, 5]. The shapes of these contours are calculated on the basis of the ideal beam path of light through the lenses and optimized for this (description below). In this way, an almost ideal image can be achieved with only 1-2 lenses. The task of this lens (s) is to focus incident light from a measuring range that is as wide an angle as possible without loss of intensity. The outer and inner contours of an aspherical single lens and a double lens are shown in Fig. 3 a) and b).
Die exakten Linsenkonturen werden anhand eines idealisierten Strahlenganges durch ein oder mehr Linsen, d.h. durch zwei oder mehr optisch brechender Flächen kalkuliert. Die Konturen werden als Polynome n-ter Ordnung mit variablen Parametern angesetzt. Unter Annahme des idealen Strahlenganges, der Anzahl der brechenden Flächen und des Brechungsindex des Linsenmaterials werden die Parameter anhand des kleinsten Fehlerquadrates errechnet. Diese Kalkulation erfolgt numerisch. Mit der Festlegung der Parameter ergeben sich für die Konturflächen Polynome n-ter Ordnung, welche die Linsenformen beschreiben.The exact lens contours are determined on the basis of an idealized beam path through one or more lenses, i.e. calculated by two or more optically refractive areas. The contours are set up as n-order polynomials with variable parameters. Assuming the ideal beam path, the number of refractive surfaces and the refractive index of the lens material, the parameters are calculated using the smallest square of error. This calculation is done numerically. With the definition of the parameters, polynomials of the nth order, which describe the lens shapes, result for the contour surfaces.
Anhand dieser Polynome wird jeweils ein Satz von Einzelpunkten der Konturen berechnet, die dann zur Herstellung der Linsen verwendet werden. Bei Veränderungen der Kamerageometrie müssen die Konturen entsprechend angepasst und neu berechnet werden.On the basis of these polynomials, a set of individual points of the contours is calculated, which are then used to manufacture the lenses. If the camera geometry changes, the contours must be adjusted accordingly and recalculated.
Durch die Kombination von Standardlinsen kann eine deutlich verbesserte Abbildung gegenüber reinen Zylinderlinsen erzielt werden. Es lässt sich aber durch keine Kombination vorhandener Standardlinsen eine annähernd gleiche Abbildungsqualität erzielen, wie mit mathematisch optimierten, toroidalen, asphärischen Linsen. Der Einsatz einer Optik bestehend aus drei und mehr toroidalen, asphärischen Linsen erhöht die Abbildungsqualität der Kameras und ist für die Durchführung von bestimmten, sehr präzisen Messungen trotz Mehraufwand sinnvoll. Die Qualität der Abbildung von 1-2 toroidalen Linsen ist für die meisten Messungen ausreichend.The combination of standard lenses can achieve a significantly improved image compared to pure cylindrical lenses. However, no combination of existing standard lenses can achieve almost the same image quality as with mathematically optimized, toroidal, aspherical lenses. The use of optics consisting of three or more toroidal, aspherical lenses increases the imaging quality of the cameras and is useful for carrying out certain, very precise measurements despite the additional effort. The quality of the imaging of 1-2 toroidal lenses is sufficient for most measurements.
Die Linsen sind vorzugsweise aus durchsichtigem Kunststoff wie z.B. aus PMMA gefertigt. Kunststoff ist zumeist weich und leicht zu bearbeiten, ist kostengünstig und weist im sichtbar-infraroten Strahlungsbereich einen Brechungsindex auf, der jenem von Glas entspricht [n = 1 ,52]. Der Brechungsindex des Materials hat einen wesentlichen Einfluss auf die Form der Linsenkonturen. Die möglichen Kunststoffe lassen sich einerseits mechanisch durch Drehen bzw. Fräsen oder andererseits im Spritzgussverfahren bearbeiten. Die Oberflächenbehandlung durch mechanisches Polieren ist bei den meisten Kunststoffen sehr einfach.The lenses are preferably made of transparent plastic such as e.g. made of PMMA. Plastic is mostly soft and easy to work with, is inexpensive and has a refractive index in the visible infrared radiation range that corresponds to that of glass [n = 1, 52]. The refractive index of the material has a significant influence on the shape of the lens contours. The possible plastics can be machined on the one hand mechanically by turning or milling or on the other hand in the injection molding process. The surface treatment by mechanical polishing is very simple with most plastics.
Die Einzellinse liegt im gegebenen Fall in den Größenordnungen mit Außenradien von 45-65 mm und Innenradien von 30-50 mm, die Linsendicke liegt im Bereich 7-15 mm. Je nach Linse variieren die Werte in den gegebenen Bereichen. Die Fertigungsgenauigkeit der Linsenkonturen sollte in der Größenordnung von ca. einem hunderstel Millimeter liegen, um keine Abbildungsfehler zu verursachen.In the given case, the single lens is of the order of magnitude with outer radii of 45-65 mm and inner radii of 30-50 mm, the lens thickness is in the range 7-15 mm. Depending on the lens, the values vary in the given areas. The manufacturing accuracy of the lens contours should be on the order of approximately one hundredth of a millimeter in order not to cause any aberrations.
Kamera: Eine vollständige Kamera besteht aus a) der Linsenoptik 6 (aus einer oder mehreren Einzellinsen), b) einer Linsenhalterung, c) einem lichtempfindlichen Sensor 7, d) einem lichtdurchlässigen Filterglas 8 und e) einem Kameragehäuse. Der prinzipielle Aufbau einer Kamera ohne Gehäuse ist in Fig. 4 graphisch dargestellt.Camera: A complete camera consists of a) the lens optics 6 (from one or more individual lenses), b) a lens holder, c) a light-sensitive sensor 7, d) a translucent filter glass 8 and e) a camera housing. The basic structure of a camera without a housing is shown graphically in FIG. 4.
Aufgabe der Kamera ist es, Linsen, Sensor und IR-Filter derart zueinander zu fixieren, dass das einfallende Infrarotlicht durch die Optik auf den Sensor fokussiert wird und dass die vom Licht aktivierten Einzelsensoren von einer Elektronik ausgelesen werden, um daraus die Messwerte zu errechnen. Der IR-Filter lässt nur Infrarotstrahlung durch und filtert höher- und tiefer-frequente Strahlen aus dem einfallenden Strahlungsspektrum. Die Linsen werden in einer verstellbaren Linsenhalterung fixiert. Durch die Einstellbarkeit der Linsenposition kann der Fokus auf den Sensor optimiert werden. Die Stellung von zwei oder mehr Linsen zueinander spielt eine maßgebliche Rolle bei der Qualität der Abbildung. Die Halterung ermöglicht eine stufenlose Einstellung aller Linsen in drei Raumkoordinaten und das Verkippen der Linsen um die drei Achsen. Nachdem die Linsenpositionen eingestellt sind, müssen diese in der jeweiligen Stellung bleiben, damit sich nicht der optische Fokus über die Zeit verändern kann. Alle Bauelemente werden in ein lichtundurchlässiges Kameragehäuse eingebaut, um den Sensor vor störendem Umgebungslicht zu schützen.The task of the camera is to fix the lenses, sensor and IR filter to each other in such a way that the incident infrared light is focused on the sensor by the optics and that the individual sensors activated by the light are read out by electronics in order to calculate the measured values. The IR filter only lets infrared radiation through and filters higher and lower frequency rays from the incident radiation spectrum. The lenses are fixed in an adjustable lens holder. The focus on the sensor can be optimized by the adjustability of the lens position. The position of two or more lenses in relation to each other plays a decisive role in the quality of the image. The holder enables the stepless adjustment of all lenses in three spatial coordinates and the tilting of the lenses around the three axes. After the lens positions have been set, they must remain in their respective positions so that the optical focus cannot change over time. All components are installed in an opaque camera housing to protect the sensor from disturbing ambient light.
Die Funktionsweise der Kamera ist in Fig. 4 skizziert. Die Linsenoptik fokussiert das von einer punktförmigen Leuchtdiode abgestrahlte Licht auf eine Linie, die normal auf den Zeilensensor steht. Abhängig vom Einfallswinkel α 9 zwischen Zeilensensor und Lichtstrahl werden unterschiedliche Pixel des Sensors aktiviert, aus denen der genaue Einfallswinkel α berechnet werden kann. Der Einfallswinkel ß 10, der normal auf den Sensor steht hat keinen Einfluss auf die Messung, es wird ausschließlich der Winkel parallel zum Zeilensensor gemessen. Durch die Verwendung von drei Kameras, deren Positionen zueinander fixiert sind, kann das Gesamtsystem aus den drei gemessenen Einfallswinkeln den Schnittpunkt berechnen und so die exakte räumliche Position einer punktförmigen Leuchtdiode bestimmen. Dabei muss eine der drei Kameras gegenüber den anderen beiden um 90° gedreht sein. Das Prinzip des Meßsystems ist in Fig. 7 skizziert.The operation of the camera is outlined in Fig. 4. The lens optics focus the light emitted by a punctiform light-emitting diode on a line that is normal to the line sensor. Depending on the angle of incidence α 9 between the line sensor and the light beam, different pixels of the sensor are activated, from which the exact angle of incidence α can be calculated. The angle of incidence ß 10, which is normal to the sensor, has no influence on the measurement, only the angle parallel to the line sensor is measured. By using three cameras, the positions of which are fixed to each other, the overall system can calculate the intersection from the three measured angles of incidence and thus determine the exact spatial position of a punctiform LED. One of the three cameras must be rotated by 90 ° in relation to the other two. The principle of the measuring system is sketched in Fig. 7.
Als lichtempfindliche Sensoren werden zumeist Zeilensensoren verwendet, die aus einer Reihe Einzelsensoren aufgebaut sind. Um die Empfindlichkeit der Kamera zu erhöhen, können entweder breitere Zeilensensoren oder auch Flächensensoren verwendet werden.Line sensors, which are made up of a number of individual sensors, are mostly used as light-sensitive sensors. In order to increase the sensitivity of the camera, either wider line sensors or area sensors can be used.
Ein beispielsweise verwendbarer Zeilensensor besteht aus mindestens 1.725 Einzelsensoren (oder mehr) bzw. auch Pixel genannt, von denen durch das einfallende Licht des LED-Markers etwa 10-12 Pixel in einer gaussförmigen Intensitätsverteilung aktiviert werden, wie in Fig. 5 schematisch dargestellt ist. Aus dieser Verteilung wird eine Schwerpunkts-berechnung durchgeführt und der Einfallswinkel des Zentralstrahls exakt errechnet. Mit dieser Schwerpunktsberechnung erhöht sich die Auflösung des Meßsystems gegenüber der reinen Pixelauflösung. Die Auflösung liegt bei etwa 0.1 mm bei einer Entfernung von 1.2 Meter, das effektive Messvolumen beträgt im Nahbereich etwa 10 x 2,5 x 3 m.A line sensor that can be used, for example, consists of at least 1,725 individual sensors (or more) or also called pixels, of which about 10-12 pixels are activated in a Gaussian intensity distribution by the incident light of the LED marker, as is shown schematically in FIG. 5. A center of gravity calculation is carried out from this distribution and the angle of incidence of the central beam is calculated exactly. This calculation of the center of gravity increases the resolution of the measuring system compared to the pure pixel resolution. The resolution is about 0.1 mm at a distance of 1.2 meters, the effective measuring volume in the close range is about 10 x 2.5 x 3 m.
Es können abhängig von der Art der verwendeten Zeilensensoren mindestens 1200 Samples pro Sekunde oder mehr von den drei Kameras erfasst werden. Da die LEDs seriell aufleuchten errechnet sich die Bildrate aus der Samplerate dividiert durch die Anzahl der Marker. Aus dem zeitlichen Verlauf der Messungen lassen sich Bewegungen der Leuchtdioden im Raum bestimmen. Werden die Leuchtdioden auf essentiellen Punkten eines Körpers fixiert, kann aus den Markerbewegungen die Bewegung des zu vermessenden Körpers errechnet werden. Linearsensoren mit höherer Empfindlichkeit und Auslesegeschwindigkeit werden am Markt angeboten.Depending on the type of line sensors used, at least 1200 samples per second or more can be captured by the three cameras. Since the LEDs light up in series, the frame rate is calculated from the sample rate divided by the number of markers. Movements of the light-emitting diodes in the room can be determined from the time course of the measurements. If the light-emitting diodes are fixed on essential points of a body, the movement of the body to be measured can be calculated from the marker movements. Linear sensors with higher sensitivity and reading speed are available on the market.
Keine Linse ist ideal und fehlerfrei, sodass eine exakte Vermessung der Ergebnisse nicht möglich ist. Um trotzdem genau messen zu können, werden sämtliche Systeme vermessen und eine Korrektur errechnet.No lens is ideal and error-free, so that an exact measurement of the results is not possible. In order to be able to measure precisely, all systems are measured and a correction is calculated.
Die drei notwendigen Kameras sind auf einem stabilen Balken fest miteinander verbunden und haben die immer gleiche, fixierte Position zueinander, auf die das System letztlich kalibriert wird. Durch die immer gleiche Position der drei Kameras zueinander kann das gesamte Meßsystem vorkalibriert werden. Die gegebenen Kalibrierdaten werden bei jedem Programmstart automatisch ins System geladen. In Fig. 6 a) und b) ist das gesamte Meßsystem mitsamt drei Kameraeinheiten in zwei Varianten dargestellt. Jede Kamera misst den Einfallswinkel aus einer Ebene, der Schnittpunkt der drei Ebenen definiert den Raumpunkt der strahlenden Leuchtdiode, wie in Fig. 7 dargestellt ist.The three necessary cameras are firmly connected to each other on a stable bar and always have the same, fixed position to each other, to which the system is ultimately calibrated. The entire measuring system can be pre-calibrated by keeping the three cameras in the same position. The given calibration data are automatically loaded into the system each time the program is started. 6 a) and b) the entire measuring system together with three camera units is shown in two variants. Each camera measures the angle of incidence from one plane, the intersection of the three planes defines the spatial point of the radiating light-emitting diode, as shown in FIG. 7.
Die Verwendung von toroidalen, asphärischen Linsen in einem Bewegungsmessgerät ermöglicht den Einsatz von Linearsensoren ohne Qualitätseinbußen. Zur Vermessung von dreidimensionalen Bewegungen werden entweder zwei Flächensensoren oder drei Linearsensoren benötigt. Bereits die einfachsten Linearsensoren lassen sich sehr schnell auslesen, wodurch die Geschwindigkeit des gesamten Messgerätes mit Linearsensoren im Gegensatz zu solchen mit Flächensensoren entsprechend ansteigt. Einfache Linearsensoren weisen bereits eine Pixelzahl von 1.725 auf, sodass sich für die Bewegungsmessung ein Gesamtbild von 1.725 x 1.725 = 2,98 Mio. Bildpunkte ergibt, das in Echtzeit mit einer Samplingrate von 1200 Hz ausgelesen werden kann, wobei die technische Realisierung mittels Linearsensoren einfach ist.The use of toroidal, aspherical lenses in a motion measuring device enables the use of linear sensors without loss of quality. Either two surface sensors or three linear sensors are required to measure three-dimensional movements. Even the simplest linear sensors can be read very quickly, which means that the speed of the entire measuring device with linear sensors increases accordingly, in contrast to those with surface sensors. Simple linear sensors already have a pixel count of 1,725, so that a total image of 1,725 x 1,725 = 2.98 million pixels results for the motion measurement, which can be read out in real time with a sampling rate of 1200 Hz, the technical implementation using linear sensors being simple is.
Desweiteren kann durch den Einsatz von toroidalen, asphärischen Linsen mit einer geringen Linsenanzahl dennoch ein großer Raumwinkelbereich vermessen werden.Furthermore, by using toroidal, aspherical lenses with a small number of lenses, a large solid angle range can still be measured.
Das gesamte Meßsystem hat Öffnungswinkel von +/- 45 Grad und +/- 15 Grad bei einer Systembreite von 1,2 Meter. Das ergibt bei einem Abstand von ca. 3,5 Meter vom System einen Messbereich von 3 x 3 Meter im Raum.The entire measuring system has opening angles of +/- 45 degrees and +/- 15 degrees with a system width of 1.2 meters. This results in a measuring range of 3 x 3 meters in the room at a distance of approx. 3.5 meters from the system.
Durch die Verwendung von Linearsensoren sind die Datenmengen wesentlich geringer als bei Flächensensoren, was den Aufwand der Datenverarbeitung minimiert. Daher kann das echtzeitfähige Meßsystem ohne eigenen Einschubkarte betrieben werden. The use of linear sensors means that the amount of data is much smaller than with area sensors, which minimizes the effort involved in data processing. Therefore, the real-time capable measuring system can be operated without its own plug-in card.

Claims

Patentansprüche: claims:
1. Einrichtung zur Abbildung von Lichtquellen durch mindestens eine optische Linse auf wenigstens einen lichtempfindlichen Sensor, wobei die zur Erzeugung der Abbildung verwendete Optik mindestens eine toroidale Linse aufweist, dadurch gekennzeichnet, dass die Linse(n) neben der toroidalen auch eine asphärische Form aufweist (aufweisen).1. Device for imaging light sources through at least one optical lens on at least one light-sensitive sensor, the optics used to generate the image having at least one toroidal lens, characterized in that the lens (s) has an aspherical shape in addition to the toroidal one ( exhibit).
2. Einrichtung nach Anspruch 1 , dadurch gekennzeichnet, dass mindestens eine Linse aus Kunststoff, vorzugsweise PMMA, gefertigt ist.2. Device according to claim 1, characterized in that at least one lens is made of plastic, preferably PMMA.
3. Einrichtung nach Ansprüchen 1 oder 2, dadurch gekennzeichnet, dass eine im Wesentlichen punktförmige Lichtquelle vorgesehen ist und die Linse(n) diese im Wesentlichen punktförmige Lichtquelle auf eine Linie abbildet (abbilden).3. Device according to claims 1 or 2, characterized in that an essentially punctiform light source is provided and the lens (s) images this substantially punctiform light source on a line.
4. Einrichtung nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass als lichtempfindlicher Sensor ein Flächensensor oder ein Zeilensensor vorgesehen ist.4. Device according to one of claims 1 to 3, characterized in that a surface sensor or a line sensor is provided as the light-sensitive sensor.
5. Einrichtung nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass die Lichtquelle(n) vorzugsweise Infrarotstrahlung aussenden, welches durch die5. Device according to one of claims 1 to 4, characterized in that the light source (s) preferably emit infrared radiation, which by the
Linse(n) auf den Sensor abgebildet wird.Lens (s) is imaged on the sensor.
6. Einrichtung nach Anspruch 5, dadurch gekennzeichnet, dass ein Infrarot-Filter dem lichtempfindlichen Sensor vorgeschaltet ist, um höher- und tieferfrequente Strahlen auszufiltern.6. Device according to claim 5, characterized in that an infrared filter is connected upstream of the light-sensitive sensor in order to filter out higher and lower frequency rays.
7. Einrichtung nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass ein Mehrlinsensystem, vorzugsweise zwei Linsen, eingesetzt werden.7. Device according to one of claims 1 to 6, characterized in that a multi-lens system, preferably two lenses, are used.
8. Einrichtung nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass mindestens drei Linsen-Sensor-Anordnungen verwendet werden.8. Device according to one of claims 1 to 7, characterized in that at least three lens sensor arrangements are used.
9. Einrichtung nach Anspruch 8, dadurch gekennzeichnet, dass die Linsen-Sensor- Anordnungen zueinander eine im Betrieb fixierte Position aufweisen. 9. Device according to claim 8, characterized in that the lens sensor arrangements have a position fixed to one another during operation.
10. Einrichtung nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass die relative Lage von Linse und Sensor einstellbar ist.10. Device according to one of claims 1 to 9, characterized in that the relative position of the lens and sensor is adjustable.
11. Einrichtung nach einem der Ansprüche 1 bis 10, dadurch gekennzeichnet, dass als Lichtquelle eine LED eingesetzt ist.11. Device according to one of claims 1 to 10, characterized in that an LED is used as the light source.
12. Einrichtung nach einem der Ansprüche 1 bis 11, dadurch gekennzeichnet, dass die Außenradien der Linse zwischen 30 mm und 100 mm, vorzugsweise zwischen 45 mm und 65 mm liegen.12. Device according to one of claims 1 to 11, characterized in that the outer radii of the lens are between 30 mm and 100 mm, preferably between 45 mm and 65 mm.
13. Einrichtung nach einem der Ansprüche 1 bis 12, dadurch gekennzeichnet, dass die Innenradien der Linse zwischen 15 mm und 70 mm, vorzugsweise zwischen 30 mm und 50 mm liegen.13. Device according to one of claims 1 to 12, characterized in that the inner radii of the lens are between 15 mm and 70 mm, preferably between 30 mm and 50 mm.
14. Einrichtung nach einem der Ansprüche 1 bis 13, dadurch gekennzeichnet, dass die Linsendicke zwischen 3 mm und 25 mm, vorzugsweise zwischen 7 mm und 15 mm liegt.14. Device according to one of claims 1 to 13, characterized in that the lens thickness is between 3 mm and 25 mm, preferably between 7 mm and 15 mm.
15. Verwendung einer Einrichtung nach einem der Ansprüche 1 bis 14 zur Feststellung von Lage und/oder Bewegung eines Objektes, vorzugsweise in einem Raum, wobei am Objekt mindestens eine Lichtquelle befestigt ist. 15. Use of a device according to one of claims 1 to 14 for determining the position and / or movement of an object, preferably in a room, at least one light source being attached to the object.
PCT/AT2003/000348 2002-11-20 2003-11-20 System for locating light sources WO2004046770A1 (en)

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