Improved light source system with device to provide uniform light

Abstract: An optical system having a light source (10), a uniforming device (61, 31) and an optical fiber type lightguide (50), wherein the uniforming device comprises a first optical transmission portion (31) connected to the lightguide and a second optical transmission portion (61) connected to the first optical transmission portion including a plurality of optical fibers (61A) stretching across the inside thereof which are arranged in such a manner that a light-receiving end (61-1) of each of the optical fibers is placed at a randomly assigned position on a light-receiving end of the second optical transmission portion (61) and on the other hand a light-emitting end (61C) of each of the optical fibers is placed at a randomly assigned position on a light-emitting end of the second optical transmission portion, thereby uniforming the distribution of the quantity of light emitted therefrom.

Description: This invention relates generally to an optical system for transmitting light emitted from a light source to an optical fiber type waveguide or lightguide. More particularly it relates to a light source system including a light source and a device for making uniform the light to be connected to a light-receiving end of an optical fiber type lightguide. A typical optical fiber type lightguide, for example, what is called a "linear pattern outputting lightguide" or a "circular pattern outputting lightguide" (that is, a lightguide having a linear or circular light-emitting end) includes a large number of optical fibers and is adapted to receive and transmit the light received from a light source and output the light from the light-emitting end thereof to an external point. Fig. 16 is a diagrammatical sectional view of a conventional optical system having such a typical lightguide, wherein light radiated from a lamp 11, which can be regarded as a point source of light, is condensed or converged by a reflecting mirror 12. Further, infrared radiation harmful to optical fibers 18 included in a lightguide 15 is removed therefrom by a heat absorbing glass or an infrared absorbing filter 13. Thereafter, the light is directly incident on an end of the lightguide 15. Nowadays, lightguides are widely used for general illumination or lighting. Further, in recent years, lightguides have become employed as light sources of, for instance, inline inspection systems in automated factories, optical business machines and so on. With such spread of lightguides, it has become necessary for the distribution of the quantity of light emitted to be as uniform as possible in every direction of emission of light. Thus, there have been proposed various optical systems provided with a uniforming means 14 such as a diffusing plate 16, a cylindrical or columnar body 17 made of light-transmitting material (hereunder referred to as a cylindrical or columnar light-transmitting device) or the like in a light source system thereof prior to the optical fibers of the lightguide 15 for uniforming, that is, making even the distribution in angle or point of emission (hereunder referred to as "emitting angle") of the quantity of light which is incident on a light-receiving end of the lightguide. A known light source system including a uniforming means for making uniform the quantity of the light, which is incident on the light-receiving end (hereunder referred to as the "incident end") of the lightguide, has the drawback that effects of illumination by the light source are degraded because the quantity of the incident light itself decreases. This is due to the diffusion of the light caused by the diffusion plate, though the uniformity of the distribution entering and leaving the lightguide is promoted with increase of the diffusion coefficient of the diffusion plate. Also, the known light source system employing a columnar or cylindrical light-transmitting device has the defect that it has little effect on the enhancement of the uniformity of the distribution of the quantity of the incident light, though the efficiency of illumination is not decreased. JP-A-62-284313 describes an optical fiber device where beams from a light source are made incident upon a multi-mode optical fiber at an angle from which the beams pass to a relaying optical fiber. This is said to provide a roughly uniform beam intensity distribution at the emitting end of the relaying optical fiber. An optical transmission means comprising a plurality of optical fibers arranged such that an "incident end" of each optical fiber is randomly positioned on the surface of the "incident end" of the optical transmission means and a light-emitting end of each optical fiber is randomly positioned on the surface of the "emitting end" of the optical transmission means is described in JP-A-62-17705. It is an object of the present invention to provide a light source system having an improved light receiving device including a uniforming means which can make more uniform the distribution of the quantity of the light emitted therefrom to the lightguide. In accordance with the present invention, there is provided a light source system comprising:- a device for increasing uniformity of light distribution comprising first optical transmission means for transmitting light from an incident end of the first transmission means to an emitting end thereof; and second optical transmission means which has an incident and an emitting end connected to the incident end of said first optical transmission means, the second optical transmission means including a large number of optical fibres extending between the incident and emitting ends thereof, and arranged such that one end of each of the optical fibres is randomly positioned at the incident end of the second optical transmission means and the other end of each of the optical fibres is randomly positioned at the emitting end thereof; at least one focused light source each positioned such that light from the source is focused by the source on the incident end of said second optical transmission means at a focal position; characterised in that the or each said light source is mounted on position adjustment means that enables displacement of the light source about the incident end of the second optical transmission means thereby to vary the angle ϑ between the optical axis of the or each light source and the axis normal to the incident end of the second optical transmission means to make uniform the distribution of the quantity or intensity of the light emitted from said first optical transmission means. The "incident end" of the second optical transmission means is an open end and arranged in the uniforming device in such a manner to receive the light irradiated by the source of light in various directions. When the light emitted from the source of light is incident on this open end, that is, on the "incident end" of the second optical transmission means, the incident light is transmitted to the "emitting end" thereof by the plurality of optical fibers. An "incident end" of each of the plurality of optical fibers, which are included within the second optical transmission portion, is randomly positioned on the "incident end" of the second optical transmission and on the other hand an "emitting end" of each optical fiber is also randomly placed on the "emitting end" of the second optical transmission means. Thereby, the intensity of the light on the "incident end" of the second optical transmission means is uniformed (that is, the variation in intensity of the light on the "incident end" thereof is decreased or controlled) so that the chiaroscuro, that is, the intensity of the light is uniformly distributed over the "emitting end" thereof. Thus, the light, of which the quantity is uniformly distributed over the "emitting end" of the first optical transmission means, is given to the lightguide. Thereby, the light, of which the distribution of the intensity is substantially uniform over the section of the lightguide, is incident on the "incident end" of the lightguide and as a consequence, the light, of which the distribution of the intensity is substantially uniform over the section thereof, is obtained on the "emitting end" of the lightguide. Moreover, a light source system according to the present invention can transmit the light received from the light source to the lightguide with high efficiency. Thereby, the uniform distribution of the relatively large quantity or intensity of light can be obtained on the "emitting end" of the lightguide. With the light source system of the present invention, the distribution of the quantity of the issued light can be changed by varying the angle ϑ between the optical axis of the light source and the axis normal to the "incident end" of the second optical transmission portion. By adjusting the angle ϑ between the optical axis of the light source and the light receiving device, the distribution of the quantity of the emitted light can be freely changed. BRIEF DESCRIPTION OF THE DRAWINGS Other features, objects and advantages of the present invention will become apparent from the following description of preferred embodiments with reference to the drawings in which like reference characters designate like or corresponding parts throughout several views, and in which: Fig. 1 is a diagram showing a light receiving device for use in an optical fiber type lightguide which has been included to aid understanding of the present invention; Figs. 2, 4 and 6 are diagrams showing different arrangements of devices for measuring the intensity of the light emitted from a test optical fiber uniformed by the light receiving device of the present invention to compare the distribution in "emitting angle" of the quality of the emitted light with that in case of using the prior art light source system; Figs. 3, 5 and 7 are graphs showing the results of the measurements by effected by the systems of Figs. 2, 4 and 6; Fig. 8 shows graphs indicating the variation in the relative quantity of the light, which is incident on the test optical fiber, versus "emitting angles" (that is, angles each formed by a ray of the emitted light and a normal to the "emitting end") thereof in cases of using the light source systems of Figs. 1 and 6; Fig. 9 is a graph showing the relation between a ratio of the length to the diameter of a first optical transmission portion and the variation in quantity of the issued light in cases of using the light source systems of Figs. 1 and 6; Fig. 10 is a diagram showing a light source system embodying the present invention; Fig. 11 is a diagram showing the configuration of devices for rotating the light source of Fig. 10 around a predetermined point; Fig. 12 is a graph showing the relation between the relative quantity of the light emitted from the uniforming means and "emitting angles" thereof and further indicating the variation in quantity of the light emitted from the uniforming means in case that the light source rotates around a predetermined position in accordance with the invention; Fig. 13 is a diagram showing another light source system including two light sources which has been included to aid understanding of a possible application of the present invention; Fig. 14 is a diagram showing an inspection system using the light source system of Figure 1; Fig. 15 is a graph showing variation in the quantity of the light emitted from a linear emitting portion included in the inspection system of Fig. 14; and Fig. 16 is a diagram showing the light source system of a conventional optical fiber type lightguide. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, Fig. 1 is a perspective view of an optical system which employs a light source system connected to an optical fiber type lightguide. A 100 watt halogen lamp 11 provided within a reflecting mirror 12, the inside of which is provided with a dichroic reflecting surface, is used as a source 10, of light. The reflecting mirror 12 and the halogen lamp 11 are arranged such that the light is condensed or converged at a position 24 (hereunder referred to as a "focal position") shown as a circle drawn by a dotted line in this figure. This "focal position" is 40 mm forwardly from a front end 12A of the reflecting mirror 12 along an optical axis thereof. The uniforming device used in the light source system of the present invention is composed of first and second optical transmission portions 31 and 61 connected to each other and arranged such that the "incident end" 61-I of the second optical transmission portion 61 is positioned at the "focal position" 24. In this embodiment, the first optical transmission portion 31 is a columnar or cylindrical light-transmitting device made of acrylic resin and having a diameter of 15 mm and a length of 150 mm. Further, the second optical transmission portion 61 is constructed by fixing both ends of a bundle composed of six hundred plastic optical fibers 61A each having a diameter of 0.5 mm (millimeters) and a length of 1 m (meter) by metal mouth pieces 61B and 61C. A method of fabricating the second optical transmission portion 61 will be further described in detail hereinbelow. First, the bundle composed of the optical fibers 61A is inserted into the mouth piece 61B such that a small portion of an end of the bundle protrudes from the mouth piece 61B. Further, the other end of the bundle composed of the optical fibers 61A is inserted into the mouth piece 61C in such a manner to protrude from the mouth piece 61C. Moreover, an "emitting end" of each of the optical fibers 61A is randomly placed on an outer end surface of the mouth piece 61C and on the other hand an "incident end" of each of the optical fibers 61A is randomly placed on an outer end surface of the mouth piece 61B. This bundle of the optical fibers 61A is fixed at both ends thereof by the mouth pieces 61B and 61C. The mouth pieces 61B and 61C each gripping end of the optical fibers 61A are put into an electric furnace to be given a heat treatment therein. Being treated by the heat of 130 °C for about 10 minutes, both end portions of each of the optical fibers 61A transforms expanding in the radial direction thereof. Thus, the shape of the section of each optical fiber 61A within the mouth pieces 61B and 61C is changed from a circle into a hexagon. Thereby, the density of the optical fibers 61A in the section of the mouth piece 61B or 61C is extremely increased and the optical fibers 61A become fixed within the mouth pieces 61B and 61C. Thereafter, parts of the optical fibers 61A protruding from the mouth pieces 61B and 61C are cut off and further the surfaces of the sections of the optical fibers 61A are abraded and additionally polished to make the surfaces of the ends 61-I and 61-O flat. Thus, the second optical transmission portion 61 is by and large completed. It is, however, preferable that after the above described heat treatment, each of the optical fibers 61A is tentatively pulled out of the mouth pieces 61B and 61C and that epoxy resin is further applied to portions near to the ends of the optical fibers 61A and thereafter the optical fibers 61A are inserted into the mouth pieces 61B and 61C and fixed thereto. As shown in Fig. 1, the second optical transmission portion 61 is straight. Further, the second optical transmission portion 61 is made by bundling up a large number of optical fibers and thus is flexible so that the portion 61 can be easily bent. The thus fabricated second optical transmission portion 61 is a flexible bundle of optical fibers as described above and is a little less than 1 m in length and 15 mm in diameter. This second optical transmission portion 61 is different from ordinary bundles of optical fibers in that an "incident end" of each of the optical fibers 61A is placed at a random, position on the "incident end" of the second optical transmission position 61 and furthermore an "emitting end" of each of the optical fibers 61A is placed at a random position on the "emitting end" of the second optical transmission position 61. The "emitting end" 61-O of the second optical transmission portion 61 is closely connected to an "incident end" of the first optical transmission portion 31. Further, a cylindrical holder (not shown) is used to closely connect the portions 31 and 61 with each other. Moreover, this cylindrical holder is used to put an outer surface of the mouth piece 61C in touch with an outer surface near to an end of the first optical transmission portion 31. In addition, the cylindrical holder is provided with differences in radius of the inner surface thereof in such a manner that the holder fits into both of the outer surface of the mouth piece 61C and that of the first optical transmission portion 31. Furthermore, the first optical transmission portion 31 is closely connected to the "incident end" of the lightguide 50 at the other end thereof. To this end, another holder (not shown) is similarly used. In case where the outer diameter of the first optical transmission portion 31 and that of the lightguide 50 are equal to each other and are 15 mm in case of this embodiment, holders each having no difference in radius of the inner surface thereof are used. If a lightguide whose diameter is less than that of the first optical transmission portion 31 is used, a holder having difference in radius corresponding to the difference in diameter between the first optical transmission portion and the lightguide is used. Next, it will be described hereinbelow as to the capability of the light receiving device of the present invention to make uniform the intensity of the incident light. Figs. 2, 4 and 6 are diagrams for showing the configurations of devices for measuring the extent of uniformity of distribution of the intensity in cases of using no uniforming means, of using only the conventional cylindrical uniforming means and of using the uniforming device of the light source system of Figure 1, respectively. Further, devices equivalent to the light source 10 of Fig. 1 are used as light sources 10 shown in these figures. An end of a plastic optical fiber 23 for use in measurement (hereunder referred to simply as a test fiber), which has a diameter of 0.5 mm and a length of 1 m, is positioned at the center of the focal position of the source 10 of light. Further, a quantity of light issued from the text fiber 23 in this case is set as a unit quantity (that is, 1). Then, distributions in "emitting angle" of the quantity of the issued light are determined in cases that the test fiber 23 is moved in the X- and Y-directions which are perpendicular to both of the optical axis of the source 10 of light and the central axis of the text fiber 23. Moreover, the position of the test fiber 23 first varies from -7 mm to 7 mm in X-direction and then varies from -7 mm to 7 mm in Y-direction. Fig. 3 shows the result of the determination or measurement with no uniforming means, i.e. it shows the distribution of the output of the device 10. Further, in Fig. 3 (and Figs. 5 and 7), a solid curved line indicates the result of the measurement when the test fiber 23 is moved in X-direction and a dotted and curved line indicates the result of the measurement when the test fiber 23 is moved in the direction of Y-direction, the result being a fraction of Pmax, or unity, the intensity at the centre. On the other hand, as shown in Fig. 4, an end of a first acrylic cylindrical light-transmitting device 31 having the same diameter and the same length as those of the first optical transmission portion 31 of Fig. 1, that is, a diameter of 15 mm and a length of 150 mm is placed at the focal position 24 of the light source system as a uniforming means. Furthermore, the test fiber 23 is made close to the other end of the light-transmitting device 31. Then the distribution of the quantity of the emitted light is determined in the manner similar to that described above. Fig. 5 shows the result of this measuring, indicating an improvement. Then, the "incident end" of the second optical transmission portion 61 is additionally arranged as shown in Fig. 6 and further the test fiber 23 is made close to the "emitting end" of the first optical transmission portion 31. Further, the distribution of the quantity of the light issued from the light receiving device is determined. Fig. 7 shows the result of this measurement. As is apparent from comparisons among Figs. 3, 5 and 7, a substantially uniform distribution of the intensity of the emitted light over the whole "emitting end" of the light source system of the present invention can be obtained. Further, the intensity of the light is quantized and the variation in quantity of the emitted light is quantitatively determined as follows. That is, let the maximum and minimum values of the quantity of the light emitted from the test fiber 23 be Pmax and Pmin, respectively. Further, the variation in the quantity of the light issued from the test fiber 23 is defined by ((Pmax - Pmin)/(Pmax + Pmin)) × 100. Thus, variations in quantity of the light issued from the test fiber 23 in the optical systems of Figs. 2, 4 and 6 are listed as below. uniforming means variation in quantity of emitted light (%) not provided (Fig. 2) 69 cylindrical light transmitting device (Fig. 4) 34 uniforming device of the present invention (Fig. 6) 5 As is seen from TABLE 1, in case of the light source system of the present invention as shown in Figs. 6 and 11, the variation in quantity of the emitted light is about a fourteenth the variation in the case of the optical system having no uniforming device as shown in Fig. 2 and is about a seventh the variation in the case of the optical system having only the cylindrical light-transmitting device as shown in Fig. 4. Thus, in comparison with the conventional optical system, the distribution of the quantity of the emitted light is significantly uniformed in the system of the present invention. Fig. 8 shows results of measurement of the quantity of the light 25 emitted from the test fiber 23 of Fig. 6 versus "emitting angles" in cases that the center of the "incident end" of the fiber 23 are placed at the positions represented by (X = 0 Y = 0), (X = +7 mm Y = 0) and (Y = +7 mm X = 0). As is seen from Fig. 8, the angular distribution of the quantity of the issued light is substantially invariant if the center of the "incident end" of the first optical transmission portion 31 is changed. Thus, the diameters of the first and second optical transmission portions 31 and 61 composing the uniforming means of the embodiment of Fig. 1 may be equal to or larger than that of the "incident end" of the lightguide 50 such as the "linear or circular pattern outputting lightguide". Further, the uniformity of the angular distribution of the quantity of the issued light is maintained regardless of the diameters of the optical transmission portions. Fig. 9 is a graph showing change in quantity of the emitted light when the diameter d and the length L of the first optical transmission portion 31, that is, the cylindrical light-transmitting device of Fig. 1 change. As is seen from this graph, if a ratio (L/d) is larger than 2, the variation in the quantity of the issued light is less than or equal to about 9%. Thus, the device of the present invention can be put to practical use. On the other hand, if the ratio (L/d) is exceedingly small, the variation in quantity of the emitted light is drastically increased and becomes about 100% in case that the first optical transmission portion 31 is not used and only the second optical transmission portion 61 is used. This means that light and shade portions on the "emitting end" of the second optical transmission portion 61 can be still distinguished from each other and practically, the second optical transmission portion 61 alone is not enough to obtain the uniform distribution of the quantity of light to be emitted to the lightguide. Fig. 10 is a diagram showing a light source system according to the present invention. This light source system has a light receiving device as the uniforming means as illustrated in Fig. 1, that is, a first and second optical transmission portions 31 and 61. The light source 10 is provided in the system in such a manner to rotate around a "focal position" 24. Consequently, the light source 10 can rotate around the "focal position" 24 on the "incident end" of the second light transmission portion 61 within the range of angle ϑ which is set to be 90° (degrees) in case of this embodiment, around the "focal position" 24 and can be fixed at any angular position within this range of angle. Incidentally, the angle ϑ is defined as an angle formed by an optical axis of the light source 10 and a central axis of the second optical transmission portion 61. Further, Fig. 11 shows a configuration for rotatably providing the light source 10 in the optical system. The light source 10 is fixed to a L-shaped metal fitting 52 which is slidably mounted on a rail 54 and is fixed by a bolt 55 at a certain position such that the "focal position" 24 is on the "incident end" 61-I of the second optical transmission portion 61. Further, this rail 54 is rotatably mounted on a chassis (not shown) by a bolt 56 which is positioned directly below the the "incident end" 61-I of the second optical transmission portion 61. Thus, if the rail 54 rotates around the chassis, the light source 10 rotates around the "focal position" 24. Further, in Fig. 11, reference numeral 58 indicates a heat absorbing glass fixed to the L-shaped metal fitting 52 by another L-shaped metal fitting 59. Thus, the light emitted by the light source 10 is first incident on the transmitted through the heat absorbing glass 58 before incident on the "incident end" 61-I of the second optical transmission portion 61 irrespective of whether any optical waveguide from the light source 10 thereto is provided. Further, the heat absorbing glass or infrared absorbing filter may be also provided in other embodiments as occasion demands. Fig. 12 is a diagram showing the variation in quantity of the light issued from the uniforming means, that is, the second optical transmission portion 61 to the test fiber 23 in cases that the angles ϑ between the optical axis of the light source 10 and an axis perpendicular to the "incident end" 61-I are 0, 20, 25 and 30 degrees, as well as the distribution in "emitting angle" of the quantity of the light emitted from the second optical transmission portion 61 at each of the positions represented by (X = 0 Y = 0). (X = +7 mm Y = 0) and (Y = +7 mm X = 0) in each case that the angle ϑ is 0, 20, 25 or 30 degrees. As is seen from this figure, in case of the light source system of the present invention, the distribution of the quantity of the issued light can be changed by varying the angle ϑ between the optical axis of the light source and the axis normal to the "incident end" 61-I of the second optical transmission portion 61 with maintaining the uniform distribution of the quantity of the emitted light. Namely, by adjusting an angle ϑ between the optical axes of the light source and the light receiving device, the distribution of the quantity of the emitted light can be freely changed. In this embodiment, the range of the angle ϑ is set to be 90° as above stated. It is, however, preferable that this range of the angle is limited to a range from - sin⁻¹(NAmin) - 10° to sin⁻¹(NAmin) + 10° where NAmin is the minimum value of the numerical apertures NA of the lightguides 50 such as a "linear or circular pattern outputting lightguide". Fig. 13 is a diagram showing a light source system which illustrate a possible application for the light source system of the present invention. This light source system has uniforming means as shown in Fig. 1 and further two light sources similar to that of Fig. 1. These sources 10 and 10B are arranged such that the angle formed by segments drawn from the center of the "focal position" 24 on the "incident end" 61-I to these sources is 40 degrees. In case of this embodiment, the quantity of the light emitted from the test fiber 23 is approximately 1.5 times that of the emitted light in case of the single light source in the orientation of Fig. 1. Thus, when the light source system of Fig. 13 requires the same quantity of the emitted light as that of Fig. 1, the halogen lamp 11 of the light source 10 can be used with a voltage applied thereto being decreased. Namely, if two or more light sources are used in the light source system of the present invention, a voltage applied to the light source can be reduced. Thereby, a useful life of the lamp 11 used in the light source system can be significantly longer than a life of the lamp used in the conventional light source system. Fig. 14 is a diagram for illustrating how a light source system is applied to a linear light source in an inline inspection system. The lightguide 50 is composed of a three-decker optical fiber ("ESKA SK 20" manufactured by Mitsubishi Rayon Kabushikikaisha) whose light emitting portion 50B has a diameter of 0.5 mm and a length of 350 mm. In an "incident end" portion (not shown), all of the optical fibers branch into two bundles thereof each having a circular section. Thus, two light sources each of which may be constructed as shown in Fig. 1 are used. Further, an acrylic cylindrical body having a diameter 24mm and a length of 150 mm is used as a first optical transmission portion 31 and a bundle of the optical fibers "ESKA SK20", which has a length of 1 m and a diameter of 24 mm, is used as a second optical transmission portion 61. In the system of Fig. 14, the light emitted from the light emitting portion 50B of the lightguide 50 is irradiated on the surface of an object 70 of inspection such as a paper and the light reflected by the object 70 is detected by a CCD camera 72 which has a one-dimensional array of CCD elements. An output signal of the CCD camera 72 is sent out to a signal analyser 74 whereupon the output signal is processed. The object 70 of inspection is adapted to move at a constant rate as indicated by an arrow and various defects included therein can be detected. Fig. 15 is a graph showing result of measurement of the variation in quantity of the light emitted from the "emitting end" portion 50B of the lightguide 50. To effect this measurement, an object of inspection having a region of uniform reflectivity such as a sheet of white paper is fixed in the system. Further, the light emitted from the lightguide 50 is emitted on the surface of the object of inspection and the reflected light from the object of inspection is received by the CCD camera 72. As a result of the measurement, a good value of the variation in the output of the CCD camera 72 in the whole inspected area, that is, ± 5.3 % is obtained. While the preferred embodiments of the present invention have been described, it is to be understood modifications will be apparent to those skilled in the art.

Claims: A light source system comprising:- a device for increasing uniformity of light distribution comprising first optical transmission means (31) for transmitting light from an incident end of the first transmission means to an emitting end thereof; and second optical transmission means (61) which has an incident and an emitting end connected to the incident end of said first optical transmission means (31), the second optical transmission means including a large number of optical fibres (61A) extending between the incident and emitting ends thereof, and arranged such that one end of each of the optical fibres is randomly positioned at the incident end of the second optical transmission means (61) and the other end of each of the optical fibres is randomly positioned at the emitting end thereof; at least one focused light source (10) each positioned such that light from the source (10) is focused by the source on the incident end of said second optical transmission means (61) at a focal position; characterised in that the or each said light source (10) is mounted on position adjustment means that enables displacement of the light source (10) about the incident end of the second optical transmission means (61) thereby to vary the angle ϑ between the optical axis of the or each light source (10) and the axis normal to the incident end of the second optical transmission means (61) to make uniform the distribution of the quantity or intensity of the light emitted from said first optical transmission means (31). A light source system according to claim 1 wherein the or each position adjustment means is mounted in said light source (10) system so as to enable the respective light source to be rotated about said focal position (24). A light source system according to claim 1 or 2 where said first optical transmission means (31) is for making more uniform the light intensity distribution of the light emitted therefrom. A light source system according to any preceding claim wherein said first optical transmission means (31) is a cylindrical or columnar light-transmitting device made of acrylic resin. A light emitting system including a light source system according to any preceding claim wherein the emitting end of said first optical transmission means is connected to a light guide (50). A light emitting system according to claim 5 wherein the range of the angle ϑ is such that -sin⁻¹(NAmin)-10° ≦ ϑ ≦ sin⁻¹(NAmin)+10° where NAmin is the minimum value of the numerical apertures (NA) of the first and second optical transmission portions (31, 61) and the light guide (50).

Inventors: FUSE MASAKI, ICHIMURA KIYOSHI, SHIBUYA YUKIO, FUSE, MASAKI, ICHIMURA, KIYOSHI, SHIBUYA, YUKIO
Applicants: MITSUBISHI RAYON CO, MITSUBISHI RAYON CO., LTD.
Application year: 1989
Main classification: G02B6
IPC codes: G02B6, F21V8