TWI725372B - Endoscope light source module - Google Patents

Abstract

The present invention is an endoscope light source module. A light splitting device reflects the first light of the first light source, the detection light of the detection light source, and the white light that transmits the white light source to form a mixed light for the light processing element to receive and project. In this way, the high color rendering and special optical characteristics of the mixed light are used to enhance the application range and utility of the present invention.

Description

Endoscope light source module

The present invention relates to a light source module, in particular to an endoscope light source module combining high color rendering and ultraviolet optical characteristics.

The lighting device used in the endoscope equipment, hereby transmits a plurality of light sources of different colors combined with a lens/dichroic mirror to form white light, a single/plural light source combined with phosphor excited light, and then matches a lens/dichroic mirror to produce white light, or It is a combination of multiple light sources and the light excited by the phosphor, which is mixed with a lens/dichroic mirror to form white light, etc., for use in endoscope equipment.

Patent numbers such as US8803056B2, US9459415B2, and China CN102499615A all disclose the technology of using a lens/dichroic mirror to combine the light sources of the three primary colors of red, green and blue to form white light. For example, the patent number of China CN108459409A is a technology that generates white light for output by combining a light source with a phosphor through the action of a dichroic mirror. For example, the patent number of US20160022126A1 discloses that the light source includes white light composed of red, green, and blue light sources in the first mode, and mixed light composed of infrared light, blue light source, and green light source in the second mode. The two operating modes are based on The medical team provides appropriate light to interpret the symptoms during the diagnosis process.

The color rendering performance of white light generated by the above-disclosed conventional technology is generally poor, and cannot fully present the true appearance of the subject. In addition, as far as the equipment used in endoscopes is concerned, due to the inspection of the patient’s symptoms (such as the tissues, cells, blood, etc.) of the patient during the operation, it is impossible for medical personnel to accurately determine whether it is irradiated with white light. It belongs to related symptoms, that is, the manifestation of symptoms requires special light sources to effectively bring out pathological information for medical personnel to diagnose. Therefore, in addition to the problem of color rendering that needs to be improved, if the lighting considerations are based on special needs, there are also unsatisfactory areas that need to be improved. Therefore, there is a need to improve the technical means of generating white light and applying it to lighting in accordance with the above-mentioned conventional methods.

One object of the present invention is to provide an endoscope light source module, which combines the white light generated by the white light source with the red light of the first light source and the detection light of the detection light source to form a mixed white light through a beam splitting device, thereby enhancing the traditional white light It has color rendering and special optical characteristics to improve the efficiency of medical diagnostic applications of endoscopy.

One objective of the present invention is to provide an endoscope light source module, which receives mixed white light through a light processing element, and according to the tapered structure of the light-receiving part toward the light-emitting part, the irradiation range of the mixed white light projected by the light-emitting part is increased, and the visibility is improved. area.

In order to achieve the aforementioned purposes and effects, the present invention discloses an endoscope light source module, which includes: a white light source, including a white light beam; a light source device, including a first light source and a detection light source, first The light source includes a first light, the detection light source includes a detection light, and the first light source and the detection light source are arranged opposite to each other; a beam splitting device is arranged between the first light source and the detection light source to reflect the first light and the second light to make white light The light transmission beam splitting device is mixed with the first light and the second beam to form a mixed light; a light processing element is arranged on one side of the beam splitting device and receives the mixed light.

In order to enable your reviewer to have a better understanding and understanding of the features of the present invention and the effects achieved, only the description of the examples and the accompanying illustrations are provided, and the description is as follows:

Please refer to the first figure, which is a schematic diagram of the first embodiment of the present invention. As shown in the figure, the present invention includes an endoscope light source module 1, which includes a white light source 10, which includes a white light ray 100; a light source device 12, which includes a first light source 120 and a detection light source 122, The first light source 120 is arranged opposite to the detecting light source 122, the first light source 120 includes a first light 1200, the detecting light source 122 includes a detecting light 1220, and the white light ray 100 intersects the projection directions of the first light 1200 and the detecting light 1220; a split light The device 14 includes a first beam splitter 140 and a second beam splitter 142. The first beam splitter 140 is arranged on one side of the first light source 120 to reflect the first light 1200, and the second beam splitter 142 is arranged on the detecting light source 122. One side reflects the detection light 1220. The white light source 10 is arranged on one side of the first beam splitter 140 and the second beam splitter 142. The white light beam 100 transmits through the beam splitter 14 and is mixed with the reflection of the first light 1200 and the reflection of the detection light 1220 A mixed light L is formed; a light processing element 16 is arranged on the other side of the first beam splitter 140 and the second beam splitter 142, including a light receiving part 160 and a light emitting part 162, one side of the light receiving part 160 is opposite The light L is mixed, and the other side is extended and connected to the light emitting portion 162, and is arranged to be tapered from the light receiving portion 160 to the light emitting portion 162.

Please also refer to the second figure, which is a schematic diagram of the light splitting device according to the first embodiment of the present invention. As shown in the figure, the first beam splitter 140 of the beam splitter 14 includes a first surface 1400 and a second surface 1402, and the second beam splitter 142 includes a third surface 1420 and a fourth surface 1422, and the first light 1200 is projected The first beam splitter 140 is reflected by the first surface 1400 to mix with the white light 100 and move toward the light processing element 16. The detection light 1220 is projected on the second beam splitter 142, is reflected by the third surface 1420, is mixed with the white light 100, and moves toward the light processing element 16.

The first dichroic mirror 140 and the second dichroic mirror 142 are arranged to intersect each other perpendicularly and form an X shape. In other words, the intersection of the first surface 1400 and the third surface 1420 forms a first angle θ1, the intersection of the first surface 1400 and the fourth surface 1422 form a second angle θ2, and the intersection of the second surface 1402 and the third surface 1420 form a third angle. The included angle θ3, the intersection of the second surface 1402 and the fourth surface 1422 forms a fourth included angle θ4. The first, second, third, and fourth included angles θ1, θ2, θ3, θ4 are 90 degree angles. The arrangement of the first beam splitter 140 and the second beam splitter 142 is not only the option of perpendicularly intersecting X-shaped, but is set according to the light path matching of the first light 1200, the detection light 1220 and the white light 100, not according to the present invention. The listed embodiments are limited.

Please refer to the third figure, which is a schematic diagram of the white light source according to the first embodiment of the present invention. As shown in the figure, the white light source 10 includes: a second light source 102, which includes a second light 1020; a third light source 104, which includes a third light 1040, and the second light source 102 and the third light source 104 are arranged opposite to each other; The third beam splitter 106 includes a fifth surface 1060 and a sixth surface 1062. The fifth surface 1060 and the sixth surface 1062 are disposed opposite to each other. The fifth surface 1060 is disposed on one side of the second light source 102 to reflect the second light 1020. , The sixth surface 1062 is arranged on one side of the third light source 104 to reflect the third light 1040; a reflecting device 108 is arranged on one side of the fifth surface 1060 to receive the second light 1020 reflected by the fifth surface 1060, and A reflected light 1080 is formed to transmit through the third beam splitter 106, and the reflected light 1080 and the third light 1040 are mixed to form a white light beam 100 and transmitted through the beam splitting device 14.

The reflecting device 108 includes a reflecting mirror 1082, a fluorescent body 1084 and a collecting lens 1086. The fluorescent body 1084 is arranged on one side of the reflecting mirror 1082, and receives the second light 1020 reflected by the fifth surface 1060, and is self-reflecting The mirror 1082 generates the reflected light 1080, and then transmits the third beam splitter 106 to mix with the third light 1040 to form a white light light 100. The condensing lens 1086 is arranged on one side of the reflecting mirror 1082 and the phosphor 1084 to cover the phosphor 1084 and concentrate the second light 1020 reflected by the fifth surface 1060 on the phosphor 1084.

The first light source 120 is at least one red laser beam or a red light-emitting diode, and the first light 1200 is light with a wavelength of red (620-750 nm). The detection light source 122 is at least one ultraviolet laser beam or ultraviolet light emitting diode, and the detection light 1220 is light with a wavelength belonging to ultraviolet light (above 395 nm), such as 395 nm, 400 nm, 405 nm, and other wavelength bands. The second light source 102 and the third light source 104 are at least one blue laser beam or a blue light-emitting diode, and the second light 1020 and the third light 1040 are light whose wavelength belongs to blue (450-475 nm). The reflected light 1080 is light whose wavelength belongs to yellow (570-590nm). The mixed light L is light whose wavelength belongs to white and ultraviolet light. The phosphor 1084 is yellow phosphor. In addition, the first light source 120, the detection light source 122, the second light source 102, and the third light source 104 are set according to the illumination requirements, and a plurality of laser beams/light emitting diodes can be arranged in an array, or only a single laser beam can be set /Light-emitting diodes are not limited to this.

The first beam splitter 140, the second beam splitter 142, and the third beam splitter 106 are each designed to allow light of a specific wavelength to pass through directly, and to reflect light of another specific wavelength to be projected or transmitted to other components. The first beam splitter 140 reflects red light (the first light 1200), and allows ultraviolet light (detection light 1220) and white light (white light 100) to pass, and the second beam splitter 142 reflects the ultraviolet light (detection light 1220), and allows the red light to pass through. Light (first light 1200) and white light (white light 100) pass through, and the third beam splitter 106 reflects blue light (second light 1020, third light 1040) and allows yellow light (reflected light 1080) to pass.

Referring again to the third figure, the operation mode of the first embodiment of the present invention will be explained continuously. First, the second light source 102 uses a six-by-four array of blue laser beams (Blue laser array) arranged on one side of the third beam splitter 106 as a main light source, and projects the second light 1020 to the third light beam with blue light. The mirror 106 is in contact with the fifth surface 1060. Since the optical characteristic of the third beam splitter 106 is to reflect blue light and allow yellow light to pass through, the fifth surface 1060 reflects the second light 1020 and moves toward the reflecting device 108 (as shown in the third figure, it moves to the left). When the second light 1020 reflected by the fifth surface 1060 travels to the reflecting device 108, the collecting lens 1086 acts as a convex lens to concentrate the second light 1020 on the phosphor 1084, and the phosphor 1084 is coated with yellow phosphor powder On the reflector 1082, it can be excited by the second light 1020 to generate yellow light. In detail, most of the second light 1020 illuminates the phosphor 1084 through the collecting lens 1086, and the generated yellow light is reflected by the reflector 1082, and part of the second light 1020 directly irradiates the reflector 1082, and is reflected by the reflector 1082. It is excited again with the phosphor 1084 to generate yellow light. Here, all the yellow light excited by the contact of the second light 1020 with the phosphor 1084 is reflected by the reflector 1082 to generate the reflected light 1080, and then moves to the third beam splitter 106 (as shown in the third figure, the belt The light with yellow light moves to the right).

On the other hand, the third light source 104 uses a single blue light-emitting diode arranged on the other side of the third beam splitter 106 as another main light source, and projects a third light ray 1040 with blue light to the third beam splitter 106 and The sixth surface 1062 is in contact. Since the optical characteristics of the sixth surface 1062 are the same as those of the fifth surface 1060 (both reflect blue light and transmit yellow light), the sixth surface 1062 will reflect the third light 1040 toward the beam splitting device 14 (as shown in the third figure, as the direction Move right). The light moving in the direction of the beam splitting device 14 has the third light (blue light) 1040 reflected by the sixth surface 1062, and the reflected light (yellow light) 1080 directly transmitted through the third beam splitter 106, and these light rays pass through the third beam splitter. The mirror 106 is combined into a white light (white light) 100, which is the process in which the white light source 10 generates the white light 100.

Referring to the first and second figures again, the manner in which the spectroscopic device 14, the first light source 120, the detection light source 122 and the white light ray 100 operate will be described here. The optical characteristic of the first beam splitter 140 is to reflect red light and allow ultraviolet light and white light to pass through. The optical characteristic of the second beam splitter 142 is to reflect ultraviolet light and allow red light and white light to pass through. Therefore, at the beginning, the white light 100 generated by the white light source 10 directly transmits the first beam splitter 140 and the second beam splitter 142 of the beam splitting device 14. The first light source 120 is arranged on one side of the first beam splitter 140 with a single red light-emitting diode, and projects a first light 1200 with red light until the first beam splitter 140 contacts the first surface 1400. During the projection process, part of the first light 1200 first contacts the first surface 1400, is reflected by the first surface 1400, and then transmits through the third surface 1420 and the fourth surface 1422 of the second beam splitter 142, and finally moves to the light processing element 16. The other part of the first light 1200 first transmits the third surface 1420 and the fourth surface 1422 of the second beam splitter 142, and then is reflected by the first surface 1400, and finally moves to the light processing element 16 (as shown in the first figure, To move to the right).

In the same way, the detection light source 122 is a single ultraviolet light-emitting diode arranged on one side of the second beam splitter 142, and the detection light 1220 with ultraviolet light is projected to the second beam splitter 142 to contact the third surface 1420. During the projection process, part of the detection light 1220 first contacts the third surface 1420, is reflected by the third surface 1420 and then transmits through the first surface 1400 and the second surface 1402 of the first beam splitter 140, and finally moves to the light processing element 16. The other part of the detection light 1220 first transmits the first surface 1400 and the second surface 1402 of the first beam splitter 140, and then is reflected by the third surface 1420, and finally moves to the light processing element 16 (as shown in the first figure, move to the right). The light moving in the direction of the light processing element 16 has the first light (red light) 1200 reflected by the first surface 1400, the detection light (ultraviolet light) 1220 reflected by the third surface 1420, and directly transmits the first beam splitter 140. The white light (white light) 100 of the second beam splitter 142 is combined into a mixed light (white light) L by the light splitting device 14, which is the process of generating the mixed light L.

Thereafter, the light receiving part 160 of the light processing element 16 receives the mixed light L, and then projects the mixed light L on the light emitting part 162. The light processing element 16 is an optical fiber with a diameter of 3 mm. Through the tapered structure (or tapered structure) of the light processing element 16, the range of the mixed light L projected from the light emitting portion 162 can reach an irradiation range of 30 degrees or more. In addition, the mixed light L solves the problem of poor color rendering of the traditional white light, that is, the white light 100 is mixed with the first light 1200 to improve the color rendering of the overall white light. In addition, the white light 100 is mixed with the detection light 1220, so that the mixed light L has the special optical characteristics of ultraviolet light generation. As the lighting element of the endoscope equipment, the present invention can improve the medical personnel to provide a real human body structure appearance during the diagnosis of irradiated symptoms due to the high color rendering property of the mixed light L, and prevent the medical personnel from misjudgment due to the low color rendering problem. In addition, the mixed light L has the optical characteristics of ultraviolet light, and the special disease symptoms can be presented by the mixed light L to prevent medical personnel from neglecting the symptoms, and to obtain relevant pathological information. Furthermore, the structure of the light processing element 16 enhances the visual range of observation. In terms of the structure of the conventional endoscope, the size of the inspection equipment that can be inserted into the human body has a certain limit. Therefore, the light processing element 16 can be used for medical personnel to view a large area, and it can also improve the irradiation efficiency without modifying the internal view. Mirror equipment can achieve the effect of large-scale irradiation.

Please refer to the fourth and fifth figures, which are a schematic diagram of the second embodiment of the present invention and a schematic diagram of a collective light source. As shown in the figure, the difference between the second embodiment of the present invention and the first embodiment is that it further includes a first lens 20, a second lens 22, a third lens 24, a fourth lens 26, and an output lens 28 . The first lens 20 is disposed between the beam splitting device 14 and the first light source 120, and receives the first light 1200 and projects it on the first beam splitter 140. The second lens 22 is disposed between the beam splitting device 14 and the detection light source 122, and receives the detection light 1220 and projects it on the second beam splitter 142. The third lens 24 is arranged between the third beam splitter 106 and the reflecting device 108, receives the second light 1020 reflected by the fifth surface 1060 and focuses on the reflecting mirror 1082 of the reflecting device 108, and receives the reflected light 1080 and transmits the second light 1020. Three beam mirror 106. The fourth lens 26 is disposed between the third beam splitter 106 and the third light source 104 and receives the third light 1040 and projects it on the third beam splitter 106. The output lens 28 is disposed between the spectroscopic device 14 and the light processing element 16, and receives the mixed light L to be concentrated and projected on the light receiving part 160.

The first lens 20, the second lens 22, and the fourth lens 26 are arranged in the same manner, so the first lens 20 is used for description. The arc surface of the first lens 20 faces the first surface 1400, and the plane of the first lens 20 faces the first light source 120. Since the first light source 120 uses a red light emitting diode as the light source, the first light 1200 has a directivity. The effect of external divergence (that is, the light emitted by the light-emitting diode is fan-shaped divergence). Therefore, the first light 1200 is first received through the first lens 20, and the first light 1200 can be converted into parallel projection through its arc surface, thereby increasing the area of the first surface 1400 that receives the first light 1200 uniformly, and effectively reflects the first light 1200. The light 1200 moves toward the light processing element 16. In addition, the third lens 24 and the output lens 28 are arranged in the same manner, so the output lens 28 is used for description. The arc surface of the output lens 28 faces the beam splitting device 14 and the flat surface faces the light processing element 16. After the mixed light rays L are mixed by the beam splitting device 14, they move in a parallel projection manner. Therefore, the curved surface of the output lens 28 first receives the mixed light L, and then focuses the mixed light L on the light receiving portion 162 of the light processing element 16 so that the light processing element 16 can effectively receive the mixed light L. Here, between the light source and the beam splitter/light processing element 16/reflecting device 108, the light is received by the lenses and the light path is converted, and an average/concentrated projection mode is adopted for subsequent components to receive/reflect/project, so as to effectively improve the light. Use efficiency: Among them, the above-mentioned lenses can be convex lenses, Fresnel lenses, or collimating lenses, which can be changed according to the conversion requirements of the optical path, which is not limited.

Please refer to Figure 6, which is a schematic diagram of the third embodiment of the present invention. As shown in the figure, the difference between the third embodiment of the present invention and the first embodiment is that it further includes a plurality of light source control devices 30, which can be arranged between the first beam splitter 140 and the first light source 120. To homogenize the first light 1200 projected by the first light source 120, which is arranged between the second beam splitter 142 and the detection light source 122, and to homogenize the detection light 1220 projected by the detection light source 122, is provided in the third beam splitter 106 and the second beam Between the light sources 102, the second light 1020 projected by the second light source 102 is uniformized, and is arranged between the third beam splitter 106 and the third light source 104, and the third light 1040 projected by the third light source 104 is uniformized.

The light source control device 30 as a light-transmitting element includes a main body 300 and at least one control unit 302. The main body 300 includes a first surface 3000 and a second surface 3002. The first surface 3000 is opposite to the second surface 3002, and the control unit 302 is a Rhombus mirrors/lenses, a rhombus mirror/lens array, microstructures, or light-transmitting elements with diffusion particles, etc., are provided on the first surface 3000 or/and the second surface 3002. The control unit 302 can determine the number of surfaces of the main body 300 according to the light path modulation requirements of the light.

In the sixth figure, the light source control device 30 is provided between the first beam splitter 140 and the first light source 120, and the control unit 302 is provided on the first surface 3000 and the second surface 3002 for illustration. The remaining light source control devices 30 are provided in other light splitters. The way between the mirror and the light source is the same, so I won't repeat it. When the first light source 120 projects the first light 1200, it first passes through the first surface 3000 of the light source control device 30. At this time, the first light 1200 passes through the control unit 302 provided on the first surface 3000 to change the light path angle projected to the main body 300. The control unit 302 connected to the second surface 3002 changes the light path angle of the first light 1200 again, and then leaves the light source control device 30 from the main body 300 and is projected onto the first beam splitter 140. The third embodiment of the present invention can also be combined with the second embodiment, that is, the light projected by the light source first passes through the light source adjusting device 30 to change the optical path, and then the lenses of the second embodiment average/concentrate the projected light on the light splitters Mirror for subsequent processing.

1: Endoscope light source module 10: White light source 100: white light 102: second light source 1020: second light 104: third light source 1040: Third Ray 106: third beam splitter 1060: Fifth Side 1062: Sixth Side 108: reflection device 1080: reflected light 1082: Mirror 1084: Phosphor 1086: Collecting lens 12: Light source device 120: First light source 1200: the first light 122: Detect light source 1220: Detect light 14: Spectroscopic device 140: The first beam splitter 1400: first side 1402: second side 142: Second beam splitter 1420: third side 1422: Fourth Side 16: light processing components 160: light receiving part 162: Light Emitting Department 20: The first lens 22: second lens 24: third lens 26: Fourth lens 28: output lens 30: Light source control device 300: body 3000: first surface 3002: second surface 302: Control Unit L: mixed light θ1: The first included angle θ2: second included angle θ3: The third included angle θ4: The fourth included angle

Figure 1: It is a schematic diagram of the first embodiment of the present invention; Figure 2: It is a schematic diagram of the spectroscopic device of the first embodiment of the present invention; Figure 3: It is a schematic diagram of a white light source according to the first embodiment of the present invention; Fourth figure: it is a schematic diagram of the second embodiment of the present invention; Figure 5: It is a schematic diagram of the integrated light source according to the second embodiment of the present invention; and Figure 6: It is a schematic diagram of the third embodiment of the present invention.

1: Endoscope light source module

10: White light source

100: white light

12: Light source device

120: First light source

1200: the first light

122: Detect light source

1220: Detect light

14: Spectroscopic device

140: The first beam splitter

142: Second beam splitter

16: light processing components

160: light receiving part

162: Light Emitting Department

L: mixed light

Claims (10)

An endoscope light source module, which includes: a white light source, including a white light ray; a light source device, including: a first light source, which includes a first light; a detection light source, which includes a detection light, the detection The light source is arranged opposite to the first light source; a light splitting device is arranged between the first light source and the detection light source, reflecting the first light and the detection light, so that the white light beam transmits through the light splitting device, and the first light , The detection light is mixed to form a mixed light; and a light processing element is arranged on one side of the light splitting device and receives the mixed light so that the mixed light has the optical characteristics of the detection light. The endoscope light source module described in claim 1, wherein the beam splitting device includes: a first beam splitter arranged on one side of the first light source to reflect the first light; and a second beam splitter The mirror is set on one side of the detection light source to reflect the detection light; wherein, the white light source is set on one side of the first beam splitter and the second beam splitter, and transmits the first beam splitter and the second beam splitter The mirror is mixed with the first light and the detection light to form the mixed light. For the endoscope light source module described in item 2 of the scope of patent application, the first beam splitter includes a first surface and a second surface, and the second beam splitter includes a third surface and a fourth surface, The first light is projected on the first beam splitter and is reflected by the first surface to be mixed with the white light beam, and the detection light is projected on the second beam splitter and is reflected by the third surface to be mixed with the white light beam. For the endoscope light source module described in item 3 of the scope of patent application, the first beam splitter and the second beam splitter are intersected, the first surface and the third surface intersect to form a first angle, and the first One side intersects the fourth side to form a second included angle, and the second side and the The third surface intersects to form a third included angle, and the second surface intersects the fourth surface to form a fourth included angle. For the endoscope light source module described in item 4 of the scope of patent application, the first included angle, the second included angle, the third included angle, and the fourth included angle are 90 degrees. The endoscope light source module described in item 2 of the scope of patent application further includes: a first lens, arranged between the light splitting device and the first light source, receiving the first light and projecting it on the first splitting light Mirror; a second lens arranged between the beam splitting device and the detection light source, receiving the detection light and projecting on the second beam splitting mirror; and an output lens provided between the beam splitting device and the light processing element, The mixed light is received and projected on the light processing element. In the endoscope light source module described in item 1 of the scope of patent application, the mixed light is white light and ultraviolet light. According to the endoscope light source module described in claim 1, wherein the light processing element includes: a light receiving part; and a light emitting part, one end of the light receiving part is opposite to the mixed light, and the other end is connected to the light emitting part The light-emitting portion is tapered from the light-receiving portion to the light-emitting portion, and the range of the light-emitting portion projecting the mixed light is above 30 degrees. According to the endoscope light source module described in claim 1, wherein the white light source includes: a second light source, including a second light; a third light source, including a third light, the second light source and The third light source is disposed oppositely; a third beam splitter includes a fifth surface and a sixth surface, the fifth surface is disposed opposite to the sixth surface, and the fifth surface is disposed on one side of the second light source. Reflecting the second light, the sixth surface is disposed on one side of the third light source to reflect the third light; and A reflecting device is arranged on one side of the fifth surface, the reflecting device includes: a reflecting mirror; and a phosphor arranged on one side of the reflecting mirror, the second light is reflected by the fifth surface and A reflected light is formed by the reflecting mirror and the phosphor, and the reflected light is then transmitted through the third beam splitter and mixed with the third light to form the white light. The endoscope light source module described in item 9 of the scope of patent application further includes: a third lens, arranged between the third beam splitter and the reflecting device, and receiving the second lens reflected by the fifth surface The light is concentrated on the phosphor, and receives the reflected light to transmit the third beam splitter; and a fourth lens is provided between the third beam splitter and the third light source, and receives the third light Projected on the third beam splitter.

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