Optical system

Abstract

The invention provides an optical system, relates to the technical field of holography, and can improve the energy utilization rate of a light source. The optical system comprises a coherent light source, a beam splitting device and a first holographic plate. Wherein a light beam emitted by the coherent light source is split into a plurality of light beams through the beam splitting device, and the plurality of light beams comprise a first light beam and a second light beam. The first light beam and the second light beam are projected to the same imaging surface through the first light path and the second light path, the first holographic plate is arranged on the first light path where the first light beam is located, and the optical path difference between the first light beam and the second light beam is smaller than or equal to the coherent length of the coherent light source. According to the optical system, the zero-level light in the first light beam can be utilized by adopting a beam splitting mode, so that the energy utilization rate of the light source can be improved.

Description

Technical Field

[0001] The present application relates to the field of light shaping technology, and in particular to an optical system. Background Art

[0002] At present, optical holographic systems are widely studied in the field of optical display, which requires the light source to have high temporal and spatial coherence. Compared with traditional optical holographic technology, the present invention greatly reduces the requirements of the holographic system for the temporal coherence of the light source. At the same time, traditional optical holographic systems cannot use zero-order light during interference imaging, resulting in low energy utilization of the light source. Summary of the invention

[0003] The present application provides an optical system that utilizes 0-level light to improve the energy utilization rate of the light source.

[0004] The present application provides an optical system, which includes a coherent light source, a beam splitting device, and a first holographic plate. The light beam emitted by the coherent light source is split into multiple light beams by the beam splitting device, and the multiple light beams include a first light beam and a second light beam. The first light beam is projected onto the same imaging surface via a first optical path, and the second light beam is projected onto the same imaging surface via a second optical path. The first holographic plate is arranged on the first optical path where the first light beam is located, and the optical path difference between the first light beam and the second light beam is less than or equal to the coherence length of the two light beams. In this way, the 0th order light and the high-order light formed by the first light beam after passing through the first holographic plate are both projected onto the imaging surface, and are superimposed with the second light beam at the imaging surface to generate interference and diffraction to form a light pattern for holographic imaging; that is, when the optical system of the present application is used for imaging, the 0th order light in the first light beam can be utilized, thereby improving the energy utilization rate of the light source.

[0005] In some possible implementations, the beam splitting device is a wavefront splitting device.

[0006] In some possible implementations, the above-mentioned beam splitting device is an amplitude splitting device. In this case, two light beams with the same parameters (including phase and amplitude) can be obtained, thereby reducing the spatial coherence requirements for coherent light sources. Even when the spatiotemporal coherence of the light source is insufficient, high-contrast imaging can still be obtained.

[0007] In some possible implementations, the above-mentioned coherent light source includes at least one of a free electron laser source, a synchrotron radiation source, and a high-harmonic generation laser source.

[0008] In some possible implementations, the device further includes a second holographic plate, which is disposed on the second optical path. In this case, the 0th order light and the higher order light formed by the first light beam after passing through the first holographic plate, and the 0th order light and the higher order light formed by the second light beam after passing through the second holographic plate, are superimposed on the imaging surface to generate interference and diffraction to form an image; that is, the 0th order light of the first light beam and the 0th order light of the second light beam can both participate in interference imaging; in this way, the light beams are regulated by the two holographic plates together, thereby increasing the degree of freedom of light beam regulation, and thus reducing the difficulty of holographic plate processing and manufacturing.

[0009] In some possible implementations, a first hologram is recorded on the first holographic plate, and a second hologram is recorded on the second holographic plate. The first hologram and the second hologram are used to form a target pattern on an imaging plane.

[0010] In some possible implementations, the first holographic plate is a transmission holographic plate or a reflection holographic plate.

[0011] In some possible implementations, the second holographic plate is a transmission holographic plate or a reflection holographic plate.

[0012] In some possible implementations, at least one reflector is disposed on the first optical path to adjust the direction of the first light beam through the reflection effect of the reflector to ensure that the first light beam is projected onto the imaging surface.

[0013] In some possible implementations, at least one reflector is disposed on the second optical path to adjust the direction of the second light beam through the reflection effect of the reflector to ensure that the second light beam is projected onto the imaging surface.

[0014] In some possible implementations, the transmission holographic plate is one of an amplitude transmission holographic plate, a phase transmission holographic plate, and a complex amplitude transmission holographic plate.

[0015] In some possible implementations, the reflective holographic plate is one of an amplitude-type reflective holographic plate, a phase-type reflective holographic plate, and a complex-amplitude-type reflective holographic plate.

[0016] In some possible implementations, the reflective holographic plate is a curved plate; in this case, by adjusting the local and overall surface shapes of the holographic plate, a higher degree of freedom can be provided for light beam control.

[0017] In some possible implementations, the optical system may further include at least one of a monochromator, an aperture, a beam expander, a light homogenizer, a light detection device, a light measurement device, and a light positioning device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of an optical system provided in an embodiment of the present application;

[0019] Figure 2 A schematic diagram of the structure of an optical system provided in an embodiment of the present application;

[0020] Figure 3 A schematic diagram of the structure of an optical system provided in an embodiment of the present application;

[0021] Figure 4 A schematic diagram of the structure of an optical system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] The terms "first", "second", etc. in the embodiments of the specification of the present application, the claims, and the drawings are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order. "Connected", "connected", and similar words are used to express the intercommunication or interaction between different components, which may include direct connection or indirect connection through other components. "At least one (item)" refers to one or more, and "multiple" refers to two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, including a series of steps or units. Methods, systems, products, or devices are not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices. "Up", "down", "left", "right", etc. are only used relative to the orientation of the components in the drawings. These directional terms are relative concepts. They are used for relative description and clarification, and may change accordingly according to the change of the orientation of the components in the drawings.

[0024] For example, a holographic plate is an optical device that produces functional patterns on a substrate material such as a film, plastic, glass or holographic film. A holographic plate can also be referred to as a medium that records a hologram, which is a picture that uses a laser as a light source and uses a panoramic camera to record the subject on a high-resolution holographic film.

[0025] For example, the optical path difference refers to the difference in optical path lengths between two light beams, wherein the optical path length refers to the product of the geometric distance of light propagation and the refractive index of the medium on the distance length.

[0026] Exemplarily, the coherence length refers to the maximum optical path difference at which light sources with a certain spectral width can interfere.

[0027] Exemplarily, the wavefront division method and the amplitude division method are two methods for obtaining coherent light. The wavefront division method is to obtain coherent light by dividing the wavefront on the same wavefront. The amplitude division method obtains coherent light by dividing the amplitude (light intensity) of the same beam of light. The amplitude division method is to separate two beams of coherent light by reflection and transmission on the surface of a transparent medium.

[0028] In the present application, an optical device that uses the wavefront division method to obtain coherent light is called a wavefront division device, and an optical device that uses the amplitude division method to obtain coherent light is called an amplitude division device.

[0029] The following is a detailed description of the application scenarios of the optical system provided in the embodiments of the present application.

[0030] 1. Holographic projection

[0031] like Figure 1 As shown, the coherent light source 1 obtains a first light beam and a second light beam after passing through the beam splitter 2. The first light beam is projected onto the imaging surface 5 after passing through the holographic plate 3, and is superimposed with the second light beam at the imaging surface 5 to produce interference and diffraction, forming a light pattern for holographic imaging.

[0032] Exemplarily, the imaging formed by this scheme can also be used to produce holograms on substrate materials such as thin films, plastics, glass or holographic films.

[0033] Exemplarily, the optical system of the present application is used for holographic imaging and can be applied to display, for example, advertising display, presenting products, services and other content in the form of holographic projection, which can attract more attention and achieve better brand promotion effect; for example, landscape decoration, by synthesizing various images to increase interest.

[0034] 2. Holographic detection

[0035] The optical system provided in the present application is used to detect the reflective surface of a reflector.

[0036] Indicatively, for Figure 1 and Figure 3In the optical system shown in FIG. 1 , when the first holographic plate 31 is arranged on the first optical path L1 and the reflector is arranged on the second optical path L2 (without the holographic plate), the reflector 4 on the second optical path L2 can be used as the reflector to be detected, and the holographic image formed by the first light beam at the imaging surface 5 can be used as the reference image. The state of the reflective surface of the reflector to be detected can be inferred by using the reference image and the interference image formed by the first light beam and the second light beam at the imaging surface 5; that is, according to the interference image formed by the first light beam and the second light beam at the imaging surface 5 and the reference image formed by the first light beam at the imaging surface 5, the dimming performance detection of the reflective surface of the reflector to be detected can be realized.

[0037] The 0th order light does not participate in imaging. If it enters the human eye, it will be displayed as a white light spot on the holographic 3D image, which will eventually reduce the contrast and brightness of the holographic 3D image and affect the presentation effect of the holographic 3D image. It is usually necessary to filter out the 0th order light to eliminate the interference of the 0th order light on the final imaging effect. Compared with the holographic system in the prior art that does not utilize the diffraction of the 0th order light, resulting in low light energy utilization of the light source, the embodiment of the present application provides a holographic system, which divides the light emitted by the light source into multiple light beams so that the 0th order light (i.e., the main light) of the light beam can participate in the diffraction to realize holography, that is, the 0th order light of the light beam can be utilized, thereby improving the energy utilization of the light source.

[0038] The optical system provided in the embodiments of the present application is described in detail below.

[0039] Indicative, such as Figure 1 As shown, an embodiment of the present application provides an optical system, which includes a coherent light source 1, a beam splitting device 2, and a first holographic plate 31. The light beam emitted by the coherent light source 1 is split into multiple light beams by the beam splitting device 2, and the multiple light beams may include a first light beam and a second light beam; of course, a third light beam, a fourth light beam, etc. may also be included, and the present application does not limit this. The following embodiments are all described by taking two light beams as an example.

[0040] On this basis, if Figure 1As shown, the first light beam is projected onto the same imaging surface 5 (also referred to as the first imaging surface) via the first optical path L1, and the second light beam is projected onto the same imaging surface 5 (also referred to as the first imaging surface) via the second optical path L2, that is, it is divided into multiple light beams by the beam splitter 2 and projected onto the same position via different optical paths. The first holographic plate 31 is arranged on the optical path (i.e., the first optical path L1) where the first light beam is located, and the optical path difference between the first light beam and the second light beam is less than or equal to the coherence length of the coherent light source 1, and the coherence length in the present application may refer to the temporal coherence length of the light. In this way, the 0th order light and the higher order light (non-0th order light) formed by the first light beam after passing through the first holographic plate 31 are both projected onto the imaging surface 5, and are superimposed with the second light beam L2 at the imaging surface 5 to generate interference and diffraction to form a light pattern for holographic imaging; that is, the optical system of the present application can utilize the 0th order light in the first light beam, thereby improving the energy utilization rate of the light source.

[0041] In this embodiment, by adjusting the lengths of the paths of the first light beam and the second light beam to the imaging surface, the optical path difference between the first light beam and the second light beam can be adjusted. In addition, in order to ensure that the direction of the first light beam is adjusted to meet the requirements of the first light beam being projected onto the imaging surface 5, in some possible implementation methods, such as Figure 1 As shown, one or more reflectors 4 may be arranged on the first optical path L1 to adjust the direction of the first light beam through the reflection effect of the reflectors to ensure that the first light beam is projected onto the imaging surface 5 .

[0042] Similarly, in some possible implementations, such as Figure 1 As shown, one or more reflectors 4 may be arranged on the second optical path L2 to adjust the direction of the second light beam through the reflection effect of the reflectors to ensure that the second light beam is projected onto the imaging surface 5 .

[0043] On this basis, if Figure 2 As shown, in some possible implementations, a second holographic plate 32 may be further arranged on the second optical path L2. In this case, the 0th order light and the higher order light formed by the first light beam after passing through the first holographic plate 31, and the 0th order light and the higher order light formed by the second light beam after passing through the second holographic plate 32, are superimposed on the imaging surface 5 to generate interference and diffraction to form an image; that is, the 0th order light of the first light beam and the 0th order light of the second light beam can both participate in interference imaging; in this way, the light beams are regulated by the two holographic plates (31, 32), thereby increasing the degree of freedom of light beam regulation, and further reducing the difficulty of processing and manufacturing the holographic plates (31, 32).

[0044] In some possible implementations, a first hologram is recorded on the first holographic plate 31, and a second hologram is recorded on the second holographic plate 32. The first hologram and the second hologram are used to form a target pattern on the imaging surface. Exemplarily, the first hologram and the second hologram may be parts of the target pattern respectively; Exemplarily, the first hologram and the second hologram may be merged and form the target pattern.

[0045] The present application does not impose any limitation on the configuration of the coherent light source 1 , and a high-coherence light source or a low-coherence light source may be used, and the configuration may be made as required in practice.

[0046] Illustratively, in some possible implementations, the light source may include a free electron laser (FEL) light source, a synchrotron radiation light source, a discharge produced plasmas (DPP) light source, a high harmonic generation (HHG) light source, etc., and may also be other coherent light sources.

[0047] Among them, the free electron laser source is an important choice in the field of holography because of its high power, high efficiency, wide range tuning of wavelength and time structure of ultrashort pulses. For example, in some possible implementations, in the present application, the coherent light source 1 can use a free electron laser source, which can generate light with a wavelength of 1nm to 1μm.

[0048] In addition, the present application does not limit the specific configuration of the above-mentioned beam splitting device 2, and it can be configured as needed in practice.

[0049] For example, in some possible implementations, the beam splitting device 2 may be a wavefront splitting device. Schematically, the wavefront splitting device may include a wedge mirror, an edge reflector, and other beam splitting devices to split a single light beam emitted by the coherent light source 1 into multiple light beams. It can be understood that the wavefront splitting device utilizes the spatial dimensions of the light source to split the wavefront at different positions of the light source into two or more parts, and the phase difference of the separated wavefront as a new light source is determined by the spatial coherence of the original light source.

[0050] For another example, in some possible implementations, the above-mentioned beam splitting device 2 may be an amplitude splitting device. Schematically, the amplitude splitting device may be a beam splitting device including a grating, a self-supporting semi-transparent and semi-reflective structure, etc., to split a single light beam emitted by a coherent light source 1 into multiple light beams. Exemplarily, the amplitude splitting device separates two light beams by reflection and transmission at the same spatial position of the light source, and the light intensity of the two light beams after the separation is reduced (that is, the amplitude is divided), but the phase difference between the corresponding positions of the two light beams is completely fixed, that is, the two light beams have exactly the same optical parameters. The two light beams separated by reflection and transmission of the amplitude splitting device may be the first light beam and the second light beam, respectively.

[0051] That is to say, the phase stability between the multiple light beams split by the wavefront splitting device depends on the spatial coherence of the light source; while the two light beams split by the amplitude splitting device do not depend on the spatial coherence of the light source, and the two split light beams have exactly the same optical parameters (including phase and amplitude), and the phase difference is always fixed, so that a stable interference pattern can be determined on the imaging plane.

[0052] Therefore, compared to the prior art in which high-contrast imaging cannot be obtained due to insufficient spatial coherence of the light source, in the present application, when the beam splitting device 2 adopts an amplitude splitting device, two light beams with the same parameters can be obtained, thereby reducing the spatial coherence requirements for the coherent light source. Even when the spatial coherence of the light source is insufficient, high-contrast imaging can still be obtained.

[0053] As shown, due to the high coherence requirements of existing optical systems for light sources, it is difficult for some current light sources in certain wavelength bands to meet the coherence requirements. In contrast, the optical system provided in the embodiment of the present application reduces the coherence requirements for the light source by adopting an amplitude division device, so that the coherence of current light sources (such as FEL light sources, synchrotron radiation light sources, etc.) can well meet the requirements of holographic imaging.

[0054] Of course, in some possible implementations, in order to achieve modulation of the light beam emitted by the coherent light source 1, the device may also be provided with one or more optical devices including a monochromator, an aperture, a beam expander 6, a light homogenizing device, etc. Figure 4 As shown, the beam expander 6 can be arranged after the coherent light source 1 and before the beam splitter 2. Exemplarily, the positions of the monochromator, the aperture, and the light homogenizer can be the same as the beam expander 6, and can be arranged after the coherent light source 1 and before the beam splitter 2.

[0055] For example, in some embodiments, when the beam splitting device adopts a wavefront splitting device, in order to improve the coherence of the light beam, the spatial coherence of the light beam can be improved by setting an aperture.

[0056] For example, in some embodiments, a beam expansion device or a light homogenizing device may be used to achieve light beam shaping, and a light detection device, a light measuring device, or a light calibration device may be used to achieve light beam detection, measurement, and calibration.

[0057] In addition, the present application does not limit the configuration of the first holographic plate 31. In practice, a suitable holographic plate can be selected according to needs. For example, in some possible implementations, the first holographic plate 31 can be a transmission holographic plate. For another example, in some possible implementations, the first holographic plate 31 can be a reflection holographic plate.

[0058] Similarly, as for the configuration of the second holographic plate 32, the second holographic plate 32 can be a transmission holographic plate or a reflection holographic plate.

[0059] It should be understood that, for a holographic plate, an optical adjustment layer is provided on part of its surface to adjust parameters of incident light at different positions, such as phase, amplitude, etc., so that light at different positions can produce designed diffraction to generate a desired light pattern.

[0060] In the example, the transmission holographic plate can be any one of an amplitude transmission holographic plate, a phase transmission holographic plate, and a complex amplitude transmission holographic plate. The present application does not limit the specific configuration of the amplitude transmission holographic plate, the phase transmission holographic plate, and the complex amplitude transmission holographic plate, and they can be configured as needed in practice.

[0061] In an illustrative manner, the above-mentioned reflective holographic plate can be any one of an amplitude reflective holographic plate, a phase reflective holographic plate, and a complex amplitude reflective holographic plate. The present application does not limit the specific setting method of the amplitude reflective holographic plate, the phase reflective holographic plate, and the complex amplitude reflective holographic plate, and they can be set according to actual needs.

[0062] It is understandable that, when the holographic plates (such as 31, 32) are reflective holographic plates, the degree of freedom modulation can be improved by adjusting the local and overall surface shapes of the holographic plates. Therefore, in some possible implementations, in the optical system provided in the embodiment of the present application, one or both of the first holographic plate 31 and the second holographic plate 32 can be provided with reflective holographic plates with curved surfaces, thereby providing a higher degree of freedom for light beam control.

[0063] The present application does not limit the specific arrangement of the holographic plates and the reflectors on the first optical path L1 and the second optical path L2.

[0064] For example, in some possible implementations, Figure 1As shown, in some optical systems, a first reflector a and a first holographic plate 31 are provided on the first optical path L1, and the first holographic plate 31 is a transmission holographic plate. A second reflector b is provided on the second optical path L2. In this case, the light emitted by the coherent light source 1 is divided into a first light beam and a second light beam by the beam splitter 2. The first light beam is reflected by the first reflector a along the first optical path L1 and then projected to the imaging surface 5 through the first holographic plate 31; the second light beam is reflected by the second reflector b along the second optical path L2 to the imaging surface 5 and overlaps with the first light beam to form an image.

[0065] For example, in some possible implementations, Figure 2 As shown, in some optical systems, a first reflector a and a first holographic plate 31 are provided on the first optical path L1, and the first holographic plate 31 is a transmission holographic plate. A second reflector b and a second holographic plate 32 are provided on the second optical path L2, and the second holographic plate 32 is a transmission holographic plate. In this case, the light emitted by the coherent light source 1 is divided into a first light beam and a second light beam by the beam splitter 2. The first light beam is reflected by the first reflector a along the first optical path L1, and then projected to the imaging surface 5 through the first holographic plate 31; the second light beam is reflected by the second reflector b along the second optical path L2, and then projected to the imaging surface 5 through the second holographic plate 32 to overlap with the first light beam.

[0066] For example, in some possible implementations, Figure 3 As shown, in some optical systems, a first holographic plate 31 is provided on the first optical path L1, and the first holographic plate 31 is a reflective holographic plate. A first reflector a is provided on the second optical path L2. In this case, the light emitted by the coherent light source 1 is divided into a first light beam and a second light beam by the beam splitter 2. The first light beam is reflected along the first optical path L1 by the first holographic plate 31 to the imaging surface 5; the second light beam is reflected along the second optical path L2 by the second reflector b to the imaging surface 5 to overlap with the first light beam to form an image.

[0067] For another example, in some possible implementations, in some optical systems, a first holographic plate 31 is provided on the first optical path L1, and the first holographic plate 31 is a reflective holographic plate; a first reflector a and a second holographic plate 31 are provided on the second optical path L2, and the second holographic plate 31 is a transmissive holographic plate. In this case, the light emitted by the coherent light source 1 is divided into a first light beam and a second light beam by the beam splitting device 2, and the first light beam is reflected along the first optical path L1 by the first holographic plate 31 to the imaging surface 5; the second light beam is reflected along the second optical path L2 by the second reflector b, and is projected to the imaging surface 5 through the second holographic plate 31 to overlap with the first light beam to form an image.

[0068] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An optical system, characterized in that: The invention comprises a coherent light source, a beam splitting device and a first holographic plate. The light beam emitted by the coherent light source is split into a plurality of light beams by the beam splitting device. The plurality of light beams include a first light beam and a second light beam. The first light beam is projected onto the same imaging surface via a first optical path and the second light beam is projected onto the same imaging surface via a second optical path. The first holographic plate is arranged on the first optical path. The optical path difference between the first light beam and the second light beam is less than or equal to the coherence length of the coherent light source.

2. The optical system according to claim 1, characterized in that The beam splitting device is an amplitude splitting device or a wavefront splitting device.

3. The optical system according to claim 1 or 2, characterized in that: The coherent light source includes at least one of a free electron laser source, a synchrotron radiation source, and a high-harmonic generation laser source.

4. The optical system according to any one of claims 1 to 3, characterized in that: The optical system further includes a second holographic plate, and the second holographic plate is arranged on the second optical path.

5. The optical system according to claim 4, characterized in that A first hologram is recorded on the first holographic plate, and a second hologram is recorded on the second holographic plate. The first hologram and the second hologram are used to form a target pattern on the imaging plane.

6. The optical system according to any one of claims 1 to 5, characterized in that: The first holographic plate and / or the second holographic plate is a transmission holographic plate or a reflection holographic plate.

7. The optical system according to any one of claims 1 to 6, characterized in that: At least one reflector is arranged on the first optical path.

8. The optical system according to any one of claims 1 to 7, characterized in that: At least one reflector is arranged on the second optical path.

9. The optical system according to claim 5 or 6, characterized in that: The transmission holographic plate is one of an amplitude transmission holographic plate, a phase transmission holographic plate, and a complex amplitude transmission holographic plate; the reflection holographic plate is one of an amplitude reflection holographic plate, a phase reflection holographic plate, and a complex amplitude reflection holographic plate.

10. The optical system according to claim 5 or 6, characterized in that: The reflective holographic plate is a curved plate.

11. The optical system according to any one of claims 1 to 10, characterized in that: It includes one or more of a monochromator, an aperture, a beam expander, a light homogenizer, a light detection device, a light measuring device, and a light positioning device.

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