US3800058A

US3800058A - Light collector for optical organ

Info

Publication number: US3800058A
Application number: US00293738A
Authority: US
Inventors: S Bartok; G Klose; G Stewart
Original assignee: Opsonar Organ Corp
Current assignee: Opsonar Organ Corp
Priority date: 1972-09-29
Filing date: 1972-09-29
Publication date: 1974-03-26
Anticipated expiration: 1991-03-26

Abstract

In an electro-optical organ which includes a device, such as, a rotating disc with numerous concentric tracks of varying opacity representing respective musical tones or sounds and a light source diverting light through all of the tracks, for establishing time-varying light beams representing the musical tones which pass through a relatively long and narrow slit, and a photocell for generating electrical signals in audible to such light beams which signals are employed, for example, in an amplifier and loudspeaker arrangement, for producing corresponding auidble sounds; a light collector is provided for transmitting the light beams from the slit to the photocell and is constituted by a body of light transmitting material having pickup and output ends disposed at the slit and photocell, respectively, and including a first substantially planar portion which tapers from a relatively large width corresponding to the length of the slit at the pickup end to a relatively smaller width at the output end, and second portions directed from the first planar portion at substantial angles to the latter and extending along the first planar to the output end from locations spaced from the output end, with the widths of such second portions increasing progressively therealong toward the output and so as to substantially equalize the cross-sectional areas of the light-transmitting body between its pickup and output ends. The aforementioned second portions may be constituted by longitudinal corrugations in the planar portion of the lighttransmitting body or may extend along the opposite side edges of such planar portion.

Description

United States Patent 1 Bartok et al.

[ LIGHT COLLECTOR FOR OPTICAL ORGAN [75] Inventors:- Stephen Bartok, Gardena; George J.

Klose, Redondo Beach; George W. Stewart, Costa Mesa, all of Calif. [73] Assignee: Opsonar Organ Corporation, Bronx,

[22] Filed: Sept. 29, 1972 [21] Appl. No.: 293,738

[52] US. Cl. 84/1.l8, 250/227, 350/96 R [51} Int. Cl. Gl0h 3/06 [58] Fieldof Search 84/l.l8; 250/227; 350/96 R [5 6] References Cited 1 UNITED STATES PATENTS 3,177,470 4/1965 Galopin 84/l.l8 X 3,411,011 11/1968 Genahr et a1... 250/227 3,752,561 8/1973 Klemt 350/96 R 2,318,144 5/1943 Darke 84/1.l8 2,855,539 10/1958 Hoover .....350/96 R X 2,945,958 7/1960 Morris 84/1.18 X 3,263,070 7/1966 Hine..... 350/96 R X 3,307,020 2/l967 Cahill... 350/96 R X 3,405,222 10/1968 ,Heinzl 84/l.l8 3,484,530 12/1969 Rupert 84/l.l8 3,599,001 8/1971 Rolnik et a1. 250/227 X 3,652,776 3/1972 Milde 84/l.l8 X 3,692,383 9/1972 Herod et al. 350/96 R 3,694,902 10/1972 Apgar et a1. 350/96 R X Primary Examiner-Richard B. Wilkinson Assistant Examiner-Stanley J. Witkowski Attorney, Agent, or FirmAlvin Sinderbrand 51 Mar. 26, 1974 [57] ABSTRACT In an electro-optical organ which includes a device, such as, a rotating disc with numerous concentric tracks of varying opacity representing respective musical tones or sounds and a light source diverting light through all of the tracks, for establishing time-varying light beams representing the musical tones which pass through a relatively long and narrow slit, and a photocell for generating electrical signals in audible to such light beams which signals are employed, for example, in an amplifier and loudspeaker arrangement, for producing corresponding auidble sounds; a light collector is provided for transmitting the light beams from the slit to the photocell-and is constituted by a body of light transmitting material having pickup and output ends disposed at the slit and photocell, respectively, and including a first substantially planar portion which tapers from a relatively large width corresponding to the length of the slit at the pickup end to a relatively smaller width at the output end, and second portions directed from the first planar portion at substantial angles to the latter and extending along the first planar to the output end from locations spaced from the output end, with the widths of such second portions increasing progressively therealong toward the output and so as to substantially equalize the cross-sectional areas of the light-transmitting body between its pickup and output ends. The aforementioned second portions may be constituted by longitudinal corrugations in the planar portion of the light-transmitting body or may extend along the opposite side edges of such planar portion.

7 Claims, 14 Drawing Figures LIGHT COLLECTOR FOR OPTICAL ORGAN BACKGROUND OF THE INVENTION This invention relates to light collectors and especially to light collectors used in optical organs.

One type of optical organ utilizes a rotating disc with numerous concentric tracks; and a lamp that shines light through all of the tracks. A photocell on the side of the tracks opposite the lamp picks up light from any of the tracks and converts the light to electrical signals that are amplified and played through a loudspeaker. A slit is placed between the tracks and photocell to permit light from only a narrow region of each track to reach the photocell. The region near the slit where light from the numerous tracks can be picked up is normally narrow and long. For example, in one organ wherein 7 record tracks are provided which are radially spaced apart by 0.055 inches, the pickup region can be covered by a rectangle which is approximately 3 inches long and less than one-tenth inch thick. All of the light could be picked up by a photocell which was at least 3 inches long. However, photocells of this size are expensive. One type of photocell which can be used is con- .structed from a crystal of silicon. In order to obtain photocells of 3 inches length, crystals would have to be grown which were at least 3 inches in diameter, or at least 6 inches in diameter to utilize most of the crystal material, and such crystals are difficult and expensive to grow. Furthermore, even if such long photocells were available, special care would have to be taken to assure there was no dead spot" along the length of the photocell which did not produce as much current for a given light intensity as was produced by the other regions of the cell. Any such dead spot could result in one of the tracks being played with much less intensity than the other tracks.

OBJECTS AND SUMMARY OF THE INVENTION An object of the present invention is to provide an optical organ which can utilize one or a limited number of relatively small photocells, and wherein the photocells can accurately reproduce recorded sounds even if there are some small localized dead spots in the photocells.

Another object of the invention is to provide a simple and efficient light collector for concentrating light received from a long thin area onto a shorter but thicker area.

In accordance with one embodiment of the present invention, an optical organ is provided which utilizes a photocell of small dimensions to receive time-varying light patterns that are originally arranged along a pickup region that is much wider than any dimension of thephotocell. The organ utilizes a light collector with a pickup end that substantially covers the pickup region where light patterns are received from an optical record, and an output end where the light is delivered to the photocell. The light collector also has an intermediate portion containing surfaces for internally refleeting light along predetermined paths, from each area of the pickup region where light from one optical track is received to the output end. The intermediate portion is formed so that at least some to the light paths include a predetermined limited number of internal reflections.

In one type of light collector, the light collector has a main sheet or planar portion extending from the pickup end to the output end and is tapered in width along at least some of its length so that it is progressively narrower nearer the output end. At least two auxiliary sheets or portions intersect the main sheet, and each auxiliary sheet is progressively wider at locations nearer the output end. The auxiliary sheets or portions may be constituted by corrugations extending longitudinally in the main sheet or planar portion, or may extend along the opposite side edges of the main sheet.

In another light collector, a main sheet is provided which is tapered in width so that its edges reflect light to a central portion of the sheet. The central portion has a recess with numerous inclined walls that reflect light out of the plane of the sheet.

The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention will best be understood from the following description when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial, simplified perspective view of an optical organ including a light collector of the invention; I

FIG. 1A is a sectional view taken on the line 1A1A of FIG. I;

FIG. 2 is a partial, perspective view of an organ with a light collector constructed in accordance with a second embodiment of the invention;

FIG. 3 is a perspective view of a light collector constructed in accordance with a third embodiment of the invention;

FIG. 4 is a side elevation view of of FIG. 3;

FIG. 5 is a view taken on line 55 of FIG. 4;

FIG. 5A is a view taken on the line 5A-5A of FIG.

the light collector FIG. 6 is a view taken on the line 66 of FIG. 4;

FIG. 7 is an enlarged side elevation view of the region 7-7 of FIG. 4;

FIG. 8 is a perspective view of a light collector constructed in accordance with a fourth embodiment of the invention, the light collector being similar to that of FIG. 3 except that it includes numerous slits at its pickup end that form light collecting fingers;

FIG. 9 is a perspective view of a light collector constructed in accordance with a fifth embodiment of the invention;

FIG. 10 is a side elevation view of the light collector of FIG. 9;

FIG. 11 is a partial rear elevation view taken on the line l1ll of FIG. 10; and

FIG. 12 is a sectional view taken on the line 12-12 of FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS opposite the lamp. The mask blocks the passage of light except at a narrow, long slit formed in the mask. Light from the record that passes through the slit 20 can be made to reach a photocell 22 that converts the light to electrical signals. The electrical signals pass through an amplifier 23 and drive a loudspeaker 25.

Light from the region of the slit 20 is carried to the photocell 22 by a light collector 24. The light collector 24 has a pickup end 26 which can substantially cover and therefore pick up light form the slit 20, and an output end 28 where the light which is picked up is delivered to the photocell. The organ must be constructed so that light from any of the tracks 12 that passes through the mask 20 does not reach the photocell until a selected key 30 of a keyboard 32 is depressed by a musician. To provide for this, the pickup end portion 26 of the light collector is provided with numerous long slits that form individual light collecting fingers 34. The light collector 24 is formed of a transparent resilient material, such as an acrylic plastic and the light fingers 34 normally assume a position wherein their tips lie a distance to the side of the slit 20. When any one of the light fingers, such as the light finger 34a, is deflected over the slit 20, the light finger picks up light from one of the tracks 12 and permits light from that track to pass to the photocell 22. Each key 30 is connected by a pivotally mounted crank 36 and a long rod 38 to a corresponding light finger 34, so that when a key 30 is depressed, the rod 38 slides and deflects a corresponding light finger over the slit. g

The pickup region, which is the area immediately over the slit 20 where light can be picked up, is wide and thin. The initial portion 40 of the light collector that lies immediately past the inner ends of the fingers 34 is also wide and thin. However, the light collector also has an intermediate portion 42 which collects light from the wide thin portion 40 and directs it onto the output end 28 of the light collector. The output end 28 has a width W, which is much less than the width W Of the initial portion 40. This permits a photocell 22 to be used which has only a small width W It would be possible to utilize a light collector without the middle portion 42 and output end 28, so that the light collector would end at the initial portion 40 which is wide and thin. However, the photocell for picking up light would then have to have a width W equal to that at the pickup end 26 of the light collector. This can lead to considerable expense, inasmuch as photocells suitable for an organ and which have a length of substantially more than one inch are expensive. One series of records 10 has 57 record tracks spaced 0.055 inches from one another, so that a pickup region of 3 inches in width is required to pick up light from all tracks. In some organs, two photocells are utilized, one picking up a group of twenty tracks representing chords or other accompaniment patterns of notes, and the other picking up 37 tracks representing sustained notes. However, the 37 track group has a length of about 2 inches, and a photocell of even 2 inches in length is expensive. Such a photocell is not required because the light collector 24 can concentrate light to a more compact area that can be covered by an inexpensive photocell. Photocells of a standard size such as 1 cm. by 2cm. are available at low cost, and the output end 28 of the light collector can be formed so it can be covered by a photocell of this size.

An important advantage of the light collector 24 is that it distributes the light from any light finger 34 over a large area of the output end 28. The tip of each finger 34 can cover a small pickup area where it can receive light from one optical track. If all of this light were incident on a small area of a photocell, then it would be necessary that all regions of the photocell be equally sensitive to light. If the photocell had a dead area" that had a low sensitivity, and if all of the light from a light finger were incident only on that dead area, then only a very low level of sound could be obtained from the corresponding optical track. The light collector 24, however, distributes the light picked up at a small pickup area, so that although some of the light from any pickup area may fall on a dead area of a photocell, most of the light from any pickup area will be distributed over other photocell areas which are more sensitive. Accordingly, any diminution of output due to the dead area of the photocell will be very small and generally unnoticable.

The intermediate portion 42 of the light collector is tapered in width W, as measured between its opposite sides, so that the light collector is of progressively smaller width at.locations progressively closer to the output end 28. In addition, the middle portion 42 of the light collector has folds or corrugations formed therein along its length, so that the corrugations appear in a cross section taken along the width of the light collector as in FIG. IA. The corrugations progressively increase in height H at locations progressively closer to the output end 28 of the light collector. Accordingly, although the width of the light collector progressively decreases, the cross-sectional area of the light collector does not change much, if at all, between the pickup end 26 or initial portion 40 and the output end 28.

The exact dimensions of each portion of the light collector 24 must be chosen so that approximately the same proportion of light reaching each pickup area, or each light finger 34, reaches the output end 28. The design of a light collector can be a difficult problem. In the light collector of FIGS. I and 1A, most of the light or light beams reaching the initial area 40 undergo one or more reflections prior to reaching the output end 28. The light collector 24 is designed -so that the light beams from any region of the initial portion 40 travel along predetermined paths. At least some of these paths include a predetermined limited number of internal reflections prior to the light beams reaching the output end 28. This construction may be contrasted with the use of a cylindrical rod or other simple piece of transparent material wherein light hitting the sides of the rod can be picked up at either end of the rod by reason of diffusion of light due to irregularities in the surface of the rod which result in diffusion of the light in all directions. In the case of such a rod, the number of internal reflections of light is not limited and the proportion of light reaching either end from any pickup area of the pickup region is unknown and generally grossly unequalto the proportion from some other pickup areas. The analysis of a light collector can be extremely complex where the internally reflecting surfaces are compoundly curved, that is, where locations on the surface are simultaneously curved about more than one axis. In order to permit rigorous analysis of a light collector, to assure that approximately the same proportion of light incident on any of the numerous pickup areas reaches the output end, the light collector should contain primarily planar surfaces.

FIG. 2 illustrates an organ constructed in accordance with another embodiment of the invention which utilizes a light collector 50 containing substantially only planar surfaces. The light collector therefore can be rigorously analyzed and designed to assure that approximately the same high proportion of light beams from all pickup areas reach the photocell. The organ of FIG. 2 utilizes a row of pivotally mounted light shutters 52 which have light blocking portions 54 that normally block the passage of light that emanates from the record and passes through the slit 20. However, when one of the rods 38a is pushed, it pivots one of the shutters 52a so that light can reach a pickup area at the pickup region 56 of the light collector. Light received at the pickup region 56 passes along a middle region 58 to an output end 60 of the light collector. A photocell indicated at 62 is positioned directly over (and normally against) the output end 60 to pick up the light.

The middle region 58 of-the light collector 50 includes a sheet or planar portion 64 which is tapered in width so it is of progressively narrower width at locations progressively closer to the output end 60. The sheet 64 is also corrugated, having four

corrugations

66, 67, 68 and 69 which are of progressively greater height at locations progressively closer to the output end. Thus, although the overall width of the light collector decreases towards the output end, the crosssectional area of the light collector undergoes a smaller rate of decrease in area, if any, as locations pr0gres vsively closer to the output end. The middle portion 58 of the light collector can also be described as including a main sheet 64 with slots 70, 71, 72 and 73 therein, and as including auxiliary sheet portions formed by each side of the corrugations 66-69 which intersect the main sheet 64 at the edges of themain sheet, and with the planes'of the auxiliary sheet portions extending perpendicular or at substantial angles to the plane of the main sheet 64. Each of the auxiliary sheets is tapered in width so that itis progressively wider at locations progressively nearer the output end 60 of the light collector. In addition, the pairs of auxiliary sheets formed by the corrugations 66-69 are thicker than the main sheet 64.

FIGS. 3-7 illustrate a light collector 80 constructed in accordance with still another embodiment of the invention, this light collector being relatively small and economical to mold and yet being highly efficient. The light collector 80 includes a pickup end 82 which can lie over a region where light is received, an output end 84 which can carry a small photocell, and a middle portion 86 which collects light so that approximately the same proportion of light from individual small pickup areas at the pickup end 82 reach the output end 84. The light collector includes a main sheet portion 87 which extends between the pickup and output ends, which is of uniform width along a portion near the pickup end 82, and which is tapered in width along the middle portion 86 of the light collector. The light collector also includes a pair of

auxiliary sheets

88, 90, which intersect the opposite edges of the main sheet 80 along the tapered portion of th'einain sheetfand provide the light collector with a corrugated cross-section. The

auxiliary sheets

88, 90 are tapered in width, increasing in width from a substantially zero width at one end 92 where the main sheet begins to taper to a maxi mum width at the output end 84 where the main sheet is of minimum width. As illustrated in FIG. 5A, each auxiliary sheet such as sheet 90 intersects the main sheet 87 primarily perpendicular to the plane of the main sheet, that is, at more than 45, the actual angle B being about The light collector also has a sheetlike portion at the output end 84, which functions only to brace the auxiliary sheets. Three

bracket portions

94, 96, and 98 project from selected parts of the main sheet to provide mounting brackets for supporting the light collector on an organ frame.

The light collector is constructed in accordance with a rigorous analysis of light beams receivable at any pickup area of the pickup end 82, and receivable within predetermined solid angles, to assure that approximately the same proportion of light from any of the pickup areas reaches a photocell at the output end 84. Among the details of construction, it may be noted that the

edges

100, 102, where the auxiliary sheets 88, intersect the main sheet 80, are beveled on the outside, so the outer corner surface is angled from the faces of both the main sheet 80 and the adjacent

auxiliary sheet

88 or 90. The beveling is provided to assure that light beams passing within the main sheet and striking an edge of the main sheet will be internally reflected into the auxiliary sheet. The paths of two

light rays

101 and 103 are illustrated, the path of ray 101 including reflections at the beveled edge 102 and at the opposite edge of auxiliary sheet 90, and the path of ray 103 including a reflection at the beveled edge 102. The light collector is constructed of a material, such as an acrylic plastic which has an index of refraction of approximately 1.5. Accordingly, a total internal reflection will occur at an angle of incidence of more than about 42. It has been found that the

auxiliary sheets

88, 90 generally must be thicker than the main sheet 87 from which they receive light in order to insure capture of a high proportion of light from the main sheet.

The light collectors are most economically produced by molding, especially by injection molding, and the speed of production can be increased by utilizing thin sheet surfaces. The thickest portions of the light collector are generally at the

auxiliary sheets

88, 90 which generally must be thicker than the main sheet 87. The

thickness of the auxiliary sheets is minimized by making the main sheet 87 especially thin. While a thin main sheet 87 can efficiently transmit light, it sometimes may not be efficient in picking up light at its pickup end. The ability of the light collector to pick up light is increased by enlarging the pickup end portion 82 so that it can pick up light over a thicker area or wider angle. The use of an increased thickness at the pickup end 82 of the main sheet, in a main sheet 87 that is thin along most of its area, plus the thicker auxiliary sheets, results in efficient light pickup and collection in a light collector that can be injection molded at a rapid rate, and which therefore can be produced economically. It may be noted that the light collector has a central bulging portion or rib 104 extending along the length of the middle portion 86. The rib 104 is provided to dissipate a higher proportion of light received near the center of the pickup region 82, to more nearly equalize the proportion of light from all of the pickup areas that reach the output end 84.

FIG. 7 illustrates details of the thickened tip or pickup end portion 82 of the light collector. The light collector is of uniform shape all along the width of the pickup end 82. The thick pickup end has a pair of

facets

106, 108 that make the tip convex instead of merely flat. The convex end helps to direct light received over a considerable angle A from the slit 20 in the mask 18, so that light within the angle will pass along the light collector and reach the output end. By enabling the pickup of light over a considerable angle A, such as 30, a larger proportion of available light is picked up, so that a larger and therefore less noisy signal is obtained from the photocell.

FIG. 8 illustrates a light collector constructed in accordance with another embodiment of the invention, wherein the light collector 120 is substantially identical to the light collector 80 of FIG. 3, except that its pickup end portion 82 has numerous slits which divide the end into light collecting fingers 122. The light collecting fingers 122 operate in the manner indicated for the fingers 34 of the light collector of FIG. 1, each of the fingers being normally lying in a position wherein they cannot pick up light from an optical track.

FIGS. 9-12 illustrate a light collector 130 constructed in accordance with yet another embodiment of the invention. The light collector 130 includes a sheet portion or sheet 132 which has a pickup end 134 and which is tapered between the pickup end 134 and another, opposite end 136, to form a substantially parabolic edge. However, the output region 138 where a photocell 140 can be located, is not at the second end 136 where the sheet is of minimum width. Instead, the output region is located at a middle or deflector portion 142 of the sheet. The deflector portion 142 is thickened and has a recess 144. The recess 144 has inclined walls such as

walls

146, 148 best illustrated in FIG. 12, which reflect light out of the plane of the sheet 132.

The tapered portion of the sheet 132 has an edge 150 of substantially parabolic shape, as viewed in a front elevation view, for internally reflecting light beams that enter the pickup end 34 so they are received at the deflector portion 142. The beveled walls 146 of the recess 1 from pickup areas near the middle of the pickup end 134. In addition, a pair of mounting bosses 154 are provided which facilitate mounting of the light collector.

Thus, the invention provides an optical organ which can utilize a limited number of relatively inexpensive photocells, even though the light patterns to be picked up extend along a wide pickup region. The organ utilizes a light collector which concentrates the light from a wide thin region to a less wide but thicker region that can be covered by a relatively inexpensive photocell. The light collector carries approximately the same proportion of light from each pickup area, where light from each optical track is received, to the photocell. The light collector has a pickup end where it receives light, an output end where it' delivers light to a photocell, and an intermediate portion which carries light along predetermined paths from each pickup area to the output end, at least some of the paths includinga limited number of internal reflections. In some light collectors, some of the rays are reflected at only one or two edge regions of the sheet-like portions. The light collector can be constructed with a main sheet of transparent material with a portion that is tapered in width so it is progressively narrower in width at locations progressively further from the input end. In one type of collector, a plurality of auxiliary sheets are provided which are of progressively greater width at locations progressively further from the input end of the light collector. In another type of light collector, the main sheet has a central portion with a recess that has inclined walls for reflecting light largely perpendicular to the sheet. While the light collector is preferably uncoated to minimize costs, it is possible to apply aluminum or other reflective coatings to selected surfaces.

Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art and consequently it is intended that the claims be interpreted to cover such modifications and equivalents.

What is claimed is:

1. An optical organ comprising:

a light collector constituted by a body of lighttransmitting material having spaced apart pickup and output ends and including a first substantially planar portion which tapers in width from a relatively large width at said pickup end to a relatively smaller width at said output end, and second portions directed at substantial angles from said first planar portion and extending along the latter to said output end from locations spaced from said output end, the widths of said second portions increasing progressively therealong in the directions toward said output and so as to substantially equalize the cross-sectional areas of said body at said pickup and output ends;

means for establishing time-varying light beams representing sounds and which are selectively directed into said first planar portion of the lighttransmitting body at respective spaced locations across said pickup end;

photosensitive means positioned at said output end of the light-transmitting body for generating electrical signals in response to light beams transmitted through said body; and

means responsive to said electrical signals for generating corresponding sounds.

2. An optical organ according to claim 1; in which said second portions of the light-transmitting body have greater thicknesses than said first planar portion.

3. An optical organ according to claim 1; in which said first planar portion has corrugations extending longitudinally therein with the flanks of said corrugations increasing in depth to said output end for defining said second portions.

4. An optical organ according to claim 1; in which said first planar portion has opposite side edges which converge in the directiontoward said output end, and said second portions extend along said side edges of said first planar portion.

5. An optical organ according to claim 4; in which said side edges along which the second portions extend are bevelled.

6. An optical organ according to claim 1; in which the edge of said first planar portion at said pickup end of the light-transmitting body is relatively thicker than the remainder of said first planar portion and is convex.

7. An optical organ according to claim 1; in which said first planar portion has light-dissipating means centrally located therein for minimizing the proportion of the light reaching said output end from the central part of said pickup end.

Claims

1. An optical organ comprising: a light collector constituted by a body of light-transmitting material having spaced apart pickup and output ends and including a first substantially planar portion which tapers in width from a relatively large width at said pickup end to a relatively smaller width at said output end, and second portions directed at substantial angles from said first planar portion and extending along the latter to said output end from locations spaced from said output end, the widths of said second portions increasing progressively therealong in the directions toward said output and so as to substantially equalize the cross-sectional areas of said body at said pickup and output ends; means for establishing time-varying light beams representing sounds and which are selectively directed into said first planar portion of the light-transmitting body at respective spaced locations across said pickup end; photosensitive means positioned at said output end of the lighttransmitting body for generating electrical signals in response to light beams transmitted through said body; and means responsive to said electrical signals for generating corresponding sounds.

4. An optical organ according to claim 1; in which said first planar portion has opposite side edges which converge in the direction toward said output end, and said second portions extend along said side edges of said first planar portion.