CN113687518B - Optical system and optical apparatus - Google Patents
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0938—Using specific optical elements
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/0081—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means for altering, e.g. enlarging, the entrance or exit pupil
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
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Abstract
The invention provides an optical system and an optical device, comprising: a spatial light modulator and a light source; when the spatial light modulator is not applied with a modulation signal, the light output by the light source after irradiating 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 is applied with a modulation signal, the light source irradiates the modulated light output by the spatial light modulator to form a pixel point image required to be modulated on an observation system. The invention thoroughly avoids potential safety hazards, and by introducing a passive protection mechanism, under the condition that an imaging device does not work or cannot work normally, a light beam passing through an optical system cannot be focused into a single bright spot 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 eyes of a person or the detection system, so that imaging is realized.
Description
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 semiconductor laser, has the advantages of high brightness, small numerical aperture, pure color, etc. as a novel light source. But because of the small numerical aperture, the laser easily clusters into a single high brightness spot. In display applications, particularly wearable AR/VR applications, a single ultra-high brightness point may bring a potential safety hazard or fail a safety test, limiting the application of laser in this field.
Patent document CN104898285a discloses a device for obtaining a light field homogenized 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 again from a second surface of the holographic diffuser after being reflected by the MEMS deformable mirror, thereby effectively realizing homogenization of a laser light field.
In the existing display application using a laser light source, active safety measures, such as a display system of the laser light source and an MEMS vibrating mirror, are often used, and a single laser rapidly scans through the MEMS vibrating mirror to change the emergent angle, so that the energy is equally distributed on the whole image in time to realize display. If the laser still works but the MEMS galvanometer is damaged, the system can trigger a protection mechanism to rapidly turn off the laser, so that retinal damage caused by long-time entry of a single beam of strong light into the same position of human eyes is avoided. However, this method depends on that the protection mechanism can work normally, and if the protection mechanism fails for some reasons, a great potential safety hazard is brought.
In schemes using laser holographic imaging, there is often a very bright 0-order bright spot (5% -90% of the total energy, depending on the particular device) in the middle of the image due to the spatial light modulator (Spatial Light Modulator, SLM) itself. The existing method is to shield the bright spots (even shield the whole half image) through the diaphragm so as to shield the stray light and protect the safety. However, this method also has a safety hazard, and if the shielding diaphragm fails (for example, the shielding diaphragm is displaced due to collision or the shielding material is broken down by strong light), a safety problem still occurs.
Disclosure of Invention
In view of the drawbacks of the prior art, an object of the present invention is to provide an optical system and an optical device.
An optical system according to the present invention includes: a spatial light modulator and a light source;
when the spatial light modulator is not applied with a modulation signal, the light output by the light source after irradiating the spatial light modulator forms a light spot or a light spot array with a preset width on an observation system; the predetermined size of the spot or array of spots may be such that the energy distribution per unit area meets safety specifications (e.g<0.5mw/mm 2 )
After the spatial light modulator is applied with the modulation signal, the light source irradiates the modulated light output by the spatial light modulator to form a required modulated image on an observation system. The observation system can be human eyes, cameras, films or electronic devices such as CCD, CMOS sensors and the like
Preferably, the spatial light modulator uses phase modulation. Such as an ECB or VA packaged liquid crystal on silicon device (LCoS) or transmissive LCD, or an LCoS using ferroelectric liquid crystals, or LC lenses.
Preferably, the light source comprises a laser.
Preferably, the optical system further comprises a waveguide device, and the 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 act as a combiner to combine the external environment light with the image output by the spatial light modulator, thereby realizing the AR effect of seethrough
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 slide, a filter, a diaphragm, a Pancharatnam-Berry phase device (PBOE, which may be fabricated with different polarization modulation properties in different regions of the device, after which light incident to the different regions is treated differently by polarization), a diffractive device (e.g. a grating, a micro-structured device, etc.).
Preferably, the optical system further includes a diaphragm, and when the modulation signal is not 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, and the diaphragm is disposed at the position and is made of a light-proof or light-reflective material (such as a coating process, a photolithography process, a film plating process, a printing process, etc.) at the position of the one or more points, so that the one or more points formed by the light are absorbed or reflected out of the imaging light path.
Preferably, when no modulation signal is applied, the light output by the light source irradiating the spatial light modulator is non-parallel light on the entrance pupil surface of the waveguide device. Since waveguides are typically designed in parallel optical modes, they act as combiner and pupil expander. Parallel light with different angles corresponds to an infinite field point, and the parallel light with the same angle is focused on the retina by the lens to form a point after entering the human eye, so when the output light is non-parallel light at the entrance pupil of the waveguide (for example, the output light is focused to form a point near the entrance pupil surface, the position of the point is set at a distance which can not be focused by the human eye), the divergence angle of the light at the point after entering the waveguide is large, the energy after being expanded by the waveguide is dispersed to a large range, and the human eye can not focus the light to form a point after exiting the waveguide, thereby avoiding potential safety hazards.
Preferably, when the modulation signal is applied, the light output from the light source illuminating the spatial light modulator is modulated to form an image in the observation system. Preferably, when the modulation signal is applied, the light output by the light source illuminating the spatial light modulator is modulated into a virtual or real image having a distance from the observation system, which distance can be varied by different modulation signals. For example, the former frame of image is a virtual image 5 m away from the human eye, the latter frame of image is adjusted to be a virtual image 1 m away from the human eye, and the multi-frame image can be perceived as the same frame of image by an observer through rapid iteration in time by utilizing the vision residual effect. Alternatively, a hologram algorithm or a complex wavefront may be used to modulate the effect of sub-images (objects) having a plurality of different distances in one frame of image at the same time.
Preferably, when a modulation signal is applied, the light emitted by the light source and output by the spatial light modulator is modulated into an image, and the same image contains ion images with 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 controls 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 comprises RGB three-color lasers, with only one color laser output at a time, while the synchronized spatial light modulator displays the corresponding color image (hologram). The laser can be controlled to output different powers at different moments according to the total brightness (the brightness of the hologram is directly related to the display content, so as to ensure that the brightness of images with different contents is the same, and the output power of a light source needs to be controlled) required by the corresponding hologram, thereby meeting the brightness requirement.
According to the invention, an optical device comprises the optical system.
Compared with the prior art, the invention has the following beneficial effects:
the invention thoroughly avoids potential safety hazards, 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 spot (a spot or an array with a certain size so as to disperse energy and have no safety risk) in an eye 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 eye of the person or the detection system so as to image.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
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 one embodiment of the present invention employing a reflective SLM, through which lens functionality is achieved, simplifying the optical system design;
FIG. 4 is a schematic diagram of an embodiment of the present invention employing 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 present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
The present invention provides an optical system including: spatial light modulator and light source. When the spatial light modulator is not applied with a modulation signal, the light output by the light source after irradiating 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 is applied with the modulation signal, the light source irradiates the modulated light outputted from the spatial light modulator to form a desired modulated image on the observation system. The spatial light modulator is controlled by the control system output modulation signal to modulate the light emitted by the light source.
When the modulation signal is applied, the light output from the light source illuminating the spatial light modulator is modulated to form an image in the observation system. Alternatively, 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 viewing system, which can be varied by different modulation signals. When no modulation signal is applied, the light output by the light source irradiating the spatial light modulator 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 also comprises at least one of a lens, a reflector, a prism, a semi-transparent semi-reflective mirror, a dichroic mirror, a polaroid, a glass slide, a filter and a diaphragm. When no modulation signal is applied, the light output by the light source after irradiating the spatial light modulator is focused into one or more points at a certain position in the optical system, the diaphragm is arranged at the position, and opaque or reflective materials are prepared at the position of the one or more points, so that the one or more points formed by converging the light are absorbed or reflected out of an imaging light path, and the light (the light beyond the focus on the diaphragm) at the rest positions can continuously propagate through the diaphragm.
The viewing system may be a human eye comprising a lens, pupil and retina (either CCD, CMOS, etc. optics or camera, etc.) on which the light spots or images (pixels) are formed.
When no modulation signal is applied, the light output by the light source after irradiating the spatial light modulator is focused into one or more points at one position in the optical system, the diaphragm is arranged at the position, and a light-proof or light-reflecting material is prepared at the position of the one or more points, so that 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 from the light source irradiating the spatial light modulator is non-parallel light at 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 varied by different modulation signals. When the modulating signal is applied, the light output by the light source irradiating the spatial light modulator 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 modulating signals.
Example 1
A wearable display system/device includes a spatial light modulator, a waveguide (grating waveguide or array waveguide), a control system, and a lens system (as shown in fig. 1, control system not labeled). The laser LD adopts 80mw 5200 nm semiconductor laser, the beam is expanded into a beam with the diameter of about 10mm (50%from peak intensity) by a beam expander system after exiting from the laser, the beam is irradiated on the SLM, the SLM adopts an ECB or VA packaged reflective pure phase modulation spatial light modulator based on silicon-based liquid crystal, the effective light modulation size is about 12x7mm, the long side is arranged at 45 degrees on the incident beam, 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 flat mirror. The incident beam of nearly parallel light is reflected by the non-working spatial light modulator and then is input into a first lens/first group of lenses of an approximate 4f system, and is focused near a focal point f1 of the first lens/first group of lenses, a special diaphragm is arranged at a focusing position, and a bright point (0-level bright point) focused by the beam is shielded. The diaphragm is made of transparent glass or plastic, a shading material (such as black paint or a mirror-like material capable of reflecting light) is prepared at the focal position, and the shading material can be prepared at the periphery (outside the effective image area) of the diaphragm to shade other parasitic lights. A second lens of the 4f system/second set of lenses is then arranged, the back focus of which is offset from the stop position (non-standard 4f system) and arranged such that an object point located at the stop surface passes the second lens and is focused on or near the entrance pupil surface of the subsequent waveguide device (e.g. 20mm from the entrance pupil surface).
When the spatial light modulator is not working properly, the bright light will be masked by the diaphragm. In extreme cases, the laser is operating normally, the spatial light modulator is damaged and not operating normally, while the aperture is damaged or shifted in position, resulting in a 0 th order bright spot that cannot be obscured, and the second set of lenses will refocus this bright spot on or near the waveguide entrance pupil plane. The waveguide adopts a parallel light incidence model design (parallel light at each angle is equivalent to a field point at infinity, enters the waveguide and is subjected to pupil expansion for multiple times, is still parallel light after being output, is focused on retina by human eyes for imaging), 0-level bright spots on the entrance pupil surface are equivalent to different field points at each angle, and light rays at specific angles are transmitted through the waveguide and are subjected to pupil expansion for multiple times and are finally equivalent to a bright spot to become a series of light spots which cannot be focused by eyes of viewers, and energy is greatly dispersed, so that damage of a single ultra-high bright spot to human eyes is avoided.
When the spatial light modulator is operating normally it simulates the wavefront of a virtual object (image) travelling to the spatial light modulating surface at a distance in front of and behind the spatial light modulator, said object distance being such that said wavefront will be focused near the back focus of the second lens/second set of lenses (intermediate image plane) after travelling to the first lens/first set of lenses, said intermediate image plane will become image light approaching infinity (or at least at a distance from the waveguide entrance pupil, e.g. 1 meter) after being modulated by the second set of lenses, and will then couple into the waveguide entrance pupil, so that it can be correctly viewed by a viewer after waveguide exit. The modulation signal is generated by a control system and can be obtained by dynamically simulating the phase of a lens 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 frame images are displayed at different distances, and different parts of the same frame image are displayed at different distances). The image can be obtained through Fourier transformation (equivalent infinity image), and the imaging quality can be improved through a method in Chinese patent ZL 20101059595976. X. The above calculation may also take into account the 45 ° setting of the spatial light modulator, and eliminate the aberration caused by the 45 ° setting or other aberrations such as spherical aberration and coma aberration existing in the optical system by phase compensation (for example, zernike polynomial analog phase is used to compensate the aberrations, and then, for example, the optical path is calculated to obtain the phase difference, and the optical path difference caused by the above tilt is directly counted during calculation). The modulation signal can be generated by real-time calculation or can be a plurality of modulation signals generated in advance to be prestored in a control system, and the modulation signals can be selected and output according to the needs 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 panharatnam-Berry phase device (PBOE) may be further added, the linearly polarized light output by the spatial light modulator may be equivalently regarded as superposition of two circular polarizations, while the PBOE device will generate different phase delays for the input left and right circular polarized light, in other words, the linearly polarized light may be divided into different left and right circular polarized lights to be modulated respectively by the PBOE device. By arranging the PBOE device in the optical path (e.g. between the first and second lenses) and for the design of the PBOE device (e.g. using liquid crystal devices, the alignment directions of the different regions are different), so that the left and right circular polarized light in the above system are modulated separately, the light of the different regions on this surface can also be modulated separately, the function of expanding one complete optical surface into a plurality of discrete optical surfaces is achieved (the total spatial bandwidth product/numerical aperture of the discrete light-passing surfaces is unchanged, but the total area of the discrete surfaces in combination with the non-light-passing surfaces sandwiched between the discrete surfaces is expanded). This has the advantage that in combination with the whole optical system a larger spatial bandwidth product/numerical aperture display (larger FOV and/or out-of-order size) can be approximated by multiple viewpoints (e.g. multiple Maxwellian views, multiple beamlets). In the above embodiment, a glass slide, an optical rotation sheet, a polarizer and the like can be further added to modulate circular polarization, and change the circular polarization into other polarization states (for example, restore to linear polarization) so as to be coupled with the waveguide better. The PBOE devices described above may also be replaced with diffractive devices (e.g. gratings) to achieve the same function, or the PBOE in combination with diffractive devices achieve a better effect.
The control system also synchronizes the output 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 output current intensity), wherein the required brightness can be obtained by comprehensively calculating parameters such as the desired image brightness (a light intensity sensor can be arranged in the system to obtain the ambient light brightness and the desired image brightness is calculated according to the ambient light brightness) and the like according to the content/total energy of the image.
In the above embodiments, the aperture position may also be located on the waveguide entrance pupil surface, and with this design, it is considered to use two lenses (similar to galilean telescope) or two lens groups, one convex and one concave, so as to shorten the optical path size, or only one lens or lens group is used to further reduce the volume.
In the above embodiment, the incident light may also be non-parallel light, and in combination with the subsequent lens 1 arrangement, the incident light is focused to the stop position when the SLM is not in operation.
In the above embodiment, the light source may be formed by combining colors by using a color laser (for example, an X-prism, a dichroic mirror, or an optical fiber), and when using a color light source, light of all colors may be focused at the same position by setting different positions of the light source from the beam expander, so as to be shielded by the diaphragm.
In the above embodiment, no aperture may be provided, and stray light may be filtered by using an angle filtering method, for example, a special prism is used, and light with a specific angle cannot be coupled into the waveguide by the design of the optical waveguide.
Example 2
In another embodiment (as shown in fig. 2), the optical path size may be reduced by a prism, the laser outputs linearly polarized light and then passes through the BS, and a portion of the light is reflected by the BS to the polarizer, and the portion of the light is absorbed by the polarizer because the polarization direction is perpendicular to the polarization direction allowed by the polarizer. The other part of the light is transmitted through the BS and enters the curved reflector, the focal power is modulated to be focused near the focal point of the first lens/the 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 90 degrees after being transmitted, when the reflected light passes through the BS again, one part of the reflected light can not enter an imaging light path through the BS, and the other part of the reflected light is reflected to the first lens by the BS, is modulated into nearly parallel light by the first lens and then enters the SLM to be modulated by the SLM. The SLM then reflects the incident light to the first lens, the light re-enters the first lens, the light is modulated by the first lens and then enters the BS, the same part of the light is re-reflected to the curved mirror (most of the light cannot enter the imaging optical path after being subjected to multiple refraction and reflection due to the polarization direction being changed again), and the other part of the light enters the imaging optical path through the BS, and the light can pass through the polarizer this time due to the polarization direction being rotated by 90 °.
When the SLM is not working normally, the quasi-parallel light incident to the SLM will be focused on the polarizer by the first lens after being reflected, the polarizer is plated with shielding material at the position of the focus (0-level bright spot) of the parallel light, the light which is not modulated or modulated by the SLM will be shielded, if the polarizer/shielding sheet is out of order (e.g. the position is shifted or the shielding material is damaged) and the 0-level bright spot cannot be shielded, the light will be modulated by the second lens/second lens group to modulate the real image behind the eyes of the viewer (which cannot be focused on the retina by the human eye lens), thus only a larger spot can be formed on the retina, thereby avoiding the energy from concentrating on a single bright spot damaging the retina.
The SLM operates normally to modulate light to an image equivalent to an image anywhere between 300mm and 2000mm behind the SLM surface, the position of which can be adjusted by the SLM conversion modulation parameters, which light will be focused near the focal point of the second lens/second lens group after passing the first lens (the back focal point of the first lens does not coincide with the front focal point of the second lens) and thus modulated to an arbitrary image from infinity to 20cm in front of the human eye.
In the above embodiment, a waveguide (grating waveguide, array waveguide, etc.) may be added as in embodiment 1 to realize a larger EYEBOX.
In the above embodiment, the lasers with various different wavelengths (for example, RGB three colors) may be combined by an X-prism (or a plurality of 2-term color mirrors, or optical fibers), so as to realize color display. When using a color display, the distances of the different lasers from the collimator may be set to different values, so that the 0-order bright spots of the different lasers can be commonly focused on the polarizer/shielding plate.
As shown in fig. 3, in a modification of this embodiment, a simplest system can be realized, which includes only BS/PBS for combining, a laser, a spatial light modulator, and a masking sheet, and the function of the lens is completely realized by the spatial light modulator through phase modulation.
In another embodiment, as shown in fig. 4, a transmissive spatial light modulator may be used instead of a reflective spatial light modulator, and the optical path will be changed/simplified accordingly (e.g. the light source is transmitted through the SLM, without a BS/PBS combiner), which is the same as the previous embodiment, and the spatial position where the light source is focused when the SLM is not operating is different from the intermediate image point when the SLM is operating normally by the spatial light modulator analog lens, and a shielding device is added to the system to shield the non-modulated 0-level bright spots, even if the shielding sheet and the spatial light modulator are damaged at the same time, the non-modulated light will not be focused into a single bright spot in the observation system (e.g. human eye), so that 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 the incident light while modulating the phase (for example, a binary phase modulated spatial light modulator, which uses ferroelectric liquid crystal, and rotates the input/output polarization direction by 90 °). At this time, the linearly polarized light emitted by the laser enters the curved mirror through the PBS, the reflection film coated by the mirror and changing the polarization direction rotates 90 degrees to return to the PBS, the polarized light is reflected to the first lens (the curved mirror can be omitted, the light emitted by the laser is directly reflected to the first lens), the quasi-parallel light is modulated by the first lens and then enters the spatial light modulator, the polarization direction is rotated 90 degrees after the phase modulation is carried out by the spatial light modulator, and the polarized light can be emitted to an imaging light path through the BS after the polarization direction is modulated again by the first lens. In this modification, a polarizing plate may be omitted and only a masking plate may be added. The 0-level bright light shielding and prevention of entering the human eye are the same principle as in the original embodiment. The advantage of this solution is that it reduces the system volume and at the same time does not cause waste of light energy due to the BS transmitting and reflecting part of the light several times.
The optical system of the present invention can be applied to an optical device such as a display device or the like.
The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily without conflict.
Claims (11)
1. An optical system, comprising: a spatial light modulator and a light source;
when the spatial light modulator is not applied with a modulation signal, the light output by the light source after irradiating 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 is applied with a modulation signal, the light source irradiates the modulated light output by the spatial light modulator to form an image to be modulated on an observation system; the optical system further comprises a diaphragm, when no modulation signal is applied, the light output by the light source after irradiating the spatial light modulator is focused into one or more points at a position in the optical system, the diaphragm is arranged at the position, a light-tight 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 an imaging light path.
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 through which light output from the light source after illuminating the spatial light modulator is transmitted to the viewing system.
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 polarizer, a slide, a filter, a diaphragm, a Pancharactnam-Berry phase device, and a diffraction device.
6. The optical system of claim 4, wherein the light from the light source illuminating the output of the spatial light modulator is non-parallel light at an entrance pupil surface of the waveguide device when no modulation signal is applied.
7. An optical system according to claim 1, wherein the light from the light source illuminating the spatial light modulator output is modulated into a virtual or real image having a distance to the viewing system when a modulation signal is applied, the distance being changeable by a different modulation signal.
8. An optical system according to claim 1, wherein the light from the light source illuminating the spatial light modulator output is modulated into an image when a modulation signal is applied, the same image comprising sub-images having different distances from the viewing system, the different distances being changeable by different modulation signals.
9. The optical system of claim 1, further comprising a control system.
10. An optical system according to claim 9, 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.
11. An optical device comprising the optical system of any one of claims 1 to 10.
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