阅读说明：本技术 光学系统及光学设备 (Optical system and optical apparatus ) 是由 谈顺毅 于 2021-08-31 设计创作，主要内容包括：本发明提供了一种光学系统及光学设备,包括：空间光调制器和光源；所述空间光调制器在未施加调制信号时,所述光源照射所述空间光调制器后输出的光在观测系统上形成具有预设宽度的光斑或光斑阵列；所述空间光调制器在施加调制信号后,所述光源照射所述空间光调制器后输出的被调制的光在观测系统上形成所需调制的像素点图像。本发明彻底避免了安全隐患,通过引入被动保护机制,在成像器件不工作或无法正常工作的情况下,经过光学系统的光束在观看者眼中或检测系统中将无法聚焦成单个亮点,而只有成像器件能够正常工作时,光束才能在人眼或检测系统中形成像素点,从而成像。(The present invention provides an optical system and an optical apparatus, including: a spatial light modulator and a light source; when the spatial light modulator does not apply a modulation signal, light output after the light source irradiates the spatial light modulator forms a light spot or a light spot array with a preset width on an observation system; after the spatial light modulator applies the modulation signal, modulated light output after the light source irradiates the spatial light modulator forms a pixel point image which needs to be modulated on an observation system. The invention thoroughly avoids potential safety hazard, and by introducing a passive protection mechanism, under the condition that the imaging device does not work or can not work normally, the light beam passing through the optical system can not be focused into a single bright point in eyes of a viewer or a detection system, and only when the imaging device can work normally, the light beam can form a pixel point in the eyes of the viewer or the detection system, thereby imaging.)

1. An optical system, comprising: a spatial light modulator and a light source;

when the spatial light modulator does not apply a modulation signal, light output after the light source irradiates the spatial light modulator forms a light spot or a light spot array with a preset width on an observation system;

after the spatial light modulator applies the modulation signal, the modulated light output after the light source irradiates the spatial light modulator forms an image with required modulation on an observation system.

2. The optical system of claim 1, wherein the spatial light modulator uses phase modulation.

3. The optical system of claim 1, wherein the light source comprises a laser.

4. The optical system of claim 1, further comprising a waveguide device, wherein the light output from the light source after illuminating the spatial light modulator is transmitted to the observation system through the waveguide device.

5. The optical system of claim 1, further comprising at least one of a lens, a mirror, a prism, a half mirror, a dichroic mirror, a polarizing plate, a glass slide, a filter, a diaphragm, a pancharacnam-Berry phase device, and a diffraction device.

6. The optical system of claim 1, further comprising an aperture, wherein when no modulation signal is applied, the light output from the spatial light modulator illuminated by the light source is focused at one or more points in the optical system, and the aperture is disposed at the one or more points and is made of an opaque or reflective material to absorb or reflect the light at the one or more points out of the imaging optical path.

7. The optical system of claim 1, wherein the light output by the spatial light modulator illuminated by the light source is non-parallel at an entrance pupil surface of the waveguide when no modulation signal is applied.

8. The optical system of claim 1, wherein when the modulation signal is applied, the light output by the spatial light modulator illuminated by the light source is modulated into a virtual or real image having a distance from the observation system, the distance being changeable by a different modulation signal.

9. The optical system of claim 1, wherein when the modulation signal is applied, the light output from the spatial light modulator illuminated by the light source is modulated into an image, and the same image comprises sub-images having different distances from the viewing system, wherein the different distances can be changed by different modulation signals.

10. The optical system of claim 1, further comprising a control system.

11. The optical system of claim 10, wherein the control system outputs the modulation signal to control the spatial light modulator to modulate light emitted by the light source and/or to synchronously control the output of the light source.

12. An optical device comprising an optical system according to any one of claims 1 to 11.

Technical Field

The present invention relates to the field of optics, and in particular, to an optical system and an optical apparatus.

Background

The laser, especially the semiconductor laser, has the advantages of high brightness, small numerical aperture, pure color and the like as a novel light source. But due to the small numerical aperture, the laser light easily converges into a single high brightness small spot. In display applications, especially wearable AR/VR applications, a single ultra-high brightness point may cause a safety hazard or fail a safety test, limiting the application of laser in this field.

Patent document CN104898285A discloses a device for obtaining light field uniformization laser, wherein a laser beam irradiates a first surface of a holographic diffuser, penetrates through the holographic diffuser, enters the MEMS deformable mirror, and enters the holographic diffuser from a second surface of the holographic diffuser after being reflected by the MEMS deformable mirror, thereby effectively realizing uniformization of a laser light field.

In the existing display application using a laser light source, active safety measures are often used, for example, a display system of the laser light source and an MEMS galvanometer is used, single-beam laser rapidly scans through the MEMS galvanometer to change an emergent angle, and energy is evenly distributed to a whole image in time to realize display. If the laser still works but the MEMS galvanometer is damaged, the system triggers a protection mechanism to quickly close the laser, and the retina damage caused by the fact that single-beam hard light enters the same position of the human eye for a long time is avoided. However, this method depends on the protection mechanism being able to work normally, and if the protection mechanism fails for some reason, a great potential safety hazard will be brought.

In the scheme of using laser holographic imaging, due to a Spatial Light Modulator (SLM), there is often a very bright 0-level bright spot (accounting for 5% to 90% of the total energy, depending on the specific device) in the middle of the image. In the prior art, the bright spots are usually shielded by a diaphragm (even the whole half image is shielded) to shield stray light and protect safety. However, this method also has safety risks, and if the shading diaphragm fails (for example, due to a collision causing a displacement or a shading material being broken down by strong light), safety problems still occur.

Disclosure of Invention

In view of the defects in the prior art, the present invention provides an optical system and an optical apparatus.

According to the present invention, there is provided an optical system comprising: a spatial light modulator and a light source;

when the spatial light modulator does not apply a modulation signal, light output after the light source irradiates the spatial light modulator forms a light spot or a light spot array with a preset width on an observation system; spots or lightThe preset size of the spot array may be such that the energy distribution per unit area meets safety regulations (e.g., safety regulations)<0.5mw/mm²)

After the spatial light modulator applies the modulation signal, the modulated light output after the light source irradiates the spatial light modulator forms an image with required modulation on an observation system. The observation system can be human eyes, and also can be electronic devices such as cameras, films or CCD (charge coupled device), CMOS (complementary metal oxide semiconductor) sensors and the like

Preferably, the spatial light modulator uses phase modulation. Such as liquid crystal on silicon (LCoS) or transmissive LCD using ECB or VA encapsulation, or LCoS using ferroelectric liquid crystals, or LC lenses.

Preferably, the light source comprises a laser.

Preferably, the optical system further includes a waveguide device, and light output after the light source irradiates the spatial light modulator is transmitted to the observation system through the waveguide device. The waveguide device can function as a combiner to combine external environment light with image light output by the spatial light modulator, thereby realizing the AR effect of see through

Preferably, the optical system further comprises at least one of a lens, a mirror, a prism, a half mirror, a dichroic mirror, a polarizer, a glass slide, a filter, a diaphragm, a Pancharatnam-Berry phase device (PBOE, which can make different polarization modulation characteristics in different regions of the device, and then make different treatments on light incident to different regions by polarization), a diffractive device (e.g., a grating, a microstructure device, etc.).

Preferably, the optical system further includes an aperture, when no modulation signal is applied, the light output by the light source after illuminating the spatial light modulator is focused into one or more points at a position in the optical system, the aperture is disposed at the position, and an opaque or reflective material is prepared (for example, by a coating process, photolithography by a semiconductor process, a plating process, a printing process, or the like) at the position of the one or more points, and the one or more points into which the light is focused are absorbed or reflected out of the imaging optical path.

Preferably, when no modulation signal is applied, the light output by the spatial light modulator irradiated by the light source is non-parallel light on the entrance pupil surface of the waveguide device. Since the waveguides are typically designed in parallel optical mode, they act as a combiner and a pupil expander. Parallel lights with different angles correspond to infinite field points, and the parallel lights with the same angle are focused on a retina by a crystalline lens to form a point after entering the human eye, so when the output light is non-parallel light at the waveguide entrance pupil (for example, the parallel lights are focused to form a point near the entrance pupil surface, and the position of the point is arranged on the distance which can not be focused by the human eye), the divergence angle of the light at the point is very large after entering the waveguide, the energy can be dispersed in a very large range after the pupil is expanded by the waveguide, and the human eye can not focus the light to form a point after the light exits from the waveguide, thereby avoiding potential safety hazard.

Preferably, when the modulation signal is applied, the light source illuminates the light output by the spatial light modulator modulated to form an image in the viewing system. Preferably, when a modulation signal is applied, the light output by the spatial light modulator illuminated by the light source is modulated into a virtual or real image having a distance from the observation system, the distance being changeable by a different modulation signal. For example, the previous frame of image is a virtual image 5 meters away from the human eye, and the next frame of image is adjusted to a virtual image 1 meter away from the human eye, so that the multiple frames of images can be perceived as the same frame of image by the observer by using the visual residual effect through rapid temporal iteration. Or, a holographic algorithm or a simulated complex wavefront may be used to modulate the effect that a plurality of sub-images (objects) with different distances exist in one frame of image at the same time.

Preferably, when the modulation signal is applied, the light output by the spatial light modulator illuminated by the light source is modulated into an image, the same image contains ion images having different distances from the observation system, and the different distances can be changed by different modulation signals.

Preferably, the optical system further comprises a control system.

Preferably, the control system outputs the modulation signal to control the spatial light modulator to modulate the light emitted by the light source and/or synchronously control the output of the light source. The control system also functions to synchronize the spatial light modulator with the light source, e.g., the light source contains RGB lasers with only one color laser output at a time, while the spatial light modulator is synchronized to display an image (hologram) of the corresponding color. The laser can also be controlled to output different powers at different moments according to the total brightness required by the corresponding hologram (the brightness of the hologram is directly related to the display content, and the output power of the light source needs to be controlled to ensure that the brightness of the images with different contents is the same), so that the brightness requirement is met.

According to the invention, an optical device is provided, comprising the optical system.

Compared with the prior art, the invention has the following beneficial effects:

the invention thoroughly avoids potential safety hazard, and by introducing a passive protection mechanism, namely, under the condition that an imaging device (generally an electronic device) does not work or cannot work normally, a light beam passing through an optical system cannot be focused into a single bright point (a light spot or an array with a certain size is formed in the eyes of a viewer or a detection system, so that energy is dispersed, and no safety risk exists), and only when the imaging device can work normally, the light beam can form a pixel point in the eyes of the viewer or the detection system, so that imaging is realized.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic diagram of one embodiment of the present invention, employing a reflective SLM;

FIG. 2 is a schematic diagram of one embodiment of the present invention, employing a reflective SLM and prism system;

FIG. 3 is a schematic diagram of an embodiment of the present invention, which uses a reflective SLM to implement a lens function through the SLM, simplifying the design of the optical system;

FIG. 4 is a schematic diagram of an embodiment of the present invention using a transmissive SLM.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

The present invention provides an optical system including: a spatial light modulator and a light source. When the spatial light modulator does not apply a modulation signal, light output after the spatial light modulator is irradiated by the light source forms a light spot or a light spot array with a preset width on the observation system. After the spatial light modulator applies the modulation signal, the modulated light output by the light source after illuminating the spatial light modulator forms an image with required modulation on the observation system. The spatial light modulator is controlled by the control system to output a modulation signal to modulate the light emitted by the light source.

When the modulation signal is applied, the light source illuminates the light output by the spatial light modulator and is modulated to form an image in the viewing system. Alternatively, the light source illuminates the light output by the spatial light modulator to be modulated as a virtual or real image at a distance from the viewing system, which can be changed by different modulation signals. When no modulation signal is applied, the light output by the spatial light modulator irradiated by the light source is non-parallel light on the entrance pupil surface of the waveguide device or light which cannot be focused on the observation system. The optical system further comprises at least one of a lens, a reflector, a prism, a half-transmitting and half-reflecting mirror, a dichroic mirror, a polarizing plate, a glass sheet, a filtering plate and a diaphragm. When no modulation signal is applied, the light output by the spatial light modulator after being irradiated by the light source is focused into one or more points at a certain position in the optical system, the diaphragm is arranged at the position, the light-proof or light-reflecting material is prepared at the position of the one or more points, the one or more points into which the light is converged are absorbed or reflected out of the imaging light path, and the light at the rest positions (the light outside the focus on the diaphragm) can continuously propagate through the diaphragm.

The viewing system may be a human eye comprising a lens, a pupil and a retina (or equivalent optics such as CCD, CMOS or a camera) on which the spots or images (pixels) are formed.

When no modulation signal is applied, the light output by the spatial light modulator after being irradiated by the light source is focused into one or more points at one position in the optical system, the diaphragm is arranged at the position, the light-proof or light-reflecting material is prepared at the position of the one or more points, and the one or more points formed by converging the light are absorbed or reflected out of the imaging light path. When no modulation signal is applied, the light output by the spatial light modulator irradiated by the light source is non-parallel light on the entrance pupil surface of the waveguide device.

When the modulation signal is applied, the light output from the light source illuminating the spatial light modulator is modulated into a virtual or real image having a distance from the observation system, which can be changed by different modulation signals. When the modulation signal is applied, the light output by the spatial light modulator irradiated by the light source is modulated into an image, the same image comprises sub-images with different distances from the observation system, and the different distances can be changed by different modulation signals.

Example 1

A wearable display system/device includes a spatial light modulator, a waveguide (grating waveguide or arrayed waveguide), a control system, and a lens system (as shown in fig. 1, the control system is not shown). The laser LD adopts an 80mw 520nm semiconductor laser, light beams are expanded into light beams which are approximately parallel light and have the diameter of about 10mm (50% from peak intensity) after being emitted from the laser through a beam expanding lens system and are irradiated on the SLM, the SLM is a reflective pure phase modulation spatial light modulator which is packaged by ECB or VA and based on silicon-based liquid crystal, the effective size of light modulation is about 12x7mm, the long edge is arranged at an incident beam by 45 degrees, and the effective aperture of the incident beam can cover the whole effective modulation area. When no modulation signal is applied or the SLM is not working properly, it acts like a plane mirror. The incident beam of nearly parallel light is reflected by the inoperative spatial light modulator and then input into a first lens/first group of lenses of an approximate 4f system, and is focused near the focal point f1, and a special diaphragm is arranged at the focusing position to shield the focused bright spot (0-level bright spot) of the beam. The diaphragm is made of transparent glass or plastic materials, light shielding materials (such as black paint or mirror-like materials capable of reflecting bright light) are prepared at the focal position, and the light shielding materials can be prepared at the periphery (outside an effective image area) of the diaphragm to shield other veiling glare. Thereafter, a second lens of the 4f system/second group of lenses is arranged, the back focal point of which is offset from the diaphragm position (non-standard 4f system) and is arranged such that an object point located at the diaphragm surface is focused on or near the entrance pupil surface of the subsequent waveguide after passing through the second lens (for example 20mm from the entrance pupil surface).

When the spatial light modulator cannot work normally, the bright light is shielded by the diaphragm. In extreme cases, the laser works normally, the spatial light modulator is damaged and cannot work normally, and meanwhile, the diaphragm is damaged or the position is shifted, so that a 0-level bright spot cannot be shielded, and at the moment, the second group of lenses focuses the bright spot on or near the entrance pupil surface of the waveguide again. The waveguide is designed by adopting a parallel light incidence model (parallel light at each angle is equivalent to a field point at infinity, enters the waveguide, is expanded for multiple times, is still parallel light after being output and is focused on a retina by human eyes for imaging), a 0-level bright spot on an entrance pupil surface is equivalent to different field points incident at each angle, light rays at a specific angle are transmitted by the waveguide and are also expanded for multiple times to exit, finally, the light rays are equivalent to a bright spot to form a series of light spots which cannot be focused by eyes of a viewer, energy is greatly dispersed, and accordingly damage of a single ultrahigh bright spot to the human eyes is avoided.

When the spatial light modulator works normally, the spatial light modulator simulates a light wave front transmitted to a spatial light modulation surface by a virtual object (image) at a certain distance in front of and behind the spatial light modulator, the object distance enables the light wave front to be focused to the vicinity of a back focus of a second lens/a second group of lenses (an intermediate image surface) after being transmitted to the first lens/the first group of lenses, the intermediate image surface becomes image light close to infinity (or at least has a certain distance from a waveguide entrance pupil, for example, beyond 1 meter) after being modulated by the second group of lenses, and then the image light is coupled into the waveguide entrance pupil, so that the image light can be correctly viewed by a viewer after being guided out of the waveguide. The modulation signal is generated by the control system and can be obtained by dynamically simulating the lens phase by using a spatial light modulator as described in chinese patent ZL201310431070.8 (the light field effect can be obtained by a correlation method, different frames of images are displayed at different distances, and different parts of the same frame of image are displayed at different distances). The image can be obtained by Fourier transform (equivalent infinite image), and the imaging quality can be improved by the method in Chinese patent ZL2010105976. X. The above calculation may also take into account the 45 ° setting of the spatial light modulator, and eliminate aberration caused by the 45 ° setting or other aberrations such as spherical aberration and coma existing in the optical system by phase compensation (for example, using zernike polynomial to simulate phase to compensate aberration, calculating optical path to obtain phase difference, and directly calculating the optical path difference caused by the above tilt). The modulation signal can be generated by real-time calculation, or a plurality of modulation signals generated in advance can be pre-stored in the control system and selectively output according to requirements when in use. The control system outputs the modulation signal to control the spatial light modulator to modulate the light emitted by the light source and/or synchronously control the output of the light source.

In the above embodiment, a Pancharatnam-Berry phase device (PBOE) may be further added, the linearly polarized light output by the spatial light modulator may be equivalently regarded as the superposition of two circular polarizations, and the PBOE device will produce different phase delays for the input left and right circularly polarized light, in other words, the PBOE device can separate the linear polarization positive light area into different left and right circularly polarized light to be modulated respectively. By arranging the PBOE device in the optical path (e.g. between the first and second sheet lenses) and designing the PBOE device (e.g. using a liquid crystal device, with different alignment directions of different regions), so that the left and right circularly polarized light in the above system is modulated respectively, the light in different regions on the surface can also be modulated respectively, thereby realizing the function of expanding a complete optical surface into a plurality of discrete optical surfaces (the total spatial bandwidth product/numerical aperture of the discrete light-transmitting surfaces is not changed, but the total area of the discrete surfaces combined with the non-light-transmitting surfaces sandwiched between the discrete surfaces is expanded). The benefit of doing so is that the display effect of a larger spatial bandwidth product/numerical aperture (larger FOV and/or out-tone size) can be approximated by multiple viewpoints (e.g., multiple Maxwellian views, multiple beamlets) in conjunction with the entire optical system. In the above embodiments, a glass plate, an optical rotation plate, a polarizer, etc. may be added to modulate the circular polarization and change it to another polarization state (e.g. to a linear polarization) for better coupling with the waveguide. The PBOE device can be replaced by a diffraction type device (such as a grating) to realize the same function, or the PBOE device can be combined with the diffraction type device to realize better effect.

The control system also synchronizes the outputs of the light source and the spatial light modulator, and controls the energy output by the light source according to the required brightness (which can be realized by TTL/PWM modulation or modulation of the output current intensity), and the required brightness can be obtained by comprehensively calculating parameters such as image content/total energy, expected image brightness (a light intensity sensor can be installed in the system to obtain the ambient light brightness, and the expected image brightness is calculated according to the ambient light brightness), and the like.

In the above embodiments, the stop position may also be located on the entrance pupil surface of the waveguide, and this design may be considered to use a convex-concave two-lens or two-group lens (similar to a galilean telescope) to shorten the optical path size, or to use only one lens or group of lenses to further reduce the volume.

In the above embodiment, the incident light may also be non-parallel light, and in combination with the arrangement of the subsequent lens 1, when the SLM is not in operation, the incident light is focused to the stop position.

In the above embodiment, the light source may be formed by combining colors by using a color laser (for example, using an X prism, a dichroic mirror, or an optical fiber), and when a color light source is used, the light of all colors may be focused at the same position by setting the position of the light source different from the beam expander, so as to be shielded by the diaphragm.

In the above embodiment, the stray light may be filtered by using an angle filtering method without a diaphragm, for example, by using a special prism, by designing the optical waveguide, the light at a specific angle cannot be coupled into the waveguide, and the like.

Example 2

In another embodiment (as shown in fig. 2), the optical path size can be reduced by a prism, the laser outputs linearly polarized light and passes through BS, and a portion of the light is reflected by BS to the polarizer and absorbed by the polarizer because the polarization direction is perpendicular to the polarization direction allowed to pass by the polarizer. And the other part of the light is transmitted to the curved surface reflector through the BS to modulate focal power, so that the light is focused near the focus of the first lens/first lens group, meanwhile, the back surface of the reflector is provided with a special reflective coating (such as a grating structure) which can enable the polarization direction of the incident linearly polarized light to rotate by 90 degrees after being transmitted, when the reflected light passes through the BS again, one part of the reflected light cannot enter an imaging light path through the BS, the other part of the reflected light is reflected to the first lens by the BS, and the reflected light is modulated to be approximate parallel light by the first lens and then is transmitted to the SLM to be modulated by the SLM. Then the SLM reflects the incident light to the first lens, the light enters the first lens again, is modulated by the first lens and then enters the BS, a part of the same light is reflected again to the curved mirror (since the polarization direction is changed again, most of the part of the light cannot enter the imaging optical path after being refracted and reflected for multiple times), another part of the same light enters the imaging optical path through the BS, and since the polarization direction has been rotated by 90 °, the light can pass through the polarizer.

When the SLM is not normally operated, quasi-parallel light incident to the SLM is reflected and focused on the polarizer by the first lens, the polarizer is coated with a shielding material at the position of the parallel light focus (0-level bright point), so as to shield light which is not modulated or modulated incorrectly by the SLM, if the polarizer/shielding sheet has a problem (such as position movement or damage of the shielding material) and cannot shield the 0-level bright point, the light is modulated by the second lens/second lens group to form a real image behind the eyes of a viewer (cannot be focused on the retina by human eye crystalline lens), so that only one large bright point can be formed on the retina, and the energy is prevented from being concentrated on a single damaged retina.

The SLM normally works to modulate light into an image equivalent to any position between 300mm and 2000mm behind the surface of the SLM, the position of the image can be adjusted by the SLM transformation modulation parameters, and after passing through the first lens, the light is focused to be near the focus of the second lens/second lens group (the back focus of the first lens is not coincident with the front focus of the second lens), so that the light is modulated into any image from infinity to 20cm in front of the human eye.

In the above embodiment, a larger EYEBOX can be realized by adding a waveguide (grating waveguide, array waveguide, etc.) as in embodiment 1.

In the above embodiment, the lasers with different wavelengths (for example, RGB three colors) may be combined by an X prism (or multiple pieces of 2-item chromatic mirrors, or optical fibers), so as to implement color display. When using color display, the distance of different lasers from the collimating mirror can be set to different values, so that the 0-order bright spots of different lasers can be focused on the polarizer/shutter together.

In a variation of this embodiment, as shown in fig. 3, a simplest system can be implemented, which only includes the BS/PBS for combining, the laser, the spatial light modulator, and the mask, and the function of the lens is completely implemented by the spatial light modulator through phase modulation.

As shown in fig. 4, in another embodiment, a transmissive spatial light modulator may be used instead of the reflective spatial light modulator, and the optical path is changed/simplified accordingly (for example, the light source transmits through the SLM, and a combiner such as BS/PBS is not needed), similar to the previous embodiment, the spatial light modulator simulation lens may make the spatial position of the intermediate image point when the SLM is normally working different from the spatial position where the light source is focused when the SLM is not working, and a shielding device is added in the system to shield the unmodulated 0-level bright spot, so that even if the shielding sheet and the spatial light modulator are damaged simultaneously, the unmodulated light cannot be focused into a single bright spot in the observation system (for example, human eye), and the risk of damage caused by the laser is fundamentally avoided.

In the above embodiment, BS may be replaced by PBS, and the spatial light modulator may be replaced by a device capable of changing the polarization direction of incident light while being phase-adjusted (for example, a binary phase-modulated spatial light modulator using ferroelectric liquid crystal, the input/output polarization direction being rotated by 90 °). At the moment, linearly polarized light emitted by the laser penetrates through the PBS to enter the curved surface reflector, the polarization direction is rotated by 90 degrees by the reflection film coated on the reflector and changing the polarization direction, then the linearly polarized light returns to the PBS, the linearly polarized light is reflected to the first lens (or the curved surface reflector is not available, and light emitted by the laser is directly reflected to the first lens), the linearly polarized light is modulated into quasi-parallel light by the first lens and then is input into the spatial light modulator, the polarization direction is rotated by 90 degrees after the phase modulation is carried out on the spatial light modulator, and the quasi-parallel light can penetrate through the BS to be emitted to an imaging light path after the re-modulation is carried out on the spatial light modulator. In this modification, the polarizing plate may be omitted and only the shielding sheet may be added. The principle of 0-level bright light shielding and preventing the light from entering human eyes is the same as that of the original embodiment. The advantage of this solution is that while reducing the system volume, there is no waste of light energy due to multiple simultaneous transmissions and reflections of part of the light by the BS.

The optical system of the present invention can be applied to optical devices such as display devices and the like.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.