CN210488147U - Laser speckle eliminating device and scanning projection equipment - Google Patents
Laser speckle eliminating device and scanning projection equipment Download PDFInfo
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- CN210488147U CN210488147U CN201921320970.4U CN201921320970U CN210488147U CN 210488147 U CN210488147 U CN 210488147U CN 201921320970 U CN201921320970 U CN 201921320970U CN 210488147 U CN210488147 U CN 210488147U
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Abstract
The utility model provides a eliminate laser speckle device and scanning projection equipment relates to projection equipment technical field, eliminate the laser speckle device and include: a non-polarization beam splitter, a polarization state conversion mechanism and a polarization beam combiner; the non-polarization beam splitter is used for splitting incident light in a first polarization state into a first sub-beam and a second sub-beam; the first sub-beam can enter the polarization beam combiner, and the second sub-beam can enter the polarization beam combiner after passing through the polarization state conversion mechanism; the polarization beam combiner is used for combining the first sub-beam and the second sub-beam; the polarization state conversion mechanism comprises a half-wave plate corresponding to the wavelength of incident light and is used for converting the second sub-beam passing through the half-wave plate from a first polarization state to a second polarization state, and the difference value between the length of a path taken by the second sub-beam and the length of a path taken by the first sub-beam is larger than the coherence length of the incident light, so that the coherence of the projection light beam is eliminated, and the speckle intensity is greatly reduced after synthesis.
Description
Technical Field
The utility model belongs to the technical field of projection equipment technique and specifically relates to a eliminate laser speckle device and scanning projection equipment is related to.
Background
Laser Beam Scanning (LBS) displays Laser spots incident to the center of the Laser Beam Scanning projection display line by a Scanning galvanometer (MEMS mirror), and has bright application prospects in consumer optoelectronic fields such as ar (augmented reality), vr (virtual reality) and mr (mixed reality), smart home, smart driving and the like due to the advantages of high contrast, compact structure, high integration, afocal display, portability, convenient power supply and the like.
When a laser light source with excellent coherence irradiates an optically rough surface (screen), the screen surface can be divided into a plurality of surface units, the light reflected by each unit has phase difference, and the units can interfere with each other in space to form a speckle pattern with irregularly distributed granular structures. The presence of speckle can result in the loss of a portion of the image's information content and can reduce the resolution of the image.
Therefore, speckle is a major factor that degrades image quality and resolution, and is one of the factors that restrict the development of projectors.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a eliminate laser speckle device and scanning projection equipment to the speckle that has alleviated current projection equipment and has produced influences the technical problem of image quality and resolution ratio.
In a first aspect, an embodiment of the present invention provides a laser speckle device disappears, the laser speckle device disappears includes: a non-polarization beam splitter, a polarization state conversion mechanism and a polarization beam combiner; the non-polarizing beam splitter is used for splitting incident light in a first polarization state into a first sub-beam and a second sub-beam; the first sub-beam can be incident to the polarization beam combiner, and the second sub-beam can be incident to the polarization beam combiner after passing through the polarization state conversion mechanism; the polarization beam combiner is used for combining the first sub-beam and the second sub-beam;
the polarization state conversion mechanism comprises a half-wave plate corresponding to the wavelength of incident light and is used for converting the second sub-beam passing through the half-wave plate from a first polarization state to a second polarization state, wherein one of the first polarization state and the second polarization state is a p-polarization state, and the other one of the first polarization state and the second polarization state is an s-polarization state;
the difference between the length of the path taken by the second sub-beam and the length of the path taken by the first sub-beam is greater than the coherence length of the incident light.
Further, the polarization state conversion mechanism includes: a first reflective structure and a second reflective structure;
the first reflecting structure is positioned on the propagation path of the second sub-beam, and the first reflecting structure faces the non-polarizing beam splitter and the second reflecting structure so as to reflect the second sub-beam to the second reflecting structure;
the second reflecting structure faces the first reflecting structure and the polarization beam combiner, so that the second sub-beams are reflected to the polarization beam combiner;
the half-wave plate is located between the first and second reflective structures.
Furthermore, the number of the polarization state conversion mechanisms is n, n is an integer greater than or equal to 2, and the n polarization state conversion mechanisms are arranged at intervals one by one along the direction far away from the non-polarization beam splitter;
in a direction away from the non-polarizing beam splitter,
the serial numbers of the n first reflection structures are m respectively1、m2、m3……mn；
The serial numbers of the n second reflection structures are respectively k1、k2、k3……kn；
n number of half-wave plates are respectively b1、b2、b3……bnAnd are respectively numbered with b1、b2……bnThe half-wave plate of (2) corresponds to lasers with different wavelengths respectively J1、J2、J3……JnLaser;
the number is m1And the first reflection structure of (1) and the number k1Is capable of reflecting J1Laser, and transmits J2～JnLaser;
the number is m2And the first reflection structure of (1) and the number k2Is capable of reflecting J2Laser, and transmits J3～JnLaser;
and so on;
the number is mn-1And the first reflection structure of (1) and the number kn-1Is capable of reflecting Jn-1Laser, and transmits JnLaser;
the number is mnAnd the first reflection structure of (1) and the number knIs capable of reflecting JnLaser;
so as to comprise J1、J2、J3……JnThe second sub-beam of laser light can sequentially pass through the n first reflecting structures, and J1、J2、J3……JnThe laser is reflected and separated one by one, and the n second reflection structures can separate J1、J2、J3……JnThe laser light is combined and reflected into the polarization beam combiner.
Further, the first reflecting structure and the second reflecting structure are both sheet-shaped structures;
number m1The surface of the first reflection structure facing the non-polarization beam splitter is plated with a pair J2～JnAntireflection film for laser, Pair J1The laser high reflection film is coated with a counter J on the surface back to the non-polarization beam splitter2～JnAn antireflection film for laser; number k1To (1) aOne surface of the two reflecting structures facing the polarization beam combiner is plated with a pair J2～JnAntireflection film for laser, Pair J1The laser high reflection film is coated with a pair J on the surface back to the polarization beam combiner2～JnAn antireflection film for laser;
number m2The surface of the first reflection structure facing the non-polarization beam splitter is plated with a pair J3～JnAntireflection film for laser, Pair J2The laser high reflection film is coated with a counter J on the surface back to the non-polarization beam splitter3～JnAn antireflection film for laser; number k2The second reflecting structure is plated with a pair J towards one surface of the polarization beam combiner3～JnAntireflection film for laser, Pair J2The laser high reflection film is coated with a pair J on the surface back to the polarization beam combiner3～JnAn antireflection film for laser;
and so on;
number mn-1The surface of the first reflection structure facing the non-polarization beam splitter is plated with a pair JnAntireflection film for laser, Pair Jn-1The laser high reflection film is coated with a counter J on the surface back to the non-polarization beam splitternAn antireflection film for laser; number kn-1The second reflecting structure is plated with a pair J towards one surface of the polarization beam combinernAntireflection film for laser, Pair Jn-1The laser high reflection film is coated with a pair J on the surface back to the polarization beam combinernAn antireflection film for laser;
number mnThe surface of the first reflection structure facing the non-polarization beam splitter is plated with a pair JnLaser high-reflection film; number knThe second reflecting structure is plated with a pair J towards one surface of the polarization beam combinernAnd (3) laser high-reflection film.
Further, the laser speckle eliminating device comprises a first prism and a second prism, main sections of the first prism and the second prism are both parallelograms, and internal angles of the parallelograms are 45 degrees and 135 degrees respectively;
the number of the first prisms and the number of the second prisms are both n, and the first prisms are arranged along the direction far away from the non-polarization beam splitter and are connected in sequence; the second prisms are arranged along the direction far away from the polarization beam combiner and are connected in sequence;
in a direction away from the non-polarizing beam splitter,
the serial numbers of the n first prisms are respectively f1、f2、f3……fn；
The numbers of the n second prisms are g respectively1、g2、g3……gn；
Number f1Facing the non-polarizing beam splitter and numbered b1And the surface is numbered f2The first prism is connected with one surface close to the non-polarization beam splitter, and J is plated between the first prism and the non-polarization beam splitter2～JnAntireflection film for laser, Pair J1Laser high-reflection film; number g1The second prism faces the polarization beam combiner from the surface far away from the polarization beam combiner and is numbered as b1And the surface is numbered g2The second prism is connected with one surface close to the polarization beam combiner, and J is plated between the second prism and the polarization beam combiner2～JnAntireflection film for laser, Pair J1Laser high-reflection film; and the number is f1First prism and the number b1One side of the half-wave plate is connected, and the number is b1The other side of the half-wave plate is numbered g1The second prism is connected;
number f2Facing the non-polarizing beam splitter and numbered b2And the surface is numbered f3The first prism is connected with one surface close to the non-polarization beam splitter, and J is plated between the first prism and the non-polarization beam splitter3～JnAntireflection film for laser, Pair J2Laser high-reflection film; number g2The second prism faces the polarization beam combiner from the surface far away from the polarization beam combiner and is numbered as b2And the surface is numbered g3The second prism is connected with one surface close to the polarization beam combiner, and J is plated between the second prism and the polarization beam combiner3～JnAntireflection film for laser, Pair J2Laser high-reflection film; and the number is f2First prism and the number b2One side of the half-wave plate is connected, and the number is b2The other side of the half-wave plate is numbered g2The second prism is connected;
and so on;
number fn-1Facing the non-polarizing beam splitter and numbered bn-1And the surface is numbered fnThe first prism is connected with one surface close to the non-polarization beam splitter, and J is plated between the first prism and the non-polarization beam splitternAntireflection film for laser, Pair Jn-1Laser high-reflection film; number gn-1The second prism faces the polarization beam combiner from the surface far away from the polarization beam combiner and is numbered as bn-1And the surface is numbered gnThe second prism is connected with one surface close to the polarization beam combiner, and J is plated between the second prism and the polarization beam combinernAntireflection film for laser, Pair Jn-1Laser high-reflection film; and the number is fn-1First prism and the number bn-1One side of the half-wave plate is connected, and the number is bn-1The other side of the half-wave plate is numbered gn-1The second prism is connected;
number fnFacing the non-polarizing beam splitter and numbered bnThe half-wave plate of (1); number gnThe second prism faces the polarization beam combiner from the surface far away from the polarization beam combiner and is numbered as b2The half-wave plate of (1); and the number is fnFirst prism and the number bnOne side of the half-wave plate is connected, and the number is bnThe other side of the half-wave plate is numbered gnIs connected to the second prism.
Furthermore, antireflection films are plated on the light inlet surface and the light outlet surface of the half-wave plate.
Furthermore, the number of the polarization state conversion mechanisms is three, and three half-wave plates in the three polarization state conversion mechanisms respectively correspond to red light, green light and blue light.
In a second aspect, an embodiment of the present invention provides a scanning projection apparatus, including the above laser speckle eliminating device.
Further, the scanning projection device comprises a scanning spot generator, wherein the scanning spot generator comprises a plurality of light source mechanisms and a beam combining assembly, and the beam combining assembly is used for combining the laser beams output by the plurality of light source mechanisms;
the scanning light spot generator further comprises a shaping structure, and the shaping structure is used for shaping the oval light spots emitted by the light source mechanism into round light spots.
Further, the shaping structure is located behind the beam combining assembly and is used for shaping the laser beams which are combined.
Furthermore, the number of the shaping structures is the same as that of the light source mechanisms, and the shaping structures correspond to the light source mechanisms one by one;
the shaping structure is positioned between the light source mechanism and the beam combining component, so that light emitted by the light source mechanism is shaped and then combined.
Further, the shaping structure is a prism group or a biconic lens.
Further, the scanning projection device comprises a laser wavelength temperature drift detection mechanism, and the laser wavelength temperature drift detection mechanism is used for detecting the drift amount of the laser wavelength emitted by each light source mechanism.
Further, the beam combining assembly comprises a plurality of spaced beam combining sheets or a plurality of beam combining prisms connected with each other.
Further, the scanning projection device comprises a beam expander located behind the scanning galvanometer, and the beam expander is used for increasing the angle of field of projection.
The embodiment of the utility model provides a eliminate laser speckle device, eliminate laser speckle device and include: a non-polarization beam splitter, a polarization state conversion mechanism and a polarization beam combiner. The laser light in the first polarization state enters the non-polarization beam splitter, and the non-polarization beam splitter can split the laser light into a first sub beam and a second sub beam, and the first sub beam and the second sub beam advance towards different directions; the polarization beam combiner is used for combining the first sub-beam and the second sub-beam; the polarization state conversion mechanism comprises a half-wave plate corresponding to the wavelength of incident light, the second sub-beam passing through the half-wave plate can be converted into a second polarization state from a first polarization state, and one of the first polarization state and the second polarization state is a p-polarization state, and the other is an s-polarization state; the difference between the length of the path taken by the second sub-beam and the length of the path taken by the first sub-beam is greater than the coherence length of the incident light. The laser speckle is a phenomenon of coherent superposition of scattered light generated by irradiation of coherent laser light on a diffuse reflection surface, and is essentially caused by the coherence of the laser light.
In a second aspect, an embodiment of the present invention provides a scanning projection apparatus, including the above laser speckle eliminating device. Because the embodiment of the utility model provides a scanning projection equipment has quoted foretell laser speckle device that disappears, so, the embodiment of the utility model provides a scanning projection equipment also possesses the advantage of eliminating laser speckle device.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic view of a laser speckle removing device provided by an embodiment of the present invention;
fig. 2 is a schematic view of another laser speckle reduction device provided in the embodiment of the present invention;
fig. 3 is a schematic diagram of a scanning projection apparatus according to an embodiment of the present invention;
fig. 4 is a schematic diagram of another scanning spot generator of a scanning projection apparatus according to an embodiment of the present invention.
Icon: 110-a non-polarizing beam splitter; 120-a polarization state conversion mechanism; 121-a first reflective structure; 122-a half-wave plate; 123-a second reflective structure; 130-a polarization beam combiner; 141-a first sub-beam; 142-a second sub-beam; 151-a first prism; 152-a second prism; 210-a laser diode; 220-a collimating lens; 230-an energy beam splitter; 240-biconic lens; 250-a beam combining component; 260-prism group; 300-scanning galvanometer; 400-a beam expander.
Detailed Description
The technical solution of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
As shown in fig. 1, the embodiment of the utility model provides a eliminate laser speckle device, eliminate laser speckle device and include: a non-polarization beam splitter 110, a polarization state conversion mechanism 120, and a polarization beam combiner 130. The laser light in the first polarization state enters the non-polarization beam splitter 110, which can split the laser light into a first sub-beam 141 and a second sub-beam 142, which proceed in different directions, the first sub-beam 141 can enter the polarization beam combiner 130, and the second sub-beam 142 can enter the polarization beam combiner 130 after passing through the polarization conversion mechanism 120; the polarization beam combiner 130 is configured to combine the first sub-beam 141 and the second sub-beam 142; the polarization state conversion mechanism 120 includes a half-wave plate 122 corresponding to the wavelength of the incident light, and the second sub-beam 142 passing through the half-wave plate 122 can be converted from a first polarization state to a second polarization state, one of the first polarization state and the second polarization state being a p-polarization state and the other being an s-polarization state; the difference between the length of the path followed by the second sub-beam 142 and the length of the path followed by the first sub-beam 141 is larger than the coherence length of the incident light. The laser speckle is a coherent superposition phenomenon of scattered light generated by irradiation of coherent laser light on a diffuse reflection surface, and is essentially caused by coherence of the laser light, and because the vibration directions of the first sub-beam 141 and the second sub-beam 142 are perpendicular to each other, and the optical path difference between the first sub-beam 141 and the second sub-beam 142 is greater than the coherence length of the corresponding laser light, the coherence of the projection light beam is eliminated, so that the intensity of the synthesized speckle is greatly reduced, and the imaging quality of scanning projection can be effectively improved.
It should be noted that the term "speckle reduction" as used herein refers to laser speckle reduction.
For convenience of explanation, the following description will be given taking, as an example, a laser beam having a polarization state p of a laser beam entering the laser speckle reduction device. The utility model discloses from the root cause that laser speckle formed, laser itself has the coherence promptly, proposes the combination that divides into the projection beam into the first sub-beam 141 of horizontal p polarization state and the second sub-beam 142 of perpendicular s polarization state's projection beam to make the second sub-beam 142 of perpendicular s polarization state and the optical path difference of the first sub-beam 141 of horizontal p polarization state be greater than the coherent length that corresponds the laser, eliminate projection beam's coherence, fine reduction the speckle intensity of projection image.
As shown in fig. 1, the first sub-beam 141 traveling to the right is p-polarized light, and the second sub-beam 142 traveling to the up is s-polarized light, and the p-polarized light and the s-polarized light are combined by the polarization beam combiner 130 and emitted after being combined into one light. The polarization beam combiner 130 may be a sheet structure, and one surface facing the non-polarization beam splitter 110 is coated with p-polarization antireflection films for blue light, green light, and red light, and one surface facing away from the non-polarization beam splitter 110 is coated with s-polarization antireflection films for blue light, green light, and red light, so as to combine the first sub-beam 141 and the second sub-beam 142.
The polarization beam combiner 130 may also be a beam splitter prism structure, and an antireflection film system needs to be plated on each light-transmitting surface at this time, so as to improve light energy transmission and reduce stray light.
Preferably, the beam splitting ratio of the non-polarizing beam splitter 110 may be 50:50, that is, the energy ratio of the split first sub-beam 141 and the second sub-beam 142 is 1: 1. other non-polarizing beam splitters 110 close to this ratio may also be used in the laser speckle reduction apparatus. The non-polarization beam splitter 110 has a beam splitting surface forming an angle of 45 degrees with the incident laser light, the first sub-beam 141 is transmitted according to the traveling direction of the original laser light, and the second sub-beam 142 is reflected according to the direction perpendicular to the original laser light. The non-polarizing beam splitter 110 is a conventional optical element.
The non-polarization beam splitter 110 and the polarization beam combiner 130 may be both on an extension line of the traveling path of the original laser light, and the polarization conversion mechanism 120 includes: a first reflecting structure 121 and a second reflecting structure 123, wherein the first reflecting structure 121 is located on the propagation path of the second sub-beam 142, the incident angle of the second sub-beam 142 may be 45 °, and the first reflecting structure 121 faces the non-polarizing beam splitter 110 and the second reflecting structure 123, so as to reflect the second sub-beam 142 to the second reflecting structure 123; the second reflecting structure 123 faces the first reflecting structure 121 and the polarization beam combiner 130, and the incident angle of the second sub-beam 142 may be 45 °, so that the second sub-beam 142 is reflected toward the polarization beam combiner 130; the half-wave plate is located between the first and second reflective structures 121 and 123. The first sub-beam 141 directly enters the polarization beam combiner 130 from the non-polarization beam splitter 110, and the second sub-beam 142 enters the polarization beam combiner 130 after being reflected from two sides, so that the optical path of the second sub-beam 142 is extended. By adjusting the distance between the first reflecting structure 121 and the non-polarizing beam splitter 110 and the distance between the second reflecting structure 123 and the polarizing beam combiner 130, the optical path length difference between the first sub-beam 141 and the second sub-beam 142 can be adjusted.
The number of the polarization state conversion mechanisms 120 is n, n is an integer greater than or equal to 2, and the n polarization state conversion mechanisms 120 are arranged at intervals one by one along the direction far away from the non-polarization beam splitter 110; the n first reflective structures 121 are numbered m respectively in a direction away from the non-polarizing beam splitter 1101、m2、m3……mn(ii) a The n second reflective structures 123 are numbered k1、k2、k3……kn(ii) a The n half-wave plates 122 are respectively numbered b1、b2、b3……bnAnd are respectively numbered with b1、b2……bnThe half-wave plate 122 corresponds to lasers with different wavelengths respectively J1、J2、J3……JnLaser; the number is m1And the first reflective structure 121 and number k1Can reflect J1Laser, and transmits J2～JnLaser; the number is m2And the first reflective structure 121 and number k2Can reflect J2Laser, and transmits J3～JnLaser; by analogy, the number is mn-1And the first reflective structure 121 and number kn-1Can reflect Jn-1Laser, and transmits JnLaser; the number is mnAnd the first reflective structure 121 and number knCan reflect JnAnd (4) laser. Comprises J1、J2、J3……JnThe second sub-beam 142 of laser light can pass through the n first reflecting structures 121 in sequence, and J1、J2、J3……JnThe laser light is reflected one by one to be separated, and n is a second reflection structure 123 capable of separating J1、J2、J3……JnThe laser light is combined and reflected into the polarization beam combiner 130.
In this embodiment, the number of the polarization conversion mechanisms 120 may be three, wherein the lights corresponding to the three half-wave plates 122 are blue light, green light and red light, respectively. When the second sub-beam 142 including blue light, green light, and red light is vertically irradiated to the first reflecting structure 121, the blue light is reflected toward the first half-wave plate 122, and the polarization state of the blue light is changed into s-polarized light; the green light and the red light are transmitted through the first reflective structure 121 and irradiated onto the second first reflective structure 121, and at this time, the green light is reflected by the second first reflective structure 121 to the second half-wave plate 122, and the green light is also converted from the p-polarization state to the s-polarization state; the red light passes through the second first reflective structure 121 and then illuminates the third first reflective structure 121, the red light is reflected toward the third half-wave plate 122, and the red light is also converted into s-polarization. The blue light, the green light and the red light respectively irradiated onto the three parallel second reflecting structures 123 may be irradiated onto the polarization beam combiner 130 after being combined.
Specifically, the first reflective structure 121 and the second reflective structure 123 may be both sheet-shaped structures; number m1The first reflecting structure 121 facing the non-polarizing beam splitter 110 is plated with a pair J2～JnAntireflection film for laser, Pair J1The laser high reflection film and the surface opposite to the non-polarization beam splitter 110 are plated with a counter J2～JnAn antireflection film for laser; number k1The second reflecting structure 123 facing the polarization beam combiner 130 is plated with a pair J2～JnAntireflection film for laser, Pair J1The laser high reflection film and the surface back to the polarization beam combiner 130 are plated with a pair J2～JnAn antireflection film for laser; number m2The first reflecting structure 121 facing the non-polarizing beam splitter 110 is plated with a pair J3～JnAntireflection film for laser, Pair J2The laser high reflection film and the surface opposite to the non-polarization beam splitter 110 are plated with a counter J3～JnAn antireflection film for laser; number k2The second reflecting structure 123 facing the polarization beam combiner 130 is plated with a pair J3～JnAntireflection film for laser, Pair J2The laser high reflection film and the surface back to the polarization beam combiner 130 are plated with a pair J3～JnAn antireflection film for laser; number mn-1The first reflecting structure 121 facing the non-polarizing beam splitter 110 is plated with a pair JnAntireflection film for laser, Pair Jn-1The laser high reflection film and the surface opposite to the non-polarization beam splitter 110 are plated with a counter JnAn antireflection film for laser; number kn-1The second reflecting structure 123 facing the polarization beam combiner 130 is plated with a pair JnAntireflection film for laser, Pair Jn-1The laser high reflection film and the surface back to the polarization beam combiner 130 are plated with a pair JnAn antireflection film for laser; number mnTowards the first reflecting structure 121A pair J is plated to one surface of the non-polarizing beam splitter 110nLaser high-reflection film; number knThe second reflecting structure 123 facing the polarization beam combiner 130 is plated with a pair JnAnd (3) laser high-reflection film.
The number of the polarization conversion mechanisms 120 may be three, wherein the three half-wave plates 122 correspond to blue light, green light, and red light, respectively. When entering the laser speckle reduction device, the laser beam including blue light, green light, and red light is divided into two equal energy parts, a first sub-beam 141 and a second sub-beam 142 by the non-polarizing beam splitter 110, the first sub-beam 141 continues to propagate forward, and the second sub-beam 142 propagates downward. At this time, the polarization directions of the forward and downward propagating beams remain unchanged and are still horizontally p-polarized.
The second sub-beam 142 traveling downward sequentially passes through the three first reflective structures 121, and the three first reflective structures 121 are correspondingly used for separating blue light, green light and red light sequentially. The upper surface of the first reflection structure 121 is plated with a green light and red light antireflection film, the blue light high reflection film, and the lower surface is plated with a green light and red light antireflection film. The upper surface of the second first reflective structure 121 is coated with a red light antireflection film, a green light highly reflective film, and the lower surface is coated with a red light antireflection film. The upper surface of the third first reflective structure 121 is plated with a red high-reflectivity film. The angle between the second sub-beam 142 and the first reflecting structure 121 is 45 °, or other angles are selected according to actual requirements.
After color separation by the first reflective structure 121, each color light sequentially vertically passes through the corresponding half-wave plate 122, and the horizontal p-polarized light is converted into vertical s-polarized light. The front and back surfaces of the half-wave plate 122 are plated with antireflection film systems to reduce ghost imaging and improve the light energy utilization rate.
After the light of each color is subjected to polarization conversion, the light of each color sequentially passes through the three second reflecting structures 123, and finally the blue light, the green light and the red light are synthesized into white light. Wherein, the upper surface of the third second reflective structure 123 far away from the polarization beam combiner 130 is plated with a red high-reflection film. The lower surface of the second reflecting structure 123 is coated with a red light antireflection film, and the upper surface thereof is coated with a red light antireflection film and a green light highly-reflecting film. The lower surface of the first second reflecting structure 123 is plated with an antireflection film for green light and red light; the upper surface is plated with a green light and red light antireflection film and a blue light high-reflection film. The second sub-beam 142 passing through the half-wave plate 122 forms an angle of 45 ° with the second reflecting structure 123, or other angles are selected according to practical requirements. Because the first reflecting structure 121 and the second reflecting structure 123 have a distance from the non-polarizing beam splitter 110 and the polarizing beam combiner 130, respectively, the path traveled by the twice reflected second sub-beam 142 is certainly longer than the path traveled by the first sub-beam 141, and the positions of the first reflecting structure 121 and the second reflecting structure 123 are adjusted according to the coherence length of the color light to be corrected, so that the optical path difference between the second sub-beam 142 and the first sub-beam 141 is longer than the coherence length of the corresponding color light.
According to the laser principle, the coherence length L of the lasercCan be represented as Lc＝λ2And/Δ λ, wherein λ and Δ λ are the laser central wavelength and the laser line width, respectively. From the above formula, when the optical path difference between the two laser beams is larger than the coherence length of the laser beam, the two laser beams are no longer coherent, and the two laser beams are no longer interfered. Taking a certain laser J of Osram as an example, the emergent central wavelength is 638nm, the laser line width is 1nm, the coherent length is 0.407mm theoretically, and the coherence of two beams of light can be eliminated as long as the optical path difference is larger than 1mm practically.
The intensity of the two beams of light waves with equal intensity after superposition can be expressed as:
Ip＝2I0+2I0cosδp
wherein, I0Representing the intensity, delta, of a beam of lightpIndicating the phase difference of the two columns of light waves. When p-polarized light is divided into p-light and s-light with equal intensity, the intensity after superposition can be expressed as
Ip+s＝2I0+I0cosδs+I0cosδp
Wherein, deltapAnd deltasRespectively representing the phase difference of two columns of light waves of s light and p light. Since the vibration directions of the horizontal p-component light and the vertical s-component light are perpendicular to each other, δpAnd deltasThe method has no correlation, so that the speckle intensity after synthesis is greatly reduced, and the imaging quality of scanning projection can be effectively improved.
As shown in fig. 2, the first and second reflecting structures 121 and 123 may be formed by a prism structure in addition to the divided sheets of the sheet structure. Specifically, the laser speckle eliminating device comprises a first prism 151 and a second prism 152, main sections of the first prism 151 and the second prism 152 are both parallelograms, and internal angles of the parallelograms are 45 degrees and 135 degrees respectively; the number of the first prisms 151 and the second prisms 152 is n, and the first prisms 151 are arranged along a direction away from the non-polarizing beam splitter 110 and are connected in sequence; the second prisms 152 are arranged along a direction far away from the polarization beam combiner 130 and are connected in sequence; the n first prisms 151 are numbered f respectively in a direction away from the non-polarizing beam splitter 1101、f2、f3……fn(ii) a The n second prisms 152 are respectively numbered g1、g2、g3……gn(ii) a Number f1Faces the non-polarizing beam splitter 110 away from the non-polarizing beam splitter 110 and is numbered b1And the face is numbered f2The first prism 151 is connected to a surface close to the non-polarizing beam splitter 110, and J is plated between the two2～JnAntireflection film for laser, Pair J1Laser high-reflection film; number g1Faces the polarization beam combiner 130 and is numbered b1And the face is numbered g with2The second prism 152 is connected to a surface of the polarization beam combiner 130, and J is plated between the two2～JnAntireflection film for laser, Pair J1Laser high-reflection film; and the number is f1First prism 151 and the number b1Is connected to one side of the half-wave plate 122, which is numbered b1The other side of the half-wave plate 122 and the number g1Second prism 152; number f2Faces the non-polarizing beam splitter 110 away from the non-polarizing beam splitter 110 and is numbered b2And the face is numbered f3The first prism 151 is connected to a surface close to the non-polarizing beam splitter 110, and J is plated between the two3～JnAntireflection film for laser, Pair J2Laser high-reflection film; number g2Faces the polarization beam combiner 130 and is numbered b2And the face is numbered g with3The second prism 152 is connected to a surface of the polarization beam combiner 130, and J is plated between the two3～JnAntireflection film for laser, Pair J2Laser high-reflection film; and the number is f2First prism 151 and the number b2Is connected to one side of the half-wave plate 122, which is numbered b2The other side of the half-wave plate 122 and the number g2Second prism 152; and so on; number fn-1Faces the non-polarizing beam splitter 110 away from the non-polarizing beam splitter 110 and is numbered bn-1And the face is numbered fnThe first prism 151 is connected to a surface close to the non-polarizing beam splitter 110, and J is plated between the twonAntireflection film for laser, Pair Jn-1Laser high-reflection film; number gn-1Faces the polarization beam combiner 130 and is numbered bn-1And the face is numbered g withnThe second prism 152 is connected to a surface of the polarization beam combiner 130, and J is plated between the twonAntireflection film for laser, Pair Jn-1Laser high-reflection film; and the number is fn-1First prism 151 and the number bn-1Is connected to one side of the half-wave plate 122, which is numbered bn-1The other side of the half-wave plate 122 and the number gn-1Second prism 152; number fnFaces the non-polarizing beam splitter 110 away from the non-polarizing beam splitter 110 and is numbered bnThe half-wave plate 122; number gnFaces the polarization beam combiner 130 and is numbered b2The half-wave plate 122; and the number is fnFirst prism 151 and the number bnIs connected to one side of the half-wave plate 122, which is numbered bnThe other side of the half-wave plate 122 and the number gnIs connected to the second prism 152.
In the above embodiment, the package structure of the laser speckle eliminating device is more compact, and the optical elements can be connected by gluing. The second sub-beam 142 traveling downward sequentially passes through the three first prisms 151, and the three first prisms 151 perform a light splitting function, which is sequentially used to separate blue light, green light, and red light. Wherein, the lower surface of the first prism 151 is connected with the upper surface of the second first prism 151, and an antireflection film for green light and red light, a high reflection film for blue light are plated between the first prism 151 and the second prism; the connecting surface of the second first prism 151 and the third first prism 151 is plated with a red light antireflection film and a green light highly reflective film; the surface of the third first prism 151 away from the non-polarizing beam splitter 110 is 45 ° to the second sub-beam 142, and no coating is required because the condition for total reflection is satisfied.
After color separation by the three first prisms 151, each color light passes through the corresponding half-wave plate 122 in sequence, and the horizontal p-polarized light is converted into vertical s-polarized light. The front and back surfaces of the half-wave plate 122 are plated with antireflection film systems to reduce ghost imaging and improve the light energy utilization rate.
The light of each color passes through three second prisms 152 after polarization conversion, the second prisms 152 and the first prisms 151 are symmetrical relative to the half-wave plate 122, and the blue light, the green light and the red light are finally synthesized into white light. The second prism 152, which is farthest from the polarization beam combiner 130, of the third second prism 152 meets the total reflection occurrence condition, and no film is required to be coated; the connecting surface of the second prism 152 and the third prism 152 is plated with a red light antireflection film and a green light highly reflective film; the connecting surfaces of the first second prisms 152 and the second first prisms 151 are plated with green and red antireflection films and a blue high-reflection film. Since the prism has a certain thickness, the thickness of the prism is adjusted so that the optical path difference between the second sub-beam 142 and the first sub-beam 141 is greater than the correlation length of the corresponding color light.
The red, green and blue light provides three primary colors of red, green and blue (RGB) for the whole projector, and the white light is synthesized by beam combination to realize full-color display. When the laser incident into the laser speckle eliminating device contains non-imaging light, for example, the laser includes an infrared detection laser, which provides an infrared detection light source for the whole projector, and human-computer interaction is realized with the aid of the electronic control module, then an infrared detection laser antireflection film or a high-reflection film can be plated on the first reflection structure 121 and the second reflection structure 123 according to requirements, so that the infrared detection laser can enter the polarization beam combiner 130 through the plurality of first reflection structures 121 and the plurality of second reflection structures 123 in sequence. The speckle eliminating process of the laser speckle eliminating device does not influence the transmission of the infrared detection laser. One possible combination of emission wavelengths for the common three primary colors RGB and the infrared detection laser is 635nm, 525nm, 450nm and 825 nm. The first reflecting structure 121, the half-wave plate 122 and the second reflecting structure 123 are reasonably arranged according to the wavelength combination.
Since the first and second reflecting structures 121 and 123 are formed of prisms, the non-polarizing beam splitter 110 and the polarizing beam combiner 130 may also be prism structures with an interior angle of 45 ° -90 ° -45 °. The hypotenuse of the non-polarizing beam splitter 110 is connected to one face of the first prism 151 and the hypotenuse of the polarizing beam combiner 130 is connected to one face of the first second prism 152. The laser speckle eliminating device can be integrated.
As shown in fig. 3 and fig. 4, an embodiment of the present invention provides a scanning projection apparatus, which includes the above-mentioned laser speckle reduction device. Because the embodiment of the utility model provides a scanning projection equipment has quoted foretell laser speckle device that disappears, so, the embodiment of the utility model provides a scanning projection equipment also possesses the advantage of eliminating laser speckle device.
The scanning projection device comprises a scanning spot generator, wherein the scanning spot generator comprises a plurality of light source mechanisms and a beam combining component 250, and the beam combining component 250 is used for combining laser beams output by the plurality of light source mechanisms; the scanning light spot generator further comprises a shaping structure, and the shaping structure is used for shaping the oval light spots emitted by the light source mechanism into round light spots.
The light source mechanism includes a laser and a collimating lens 220, the collimating lens 220 for collimating a light beam emitted by the laser, which may be a laser diode 210. In the present embodiment, the laser diodes 210 in the plurality of laser mechanisms may be laser diodes 210 of red, green, and blue light, respectively, and an infrared laser diode 210 for infrared detection. The red, green and blue laser diodes 210 provide the three primary colors of red, green and blue (RGB) for the whole projector, and the combined beams are combined into white light to realize full-color display. The infrared laser diode 210 provides an infrared detection light source for the whole projector, and human-computer interaction is realized with the aid of the electronic control module, and the common three primary colors of RGB and one possible combination of emission wavelengths of the infrared detection laser are 635nm, 525nm, 450nm and 825 nm. Other wavelength combinations can also be selected according to actual needs.
The collimating lens 220 may be an aspheric lens, and may collimate the light beams emitted from the laser diode 210, which have a certain divergence angle in two orthogonal directions, into an elliptical spot having no optical power and a divergence angle of 0. The front and back surfaces of the collimating lens 220 are plated with antireflection film systems to reduce ghost imaging and improve light energy utilization. Due to the structural design of the edge-emitting laser diode 210, the light-emitting region is a nearly rectangular region, the divergence angles of the light beams emitted from the laser diode 210 in two orthogonal directions are different, and the divergence angle of the light beams emitted from the long edge of the rectangular region is smaller, which is called as the slow axis direction; the divergence angle of the light beam emitted from the short side of the rectangular area is large, which is called the fast axis direction. Taking an Osram laser diode 210 as an example, the divergence angle of the laser emission in the horizontal and vertical directions is θ∥xθ⊥6.3 ° x22.5 °. Therefore, after propagating for a certain distance, the diverging light beam emitted from the laser diode 210 becomes an elliptical light spot after being collimated by the collimating lens 220.
The collimating lens 220 may be an aspheric collimating lens 220 of molded plastic and molded glass. Wherein, for the molded plastic, the absolute value R of the curvature radius of the left surface light incident surfaceLSatisfies the following conditions: 2<RL<10mm, absolute value R of curvature radius of right surface light-emitting surfaceRSatisfies the following conditions: 1<RR<2.5mm, and the absolute value of the ratio of the radius of curvature of the left surface to the radius of curvature of the right surface is 1.5<RL/RR<4.5. For molded glass, the absolute value of the radius of curvature of the left surface, RLSatisfies the following conditions: 2<RL<20mm, absolute value of radius of curvature of right surface RRSatisfy the requirement of：1<RR<2.5mm, absolute value of the ratio of the radius of curvature of the left surface to the radius of curvature of the right surface 2<RL/RR<15。
The beam combining assembly 250 includes a plurality of spaced beam combining sheets or a plurality of beam combining prisms connected to each other.
When the number of the laser diodes 210 is four, the laser diodes are an infrared laser diode 210, a red laser diode 210, a green laser diode 210, and a blue laser diode 210 from left to right. For simplicity of description, Red light is abbreviated Red, Green light is abbreviated Green, Blue light is abbreviated Blue, infrared light is abbreviated IR, and the laser diode 210 is abbreviated LD in the following description.
The four beam combining sheets corresponding to the four LDs are sequentially a first beam combining sheet, a second beam combining sheet, a third beam combining sheet and a fourth beam combining sheet from left to right. And one surface of the first beam combining sheet facing the IRLD is plated with an IR high-reflection film. And one surface of the second beam combining sheet facing the first beam combining sheet is plated with an IR antireflection film, and one surface of the second beam combining sheet facing the RedLD is plated with an IR antireflection film and a Red high-reflection film. And one surface of the third beam combining sheet facing the second beam combining sheet is plated with an IR and Red antireflection film, one surface of the third beam combining sheet facing the GreenLD is plated with an IR and Red antireflection film, and the Green high-reflection film. And one surface of the fourth beam combining sheet facing the third beam combining sheet is plated with IR, Red and Green antireflection films, and one surface of the fourth beam combining sheet facing the Blue LD is plated with the IR, Red and Green antireflection films and a Blue high-reflection film.
In another embodiment, the beam combining assembly 250 includes a plurality of beam combining prisms coupled to one another. The number of the beam combining prisms can be four, acute angles of the first three beam combining prisms are 45 degrees, and obtuse angles of the first three beam combining prisms are 135 degrees. The angle of the fourth composite prism is 45-90-45 degrees. One surface of the beam combining prism facing the corresponding laser diode 210 is plated with an antireflection film system, so that ghost imaging is reduced, and the light energy utilization rate is improved.
The four beam-combining prisms from left to right are respectively a first beam-combining prism, a second beam-combining prism, a third beam-combining prism and a fourth beam-combining prism. One surface of the first beam combining prism unit, which faces the IRLD, can be totally reflected during working, and does not need to be coated; the connecting surface of the second beam combining prism facing the first beam combining prism faces the RedLD, and is plated with an IR antireflection film and a Red high-reflection film. One surface of the second beam combining prism, which faces to the first beam combining prism, is plated with an IR (infrared) antireflection film and a Red (Red) high-reflection film, and the surface faces to the RedLD; one surface of the second beam combining prism facing the third beam combining prism is plated with an IR and Red antireflection film and a Green high-reflection film. The third beam combining prism faces to one surface of the second beam combining prism, an IR and Red antireflection film and a Green high-reflection film are plated on the third beam combining prism, and the surface faces to the GreenLD; one surface of the third beam combining prism facing to the fourth horizontal and vertical prisms is plated with IR, Red and Green antireflection films and a Blue high-reflection film. The fourth beam combining prism faces to one surface of the third beam combining prism, an IR (infrared), Red (Red) and Green (Green) antireflection film and a Blue high-reflection film are plated, and the surface faces to a Blue LD (laser diode); and the exit surface of the fourth beam combining prism is plated with IR and Red, Green and Blue antireflection films. The plurality of laser diodes 210 under the beam combining component 250 can be respectively irradiated onto the corresponding beam combining prisms, and the beam combining component combines a plurality of beams of light into a beam of white light.
The number of the shaping structures may be one, and the shaping structure is located behind the beam combining assembly 250 and is used for shaping the combined laser. The shaping structure may be a prism assembly 260 or a biconic lens 240. Taking the shaping structure as the prism group 260 as an example, the prism group 260 may include a first shaping prism and a second shaping prism, of which two main sections are quadrilateral, and an incident beam of the combined laser is incident to the first shaping prism at a certain angle and is emitted vertically; then the light enters the second shaping prism at a certain angle and is emitted vertically. The light incident surface and the light emergent surface of the second shaping prism are both plated with antireflection film systems so as to reduce ghost imaging and improve the utilization rate of light energy. If the size of the actually used LD in the horizontal direction is smaller than that in the vertical direction after being collimated by the collimating lens 220, beam expansion needs to be performed in the horizontal direction, and at this time, incident light is obliquely incident into the prism and is emitted vertically; if the actual LD is collimated and the size in the horizontal direction is larger than that in the vertical direction, the beam is required to be contracted in the horizontal direction, and at this time, the incident light should perpendicularly enter the prism and obliquely exit at a certain angle.
The number of the shaping structures is the same as that of the light source mechanisms, and the shaping structures correspond to the light source mechanisms one by one; the shaping structure is located between the light source mechanism and the beam combining assembly 250, so that light emitted by the light source mechanism is shaped and then combined.
In this embodiment, the number of the shaping structures is the same as that of the light source mechanisms, and the divergence angle of each color light is different, so that the size of the formed elliptical light spot is different, and the light emitted by each light source mechanism can be shaped into a circular light spot by the shaping structures corresponding to each other one by one, and then the light beams are combined, so that the obtained light beams are closer to the circular light spot. In this embodiment, the shaping structure may be a biconic lens 240, and the biconic lens 240 is an afocal optical element and is mainly used to shape the light beam, i.e., to shape the elliptical light beam into a circular light beam. The shaping biconic lens 240 only narrows or expands the beam in one direction and does not contribute to the beam in the other orthogonal direction. The light inlet and outlet surfaces of the shaping biconic lens 240 are plated with antireflection film systems, so that ghost imaging is reduced, and the light energy utilization rate is improved. Table 1 shows the structural parameters of a biconic shaping lens with a reduction ratio of 0.67 for RGB color light. Wherein the curvature radius ratio of the biconic reshaping lens meets 2/3<RL/RR<2。
TABLE 3 parameters of biconic shaping lenses
| Radius of | Thickness of | Material | Constant of cone | |
| Light incident surface | 3.6 | 3.526 | H-K9L | -0.318 |
| Light emitting surface | 2.4 | / | / | / |
The scanning projection device comprises a laser wavelength temperature drift detection mechanism, and the laser wavelength temperature drift detection mechanism is used for detecting the drift amount of the laser wavelength emitted by each light source mechanism. The laser wavelength temperature drift detection mechanism comprises an energy beam splitter 230 and a detection photodiode, wherein the energy beam splitter 230 can be a Schottky N-BK7 or a Duoming CDGM H-K9L glass parallel plate which is obliquely arranged at an angle of 45 degrees, and about 1% of energy is divided to enter the detection photodiode so as to monitor the drift of the emission wavelength of each color light LD along with the change of temperature. The front and back surfaces of the parallel glass plates are polished with high precision, the light incident surface is not coated with a film, and the light emergent surface is coated with an antireflection film system, so that ghost imaging is reduced, and the light energy utilization rate is improved. The inclination angle of the glass flat plate can be adjusted to realize different beam splitting ratios, namely the glass parallel flat plate can be arranged at inclination angles of 40 degrees, 35 degrees, 30 degrees, 25 degrees and the like according to requirements.
The scanning projection device comprises a scanning galvanometer 300, which modulates light spots incident to the center of the galvanometer in the horizontal and vertical directions and scans and images according to a progressive scanning working mode.
The scanning projection device comprises a beam expander 400 positioned behind the scanning galvanometer 300, wherein the beam expander 400 is used for increasing the angle of view of the projection. After passing through the beam expander 400, the scanning projection beam emitted from the scanning galvanometer 300 increases the angle of field of projection, reduces the projection ratio, and can obtain a larger projection image at a smaller projection distance. The beam expander 400 is schematically illustrated as a concave lens, and may actually be composed of a double cemented lens consisting of a curved lens and a plurality of free-form lens groups.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.
Claims (15)
1. A laser speckle reduction apparatus, comprising: a non-polarization beam splitter (110), a polarization state conversion mechanism (120), and a polarization beam combiner (130); the non-polarizing beam splitter (110) is configured to split incident light in a first polarization state into a first sub-beam (141) and a second sub-beam (142); the first sub-beam (141) can enter the polarization beam combiner (130), and the second sub-beam (142) can enter the polarization beam combiner (130) after passing through the polarization state conversion mechanism (120); the polarization beam combiner (130) is used for combining the first sub-beam (141) and the second sub-beam (142);
the polarization state conversion mechanism (120) comprises a half-wave plate (122) corresponding to the wavelength of the incident light and is used for converting the second sub-beam (142) passing through the half-wave plate (122) from a first polarization state to a second polarization state, wherein one of the first polarization state and the second polarization state is a p-polarization state, and the other one of the first polarization state and the second polarization state is an s-polarization state;
the difference between the length of the path followed by the second sub-beam (142) and the length of the path followed by the first sub-beam (141) is larger than the coherence length of the incident light.
2. The laser speckle reduction apparatus according to claim 1, wherein the polarization state conversion mechanism (120) comprises: a first reflective structure (121) and a second reflective structure (123);
the first reflecting structure (121) is located on the propagation path of the second sub-beam (142), and the first reflecting structure (121) faces the non-polarizing beam splitter (110) and the second reflecting structure (123) to reflect the second sub-beam (142) towards the second reflecting structure (123);
the second reflecting structure (123) faces the first reflecting structure (121) and the polarization beam combiner (130) to reflect the second sub-beam (142) towards the polarization beam combiner (130);
the half-wave plate is located between the first (121) and second (123) reflective structures.
3. The laser speckle device as claimed in claim 2, wherein the number of the polarization state conversion mechanisms (120) is n, n is an integer greater than or equal to 2, and the n polarization state conversion mechanisms (120) are arranged at intervals one by one along a direction away from the non-polarization beam splitter (110);
in a direction away from the non-polarizing beam splitter (110),
the number of the n first reflection structures (121) is m1、m2、m3……mn；
The n second reflection structures (123) are respectively numbered as k1、k2、k3……kn；
n half-wave plates (122) are respectively numbered as b1、b2、b3……bnAnd are respectively numbered with b1、b2……bnThe half-wave plate (122) of (A) corresponds to laser beams of different wavelengths respectively being LD1、LD2、LD3……LDnLaser;
the number is m1And a first reflective structure (121) numbered k1Can reflect the LD1Laser, and transmits LD2～LDnLaser;
the number is m2And a first reflective structure (121) numbered k2Can reflect the LD2Laser, and transmits LD3～LDnLaser;
and so on;
the number is mn-1And a first reflective structure (121) numbered kn-1Can reflect the LDn-1Laser, and transmits LDnLaser;
the number is mnAnd a first reflective structure (121) numbered knCan reflect the LDnLaser;
so as to include LD1、LD2、LD3……LDnThe second sub-beam (142) of laser light can sequentially pass through the n first reflecting structures (121), and the LD1、LD2、LD3……LDnLaser beams are reflected and separated one by one, and n second reflection structures (123) can separate the separated LD1、LD2、LD3……LDnThe laser light is combined and reflected into a polarization beam combiner (130).
4. The laser speckle reduction device according to claim 3, wherein the first and second reflective structures (121, 123) are each a sheet-like structure;
number m1Is plated with a surface facing the non-polarizing beam splitter (110) to the LD2～LDnAntireflection film for laser, and Laser Diode (LD)1The laser high reflection film and the surface back to the non-polarization beam splitter (110) are plated with a Laser Diode (LD)2～LDnAn antireflection film for laser; number k1The surface of the second reflection structure (123) facing the polarization beam combiner (130) is plated with a pair of LD2～LDnAntireflection film for laser, and Laser Diode (LD)1The laser high reflection film and the surface back to the polarization beam combiner (130) are plated with a pair LD2～LDnAn antireflection film for laser;
number m2Is plated with a surface facing the non-polarizing beam splitter (110) to the LD3～LDnAntireflection film for laser, and Laser Diode (LD)2The laser high reflection film and the surface back to the non-polarization beam splitter (110) are plated with a Laser Diode (LD)3～LDnAn antireflection film for laser; number k2Towards said combined polarization beamOne surface of the device (130) is plated with a pair LD3～LDnAntireflection film for laser, and Laser Diode (LD)2The laser high reflection film and the surface back to the polarization beam combiner (130) are plated with a pair LD3～LDnAn antireflection film for laser;
and so on;
number mn-1Is plated with a surface facing the non-polarizing beam splitter (110) to the LDnAntireflection film for laser, and Laser Diode (LD)n-1The laser high reflection film and the surface back to the non-polarization beam splitter (110) are plated with a Laser Diode (LD)nAn antireflection film for laser; number kn-1The surface of the second reflection structure (123) facing the polarization beam combiner (130) is plated with a pair of LDnAntireflection film for laser, and Laser Diode (LD)n-1The laser high reflection film and the surface back to the polarization beam combiner (130) are plated with a pair LDnAn antireflection film for laser;
number mnIs plated with a surface facing the non-polarizing beam splitter (110) to the LDnLaser high-reflection film; number knThe surface of the second reflection structure (123) facing the polarization beam combiner (130) is plated with a pair of LDnAnd (3) laser high-reflection film.
5. The laser speckle elimination device according to claim 3, wherein the laser speckle elimination device comprises a first prism (151) and a second prism (152), the main cross sections of the first prism (151) and the second prism (152) are parallelograms, and the inner angles of the parallelograms are 45 degrees and 135 degrees respectively;
the number of the first prisms (151) and the number of the second prisms (152) are both n, and the first prisms (151) are arranged along the direction far away from the non-polarization beam splitter (110) and are connected in sequence; the second prisms (152) are arranged along the direction far away from the polarization beam combiner (130) and are connected in sequence;
in a direction away from the non-polarizing beam splitter (110),
the n first prisms (151) are numbered f1、f2、f3……fn；
The weave of n second prisms (152)Numbers are g respectively1、g2、g3……gn；
Number f1Faces the non-polarizing beam splitter (110) away from the non-polarizing beam splitter (110) and is numbered b1And the face is numbered f2The first prism (151) is connected with one surface close to the non-polarization beam splitter (110) and is plated with an LD2～LDnAntireflection film for laser, and Laser Diode (LD)1Laser high-reflection film; number g1Faces the polarization beam combiner (130) from the surface of the polarization beam combiner (130) of the second prism (152) and is numbered b1And the face is numbered g2The second prism (152) is connected with one surface close to the polarization beam combiner (130), and an LD is plated between the two2～LDnAntireflection film for laser, and Laser Diode (LD)1Laser high-reflection film; and the number is f1And the number b is1Is connected with one side of the half-wave plate (122), and the number b is1The other surface of the half-wave plate (122) and the number g1Is connected to the second prism (152);
number f2Faces the non-polarizing beam splitter (110) away from the non-polarizing beam splitter (110) and is numbered b2And the face is numbered f3The first prism (151) is connected with one surface close to the non-polarization beam splitter (110) and is plated with an LD3～LDnAntireflection film for laser, and Laser Diode (LD)2Laser high-reflection film; number g2Faces the polarization beam combiner (130) from the surface of the polarization beam combiner (130) of the second prism (152) and is numbered b2And the face is numbered g3The second prism (152) is connected with one surface close to the polarization beam combiner (130), and an LD is plated between the two3～LDnAntireflection film for laser, and Laser Diode (LD)2Laser high-reflection film; and the number is f2And the number b is2Is connected with one side of the half-wave plate (122), and the number b is2The other surface of the half-wave plate (122) and the number g2Second prism (a)152) Connecting;
and so on;
number fn-1Faces the non-polarizing beam splitter (110) away from the non-polarizing beam splitter (110) and is numbered bn-1And the face is numbered fnThe first prism (151) is connected with one surface close to the non-polarization beam splitter (110) and is plated with an LDnAntireflection film for laser, and Laser Diode (LD)n-1Laser high-reflection film; number gn-1Faces the polarization beam combiner (130) from the surface of the polarization beam combiner (130) of the second prism (152) and is numbered bn-1And the face is numbered gnThe second prism (152) is connected with one surface close to the polarization beam combiner (130), and an LD is plated between the twonAntireflection film for laser, and Laser Diode (LD)n-1Laser high-reflection film; and the number is fn-1And the number b isn-1Is connected with one side of the half-wave plate (122), and the number b isn-1The other surface of the half-wave plate (122) and the number gn-1Is connected to the second prism (152);
number fnFaces the non-polarizing beam splitter (110) away from the non-polarizing beam splitter (110) and is numbered bnThe half-wave plate (122); number gnFaces the polarization beam combiner (130) from the surface of the polarization beam combiner (130) of the second prism (152) and is numbered b2The half-wave plate (122); and the number is fnAnd the number b isnIs connected with one side of the half-wave plate (122), and the number b isnThe other surface of the half-wave plate (122) and the number gnIs connected to the second prism (152).
6. The laser speckle reduction device as claimed in claim 5, wherein the half-wave plate (122) is coated with antireflection films on the light inlet surface and the light outlet surface.
7. The laser speckle reduction device according to claim 5, wherein the number of the polarization state conversion mechanisms (120) is three, and three half-wave plates (122) in the three polarization state conversion mechanisms (120) correspond to red light, green light and blue light respectively.
8. A scanning projection device comprising the laser speckle reduction apparatus of any one of claims 1 to 7.
9. The scanning projection device of claim 8, wherein the scanning projection device comprises a scanning spot generator, the scanning spot generator comprises a plurality of light source mechanisms and a beam combining assembly (250), the beam combining assembly (250) is configured to combine the laser light output by the plurality of light source mechanisms;
the scanning light spot generator further comprises a shaping structure, and the shaping structure is used for shaping the oval light spots emitted by the light source mechanism into round light spots.
10. The scanning projection device of claim 9, wherein the shaping structure is located behind the beam combining assembly (250) for shaping the combined laser light.
11. A scanning projection device according to claim 9, wherein the number of said shaping structures is the same as the number of said light source mechanisms, and there is a one-to-one correspondence;
the shaping structure is positioned between the light source mechanism and the beam combining component (250) so that light emitted by the light source mechanism is shaped and then combined.
12. The scanning projection device of claim 9, wherein the shaping structure is a prism assembly (260) or a biconic lens (240).
13. A scanning projection device according to claim 9 wherein the scanning projection device includes laser wavelength temperature drift detection means for detecting the amount of drift of the laser wavelength emitted by each light source means.
14. The scanning projection device of claim 9, wherein the beam combining assembly (250) comprises a plurality of spaced beam combining sheets or a plurality of beam combining prisms connected to each other.
15. The scanning projection device of claim 8, wherein the scanning projection device comprises a beam expander (400) located behind the scanning galvanometer (300), the beam expander (400) being configured to increase a field angle of the projection.
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| CN201921320970.4U CN210488147U (en) | 2019-08-15 | 2019-08-15 | Laser speckle eliminating device and scanning projection equipment |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110376755A (en) * | 2019-08-15 | 2019-10-25 | 浙江水晶光电科技股份有限公司 | Disappear laser speckle device and scanning projection device |
| CN115166992A (en) * | 2022-07-28 | 2022-10-11 | 苏州龙马璞芯芯片科技有限公司 | Laser scanning display device and method for inhibiting speckle contrast and head-up display system |
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2019
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110376755A (en) * | 2019-08-15 | 2019-10-25 | 浙江水晶光电科技股份有限公司 | Disappear laser speckle device and scanning projection device |
| CN115166992A (en) * | 2022-07-28 | 2022-10-11 | 苏州龙马璞芯芯片科技有限公司 | Laser scanning display device and method for inhibiting speckle contrast and head-up display system |
| CN115166992B (en) * | 2022-07-28 | 2024-02-06 | 苏州龙马璞芯芯片科技有限公司 | Laser scanning display device and method for inhibiting speckle contrast and head-up display system |
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