WO2023197310A1

WO2023197310A1 - Measurement system and method

Info

Publication number: WO2023197310A1
Application number: PCT/CN2022/087150
Authority: WO
Inventors: 陈兴宇; 周鹏程
Original assignee: 华为技术有限公司
Priority date: 2022-04-15
Filing date: 2022-04-15
Publication date: 2023-10-19

Abstract

The present application discloses a measurement system and method. The system comprises a first light splitting element, a first measurement device, a linear array photoelectric receiving device and an interference element. In the measurement system, a first beam of light from an optical element is divided into first transmitted light and first reflected light by the first light splitting element; then the first measurement device can measure the light intensity change value of the first reflected light, the light intensity change value of the first reflected light being used for representing the diffraction efficiency of the optical element; the interference element can receive the first transmitted light, and obtain and project interference fringes; then the linear array photoelectric receiving device can obtain image information of the interference fringes, the image information being used for representing the refractive index change amount of the optical element. Thus, the diffraction efficiency and the refractive index change amount of the optical element are measured, and then the performance of the optical element can be evaluated, thereby facilitating improvement of the process of the optical element.

Description

A detection system and method

Technical field

The present application relates to the field of optical technology, and in particular to a detection system and method.

Background technique

With the rapid development of modern optical and optoelectronic technology, optoelectronic instruments and their components have undergone profound and tremendous changes. Optical components are no longer just refractive lenses, prisms and mirrors. New optical elements such as microlens arrays, diffractive optical elements and gradient refractive index lenses are also increasingly used in various optoelectronic instruments, making optoelectronic instruments and their components more miniaturized, arrayed and integrated.

Among them, the principle of some optical elements (for example, holographic optical elements (HOE)) is based on the interference and diffraction of light waves, so the performance of these optical elements can be evaluated through parameters such as diffraction efficiency and refractive index change.

In summary, it can be seen that how to measure the diffraction efficiency and refractive index change of optical elements to evaluate the performance of optical elements and thereby improve the process of optical elements is an urgent technical problem in this field that needs to be solved.

Contents of the invention

The present application provides a detection system and method for measuring the diffraction efficiency and refractive index change of optical elements, thereby evaluating the performance of the optical elements and helping to improve the process of the optical elements.

In a first aspect, embodiments of the present application provide a detection system, which includes a first spectroscopic element, a first detection device, a linear array photoelectric receiving device, and an interference element. Wherein, the first spectroscopic element can be used to divide the first beam of light from the optical element into the first transmitted light and the first reflected light; the first detection device can be used to detect the light intensity change value of the first reflected light, and the first The light intensity change value of the reflected light is used to characterize the diffraction efficiency of the optical element; the interference element can be used to receive the first transmitted light, and obtain and project the interference fringes; the linear array photoelectric receiving device can be used to obtain the image information of the interference fringes, and the image information Used to characterize the refractive index change of optical components.

It should be noted that "projecting interference fringes" can be understood as projecting interference fringes on the receiving screen, and "the light intensity change value of the first reflected light is used to characterize the diffraction efficiency of the optical element" can be understood as the light intensity of the first reflected light. The strong change value is used to determine the diffraction efficiency of the optical element. "The image information is used to characterize the refractive index change of the optical element" can be understood to mean that the image information is used to determine the refractive index change of the optical element.

Based on the above detection system, the first beam of light from the optical element is divided into the first transmitted light and the first reflected light through the first spectroscopic element; then the first detection device can detect the light intensity change value of the first reflected light, and the first detection device can detect the change value of the light intensity of the first reflected light. The intensity change value of a reflected light is used to characterize the diffraction efficiency of an optical element; the interference element can receive the first transmitted light, obtain interference fringes, and project the interference fringes, and then the linear array photoelectric receiving device can obtain the image information of the interference fringes. The image information is used to characterize the refractive index change of the optical element. In this way, the diffraction efficiency and refractive index change of the optical element can be detected, and the performance of the optical element can be evaluated, which helps to improve the process of the optical element.

In a possible design, the above-mentioned optical elements are holographic optical elements (HOE), and accordingly, the above-mentioned first beam of light is holographic light. In this design, the holographic light from the holographic optical element can be split, and the diffraction efficiency and refractive index change of the holographic optical element can be measured, so that the performance of the HOE can be evaluated.

In a possible design, the above system may also include a first light source, a polarizing beam splitting element, a first shutter, a second shutter and a control device; wherein the first light source may be used to output a second beam of light; the polarizing beam splitting element may It is used to split the second beam of light to obtain the third beam of light and the fourth beam of light when the first shutter is opened; the control device can be used to control the opening of the second shutter to make the third beam of light and the fourth beam of light When the second shutter is opened, the HOE is incident and the HOE is exposed. In this design, after the second beam of light output from the first light source is split by the polarization splitting element, the second shutter is controlled to open, so that the third beam of light and the fourth beam of light obtained after the splitting are incident when the second shutter is opened. Go to HOE and expose HOE. In this way, by controlling the first shutter and the second shutter, the exposure control of the HOE can be realized, effectively simplifying the exposure light path of the HOE, and making the HOE's exposure light path simple to implement.

In a possible design, the control device can also be used to control the second shutter to close according to a preset period. When the second shutter is closed, the third beam of light irradiates the HOE to obtain holographic light. In this design, the control device controls the second shutter to close according to a preset period, so that the third beam of light illuminates the HOE when the second shutter closes, and holographic light can be obtained. In this way, there is no need to add a new optical path to generate holographic light, which further effectively simplifies the HOE's exposure optical path, making the HOE's exposure optical path small in size and simple to implement.

In a possible design, the above system may also include a second light source and a third shutter. Wherein, the second light source can be used to output the seventh beam of light; the control device can also be used to control the opening of the third shutter. When the third shutter is opened, the seventh beam of light irradiates the HOE to obtain holographic light; wherein, the seventh beam of light can be used to output the seventh beam of light. The beam propagates in the same direction as the third beam. In this design, a second light source and a third shutter are set up, that is, a new light path is added to generate holographic light, so that the third shutter is controlled to open through the control device, so that the seventh beam of light generated by the second light source is in the third shutter When turned on, the HOE is irradiated to obtain holographic light. In this way, the control device controls the second shutter relatively simply.

In a possible design, the above system further includes a second beam splitting element, a first beam expanding element, and a second beam expanding element; the first beam expanding element can be used to expand the third beam of light to obtain an expanded beam. the third beam of light; the second beam splitting element can be used to split the fourth beam of light to obtain the fifth beam of light and the sixth beam of light; the second beam expanding element can be used to expand the fifth beam of light, The fifth beam of light after beam expansion is obtained. Correspondingly, the above-mentioned third beam of light and the fourth beam of light are incident on the HOE when the second shutter is opened, and the HOE is exposed, including: the expanded third beam of light and the expanded fifth beam of light in the second When the shutter is opened, the HOE is incident and the HOE is exposed. In this design, the third beam is expanded through the first beam expanding element, and the fourth beam is split through the second beam splitting element to obtain the fifth beam, and the fifth beam is obtained through the second beam expanding element. Perform beam expansion, and then control the expanded third beam of light and the expanded fifth beam of light to be incident on the HOE when the second shutter is opened, thereby achieving exposure of the HOE. In this way, the exposure effect of HOE is better, which helps to improve the exposure process of HOE.

In a possible design, the above system further includes a second detection device; the control device is used to control the opening of the second shutter, so that the third beam of light and the fourth beam of light are incident on the HOE when the second shutter is opened. When the HOE is exposed, it is specifically used to: receive the first information from the second detection device, the first information indicates that the light intensity change value of the sixth beam of light is within the preset range; control the second shutter to open so that the expansion The third beam of light after the beam and the fifth beam of light after the beam expansion are incident on the HOE when the second shutter is opened, and the HOE is exposed. It can be understood that "the change value of the light intensity of the sixth beam of light is within the preset range" means that the second beam of light output by the first light source is stable, and then the third beam of light and the fourth beam of light obtained by splitting the second beam are The beams are also stable, that is, the two beams used to expose the HOE are stable. Therefore, in this design, the control device controls the HOE to start exposure only after determining that the two beams used to expose the HOE are stable, making the HOE exposure process more stable and helping to improve the accuracy of the HOE performance evaluation. .

In a possible design, the second detection device can be used to detect whether the change value of the light intensity of the sixth beam of light is within a preset range. When the change value of the light intensity of the sixth beam of light is within the preset range, Send first information to the control device. In this design, the stability of the second beam of light output by the first light source can be determined by detecting the change in light intensity of the sixth beam of light through the second detection device, thereby facilitating the control device to control the exposure process of the HOE.

In a possible design, the control device can also be used to: when the diffraction efficiency reaches a first threshold, and/or when the first parameter of the interference fringe reaches a second threshold, control the first shutter to close; wherein, One parameter includes width, shape, or brightness contrast. In this design, the control device combines the diffraction efficiency of the HOE and/or the first parameter of the interference fringe to control the exposure process of the HOE, so that the exposure control of the HOE meets the user's experimental needs.

In a possible design, when the third beam of light and the fourth beam of light expose the HOE, the third beam of light and the fourth beam of light may be incident on different sides of the HOE, or the third beam of light and the fourth beam of light may be incident on different sides of the HOE. The beam can be incident on the same side of the HOE. It should be noted that in the embodiment of the present application, the third beam of light and the fourth beam of light can be incident on different sides of the HOE, that is, a reflective exposure light path is formed; the third beam of light and the fourth beam of light can be incident on the HOE On the same side, a transmission exposure light path is formed. In this design, the transmissive exposure light path and the reflective exposure light path of the HOE are provided, so that the exposure light path provided by the embodiment of the present application can be flexibly implemented.

In a possible design, the first beam expansion element or the second beam expansion element includes a spatial light filter and a lens.

In a possible design, the first beam expansion element or the second beam expansion element includes a lens and an off-axis mirror.

In one possible design, the linear array photoelectric receiving device is a charge coupled device (CCD) camera or a complementary metal oxide semiconductor (CMOS) camera.

In a second aspect, embodiments of the present application provide a detection method, which method includes: a first spectroscopic element divides a first beam of light from an optical element into a first transmitted light and a first reflected light; a first detection device detects The light intensity change value of the first reflected light is used to characterize the diffraction efficiency of the optical element; the interference element receives the first transmitted light, obtains and projects the interference fringes; linear The array photoelectric receiving device acquires image information of the interference fringes, and the image information is used to characterize the refractive index change of the optical element.

In a possible design, the optical element is a holographic optical element HOE, and the first beam of light is holographic light.

In a possible design, the method further includes: when the first shutter is opened, the polarizing light splitting element splits the second beam of light to obtain a third beam of light and a fourth beam of light; wherein, the second beam The light is output by the first light source; the control device controls the opening of the second shutter so that the third beam of light and the fourth beam of light are incident on the HOE when the second shutter is opened, and the HOE is exposure.

In a possible design, the method further includes: the control device controls the second shutter to close according to a preset cycle, and when the second shutter closes, the third beam of light illuminates the HOE, The holographic light is obtained.

In a possible design, the method further includes: a control device controlling the opening of the third shutter so that the seventh beam of light irradiates the HOE when the third shutter is opened to obtain the holographic light. ; Wherein, the seventh beam of light is output by the second light source, and the propagation direction of the seventh beam of light and the third beam of light is the same.

In a possible design, the method further includes: a first beam expanding element expanding the third beam of light to obtain an expanded third beam of light; and a second beam splitting element expanding the fourth beam of light. The light is split to obtain a fifth beam of light and a sixth beam of light; the second beam expansion element expands the fifth beam of light to obtain an expanded fifth beam of light; the third beam of light and The fourth beam of light is incident on the HOE when the second shutter is opened, and the HOE is exposed, including: the expanded third beam of light and the expanded fifth beam of light. When the second shutter is opened, it is incident on the HOE, and the HOE is exposed.

In a possible design, the control device controls the opening of the second shutter so that the third beam of light and the fourth beam of light are incident on the HOE when the second shutter is opened, and the The HOE performs exposure, including: the control device receives first information from the second detection device, the first information indicating that the light intensity change value of the sixth beam of light is within a preset range; the control device controls the The second shutter is opened, so that the expanded third beam of light and the expanded fifth beam of light are incident on the HOE when the second shutter is opened, and the HOE is exposed.

In a possible design, before the control device controls the opening of the second shutter, the method further includes: the second detection device detects whether the change value of the light intensity of the sixth beam of light is within the preset range. Inside;

The second detection device sends the first information to the control device when the light intensity change value of the sixth beam of light is within the preset range.

In a possible design, the method further includes: the control device controlling the control device when the diffraction efficiency reaches a first threshold, and/or when the first parameter of the interference fringe reaches a second threshold. The first shutter is closed; wherein the first parameter includes width, shape or brightness contrast.

For the beneficial effects of the method described in the above second aspect and any optional design of the second aspect, please refer to the relevant description in the first aspect, and will not be described again here.

Description of the drawings

Figure 1A is one of the principle schematic diagrams of HOE applicable to the embodiment of the present application;

Figure 1B is the second schematic diagram of the principle of HOE applicable to the embodiment of the present application;

Figure 2 is a schematic structural diagram of an exposure light path;

Figure 3 is a possible structural schematic diagram of the detection system provided by the embodiment of the present application;

Figure 4 is another possible structural schematic diagram of the detection system provided by the embodiment of the present application;

Figure 5 is another possible structural schematic diagram of the detection system provided by the embodiment of the present application;

Figure 6 is another possible structural schematic diagram of the detection system provided by the embodiment of the present application;

Figure 7 is another possible structural schematic diagram of the detection system provided by the embodiment of the present application;

Figure 8 is another possible structural schematic diagram of the detection system provided by the embodiment of the present application;

Figure 9 is a schematic diagram of changes in the diffraction efficiency of HOE provided by the embodiment of the present application;

Figure 10 is a schematic diagram of the interference fringes of HOE provided by the embodiment of the present application;

Figure 11 is a schematic flow chart of HOE exposure control provided by an embodiment of the present application;

Figure 12 is a schematic flow chart of the detection method provided by the embodiment of the present application.

Detailed ways

The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

First, some terms used in this application will be explained. It should be noted that these explanations are for the convenience of understanding by those skilled in the art and do not limit the scope of protection claimed by this application.

1. Object light.

Object light is a beam emitted by a coherent light source, and the amplitude information and phase information corresponding to this beam need to be recorded through holographic optical elements.

2. Reference light.

The reference light is a beam of light that is coherent with the object light. The corresponding phases and amplitudes of the reference light and the object light can be the same. Optionally, in some embodiments, the reference light may be beam-expanded and then incident on the holographic element.

3. Reproduce light.

The reproduced light is a light beam used to reproduce the amplitude information and phase information of the object light. In some possible embodiments, the reproduced light may be reference light. In other possible embodiments, the reproduced light is generated by a newly added light source.

4. Holographic light.

Holographic light is a light beam with the same phase and amplitude as the object light obtained by illuminating holographic optical elements (HOE) with reproduced light.

Furthermore, for ease of understanding, the exposure principle of HOE is introduced below.

Currently, HOE exposure methods include transmission and reflection.

As shown in Figure 1A, in the transmission exposure method, the object light and the reference light are illuminated from the same side of the HOE according to the preset angle Δθ, the HOE is exposed, and the phase information and amplitude information of the object light are recorded into the In the HOE material; the reference light is then used as the reproduced light to illuminate the HOE alone along the exposure direction, and its transmitted light will propagate in the propagation direction of the object light to form holographic light.

As shown in Figure 1B, in the reflective exposure method, the object light and the reference light are illuminated from different sides of the HOE according to the preset angle Δθ, the HOE is exposed, and the phase information and amplitude information of the object light are recorded into the In the HOE material; the reference light is then used as the reproduced light to illuminate the HOE alone along the exposure direction, and its reflected light will propagate in the propagation direction of the object light to form holographic light.

In order to evaluate the performance of HOE, some technical solutions propose to detect the exposure parameters of HOE.

As shown in Figure 2, in some technical solutions, two beam splitters (i.e., beam splitter 4 and beam splitter 5) are used to divide the light beam provided by the light source 1 into object light b1, reference light b2, and detection light b3; by adjusting the object light b1 and reference light b2, so that the object light b1 and reference light b2 are illuminated from the same side of HOE9 to expose HOE9; further adjust the detection light b3 to become the conjugate light b4 of the reference light b2, and use the conjugate light b4 as The reproduced light irradiates HOE9 alone to obtain holographic light b5; the plane mirror 10 reflects the holographic light b5 to the optical power meter 11, and the optical power meter 11 can measure the diffraction efficiency of HOE9. However, in this technical solution, the exposure optical path is large and complex to implement, and it can only measure the diffraction efficiency of HOE9, but cannot measure the refractive index change of HOE9, making the performance evaluation of HOE less accurate.

In other technical solutions, after exposing the HOE, the change in the refractive index of the HOE is measured. However, in this solution, the change in the refractive index of the HOE cannot be measured in real time, and the diffraction efficiency of the HOE cannot be measured. There is still a problem of low accuracy in the performance evaluation of the HOE.

Therefore, in the above technical solution, it is impossible to simultaneously detect the diffraction efficiency and the change in refractive index of the optical element, making the performance evaluation of the HOE less accurate.

In view of this, this application proposes a detection system and method. The system includes a first spectroscopic element, a first detection device, a linear array photoelectric receiving device and an interference element. In this system, the first beam of light from the optical element is divided into the first transmitted light and the first reflected light through the first spectroscopic element; then the first detection device can detect the light intensity change value of the first reflected light, and the first detection device can detect the change value of the light intensity of the first reflected light. The intensity change value of a reflected light is used to characterize the diffraction efficiency of the optical element; the interference element can receive the first transmitted light, obtain and project the interference fringes, and then the linear array photoelectric receiving device can obtain the image information of the interference fringes, and the image information Used to characterize the refractive index change of optical components. In this way, the diffraction efficiency and refractive index change of the optical element can be measured, and the performance of the optical element can be evaluated, which helps to improve the process of the optical element.

For example, please refer to Figure 3, which shows a possible structural diagram of the detection system provided by the embodiment of the present application. Among them, the detection system 300 includes a first spectroscopic element 301, a first detection device 302, a linear array photoelectric receiving device 303 and an interference element 304. In FIG. 3 , the detection system 300 is used to measure the refractive index change and diffraction efficiency of the optical element 100 . The first light splitting element 301 can be used to divide the first beam of light A1 from the optical element 100 into the first transmitted light A2 and the first reflected light A3. The first detection device 302 may be used to detect the light intensity change value of the first reflected light A3, and the light intensity change value of the first reflected light A3 is used to characterize the diffraction efficiency of the optical element. The interference element 304 can be used to receive the first transmitted light A2, obtain and project interference fringes. The linear array photoelectric receiving device 303 can be used to obtain image information of interference fringes, which is used to characterize the refractive index change of the optical element.

In the above detection system 300, the first beam of light from the optical element is divided into the first transmitted light and the first reflected light through the first spectroscopic element; then the first detection device can detect the change value of the light intensity of the first reflected light, The light intensity change value of the first reflected light is used to characterize the diffraction efficiency of the optical element; the interference element can receive the first transmitted light, obtain interference fringes, and project the interference fringes, and then the linear array photoelectric receiving device can obtain the image information of the interference fringes. , this image information is used to characterize the refractive index change of the optical element. In this way, the diffraction efficiency and refractive index change of the optical element can be detected, and the performance of the optical element can be evaluated, which helps to improve the process of the optical element.

It should be noted that "projecting interference fringes" can be understood as projecting interference fringes on the receiving screen (as shown in Figure 3).

It should also be noted that "the light intensity change value of the first reflected light A3 is used to characterize the diffraction efficiency of the optical element" can be understood to mean that the light intensity change value of the first reflected light A3 is used to determine the diffraction efficiency of the optical element. "The change value of the light intensity of the first reflected light A3" can be understood as the difference between the corresponding light intensities of the first reflected light A3 at the starting time and the ending time of the preset time period.

In some possible embodiments, the first detection device 302 has computing capabilities, and the first detection device 302 can determine the diffraction efficiency of the optical element according to the change value of the light intensity of the first reflected light A3.

In other possible embodiments, the first detection device 302 does not have computing power, but the above-mentioned detection system 300 also includes a control device 306 (as shown in FIG. 4 ), and the first detection device 302 can detect the first reflected light A3 The light intensity change value is sent to the control device 306, and the control device 306 can determine the diffraction efficiency of the optical element according to the light intensity change value of the first reflected light A3.

It should also be noted that "the image information is used to characterize the refractive index change of the optical element" can be understood to mean that the image information is used to determine the refractive index change of the optical element. That is to say, the changes in the interference fringes can be used to characterize the refractive index change of the optical element. The change in the refractive index of an optical element. For example, the clearer the interference fringe or the more curved the shape of the interference fringe, the larger the refractive index change.

In some possible embodiments, the linear array photoelectric receiving device 303 has computing capabilities, and the linear array photoelectric receiving device 303 can determine the refractive index change of the optical element based on the image information.

In other possible embodiments, the first detection device 302 does not have computing power, but the above-mentioned detection system 300 also includes a control device 306 (as shown in FIG. 4 ), and the first detection device 302 can send the image information to the control device 306 (as shown in FIG. 4 ). The device 306, and thus the control device 306, can determine the refractive index change amount of the optical element based on the image information.

Each functional module and structure shown in Figure 3 will be introduced and explained separately below to provide an exemplary specific implementation solution.

1. First spectroscopic element 301

In this embodiment of the present application, the first light splitting element 301 can be any element with a light splitting function. As a possible implementation manner, the first light splitting element 301 may be a spectroscope or diffractive optical elements (DOE), which is not specifically limited in the embodiment of this application.

2. First detection equipment 302

In this embodiment of the present application, the first detection device 302 may be any device with a function of detecting light intensity. As a possible implementation, the first detection device 302 may be an optical power meter.

3. Linear array photoelectric receiving device 303

In the embodiment of the present application, the linear array photoelectric receiving device 303 can be any element with the function of acquiring image information. As a possible implementation, the linear array photoelectric receiving device 303 can be a charge coupled device (CCD) camera or a complementary metal oxide semiconductor (CMOS) camera, which is not specified in the embodiment of this application. limit.

4. Interference element 304

In the embodiment of the present application, the interference element 304 can be any element with interference function. As a possible implementation, the interference element 304 may be a flat glass or a plane mirror.

5. Optical components 100

In the embodiment of the present application, the optical element 100 is the optical element to be measured, and the optical element 100 can be any optical element whose performance parameters to be measured are diffraction efficiency and refractive index change. As a possible implementation manner, the above-mentioned optical element 100 can be an HOE or other optical diffractive element, which is not specifically limited in the embodiment of the present application.

It should be noted that when the above-mentioned optical element 100 is a HOE, the first beam of light may be holographic light generated by the HOE. In the following examples, the optical element 100 is taken as an HOE to introduce the detection system 300 provided by the embodiment of the present application. Furthermore, when the above-mentioned optical element 100 is an HOE, the detection system 300 provided by the embodiment of the present application can also include an exposure light path, and the detection system 300 can detect the exposure process of the HOE to realize the diffraction efficiency and refractive index change of the HOE. detection, which can improve the exposure efficiency of HOE and improve the exposure process.

For example, please refer to FIG. 4 , which shows another possible structural diagram of the detection system provided by the embodiment of the present application. In FIG. 4 , the detection system 300 also includes an exposure light path 305 and a control device 306 . The exposure light path 305 includes a first light source, a polarization splitting element, a first shutter and a second shutter.

As shown in Figure 4, in a possible implementation, the first shutter is disposed between the first light source and the polarizing beam splitting element, and the second shutter is disposed after the polarizing beam splitting element; the first light source can be used to output the second light beam. B1, the control device 306 can control that when the first shutter is opened, the second beam of light B1 can be received by the polarizing beam splitting element; and then the polarizing beam splitting element can split the second beam of light B1 to obtain the third beam of light B2 and the fourth beam of light. B3; and the control device 306 can control the opening of the second shutter, so that the third beam of light B2 and the fourth beam of light B3 are incident on the HOE when the second shutter is opened to expose the HOE.

It should be noted that in this embodiment of the present application, the control device 306 can be any chip or integrated circuit with computing capabilities. For example, the control device 306 can be a general-purpose processor, a digital signal processor (DSP), a dedicated Integrated circuit (application specific integrated circuit, ASIC), field programmable gate array (field programmable gate array, FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general processor can be a microprocessor or any conventional processor.

It should also be noted that in the embodiment of the present application, the first light source may be a laser or other light source, which is not limited here. The laser may be, for example, at least one of an edge emitting laser (edge emitting laser, EEL), a vertical-cavity surface-emitting laser (vertical-cavity surface-emitting laser, Vcsel), or a fiber laser (fiber laser).

It should also be noted that in the embodiment of the present application, the polarizing beam splitter element is also called a polarizing beam splitter (PBS). As a possible implementation, the polarizing beam splitting element may be a polarizing beam splitting prism. Moreover, if the polarizing beam splitting element is a polarizing beam splitting prism, when the above-mentioned polarizing beam splitting element splits the second beam of light B1, the obtained third beam of light B2 and the fourth beam of light B3 are two perpendicular linearly polarized lights, that is, the third beam of light B2 and the fourth beam of light B3 are two perpendicular linearly polarized lights. The three beams of light B2 are P-polarized light, and the fourth beam of light B3 is S-polarized light. Therefore, the exposure light path 305 also includes a half-wave plate 1. The half-wave plate 1 can modulate the fourth beam of light B3 and convert the fourth beam of light B3 into S-polarized light. Light B3 is converted into P-polarized light.

It should be noted that in the embodiment of the present application, the third beam of light B2 and the fourth beam of light B3 are incident on the HOE when the second shutter is opened. When exposing the HOE, the structure of the exposure light path can be implemented in a variety of ways, as follows. Two situations are introduced respectively.

Scenario 1. Reflective exposure light path.

For example, please continue to refer to Figure 4. When the third beam of light B2 and the fourth beam of light B3 expose the HOE, the third beam of light B2 and the fourth beam of light B3 are incident on different sides of the HOE, forming a reflective Exposure light path.

Scenario 2: Transmissive exposure light path.

For example, please refer to Figure 5. When the third beam of light B2 and the fourth beam of light B3 expose the HOE, the third beam of light B2 and the fourth beam of light B3 are incident on the same side of the HOE, forming a transmission exposure. light path.

The above scenarios 1 and 2 provide the transmissive exposure light path and the reflective exposure light path of HOE, so that the exposure light path provided by the embodiment of the present application can be flexibly implemented.

Please refer to FIG. 6 , which shows another possible structural diagram of the detection system provided by the embodiment of the present application. In FIG. 6 , the exposure light path 305 in the detection system 300 may also include a second light splitting element, a first beam expansion element D1 and a second beam expansion element D2. Among them, the first beam expanding element D1 can be used to expand the third beam of light B2 to obtain the expanded third beam of light B2 ¹ ; the second beam splitting element can be used to split the fourth beam of light B3 to obtain The fifth beam of light B4 and the sixth beam of light B5; the second beam expansion element D2 can be used to expand the fifth beam of light B4 to obtain the expanded fifth beam of light B4 ¹ .

Correspondingly, when the expanded third beam of light B2 ¹ and the expanded fifth beam of light B4 ¹ are obtained, the above-mentioned third beam of light B2 and the fourth beam of light B3 are incident on the second shutter when the second shutter is opened. HOE, exposing the HOE includes: the expanded third beam of light B21 and the expanded fifth beam of light B41 incident on the HOE when the second shutter is opened, exposing the HOE.

It should be noted that in the embodiment of the present application, the first beam expansion element D1 or the second beam expansion element D2 can control the field of view range of the light beam (for example, the divergence angle of the light beam, spot size, etc.), for example, the first The beam expansion element D1 is used to expand the spot of the third beam of light B2 to obtain the expanded third beam of light B2 ¹ ; for another example, the second beam expansion element D2 can be used to expand the spot of the fifth beam of light B4 Expand to obtain the expanded fifth beam of light B4 ¹ .

It should be understood that the first beam expansion element D1 or the second beam expansion element D2 can be implemented in a variety of ways, including but not limited to the following ways:

In manner 1, the first beam expansion element D1 or the second beam expansion element D2 may include a spatial light filter and a lens.

In Mode 2, the first beam expansion element D1 or the second beam expansion element D2 may include a lens and an off-axis mirror (also called a curved mirror).

For example, please continue to refer to FIG. 6 . In FIG. 6 , the first beam expansion element D1 may include a spatial light filter and a lens, and the second beam expansion element D2 may include a lens and an off-axis mirror. It should be understood that in other possible embodiments, the first beam expansion element D1 may include a lens and an off-axis mirror, and the second beam expansion element D2 may include a spatial light filter and a lens. There are no specific limitations in the embodiments of this application.

It should also be noted that in the embodiment of the present application, the second light splitting element may be any element with a light splitting function. As a possible implementation manner, the second spectroscopic element may be a spectroscope or a DOE, which is not specifically limited in the embodiment of the present application.

In Figure 6, the third beam is expanded through the first beam expanding element, and the fourth beam is split through the second beam splitting element to obtain a fifth beam of light, and the fifth beam is expanded through the second beam expanding element. The beam is expanded, and then the expanded third beam of light and the expanded fifth beam of light are incident on the HOE when the second shutter is opened, thereby achieving exposure of the HOE. In this way, the spot and/or divergence angle of the third beam and the fourth beam can be enlarged, thereby making the HOE exposure effect better and helping to improve the HOE exposure process.

Please refer to FIG. 7 , which shows another possible structural diagram of the detection system provided by the embodiment of the present application. In FIG. 7 , the detection system 300 also includes a second detection device 307 .

As shown in Figure 7, in one possible implementation, after the second spectroscopic element splits the fourth beam of light B3 to obtain the sixth beam of light B5, the second detection device 307 can detect the sixth beam of light B5. Whether the light intensity change value is within the preset range; when the light intensity change value of the sixth beam B5 is within the preset range, the first information is sent to the control device 306 . For example, the preset range may be any one of [0, 2%], [0, 0.1%], or [0, 0.05%], which is not specifically limited in the embodiment of this application.

In this embodiment of the present application, the second detection device 307 may be any device with a function of detecting light intensity. As a possible implementation, the second detection device 307 may be an optical power meter. It can be understood that "the light intensity change value of the sixth beam of light is within the preset range" can be used to indicate that the second beam of light B1 output by the first light source is stable, and then the third beam of light B1 is obtained by splitting the second beam of light B1 through PBS. The beam B2 and the fourth beam B3 are also stable, that is, the two beams used to expose the HOE are stable. In this way, the control device controls the HOE to start exposure only after determining that the two beams used to expose the HOE are stable, which makes the exposure process of the HOE more stable and helps improve the accuracy of the performance evaluation of the HOE.

In Figure 7, by detecting the change value of the light intensity of the sixth beam of light by the second detection device 307, the stability of the second beam of light output by the first light source can be determined, thereby facilitating the control device 306 to perform the HOE exposure process. control.

Correspondingly, in a possible implementation, the control device 306 is used to control the opening of the second shutter so that the third beam of light B2 and the fourth beam of light B3 are incident on the HOE when the second shutter is opened, and the HOE is Exposure includes: the control device 306 can receive the first information from the second detection device 307. If the first information indicates that the light intensity change value of the sixth beam B5 is within the preset range, the control device 306 controls the second shutter to open. , so that the expanded third beam of light B2 ¹ and the expanded fifth beam of light B4 ¹ are incident on the HOE when the second shutter is opened, and the HOE is exposed. In this way, after determining that the second beam of light B1 emitted by the first light source is stable, the control device 306 controls the second shutter to implement exposure control of the HOE, making the exposure process of the HOE more stable.

The exposure light path in the detection system provided by the embodiment of the present application has been introduced above. The light path for HOE to generate holographic light will be introduced below. The following uses a reflective exposure light path as an example to introduce the method of generating holographic light provided by embodiments of the present application.

In the first embodiment, the control device 306 can control the second shutter to close according to a preset period, so that when the second shutter is closed, the second beam of light irradiates the HOE to obtain holographic light.

For example, please continue to refer to Figure 4. The control device 306 can also control the second shutter to close according to a preset cycle, so that when the second shutter is closed, the third beam of light B2 irradiates the HOE to obtain the holographic light A1 (i.e. first light). The preset period may be any one of 1s, 50ms, and 10ms, and there is no specific limitation in the embodiment of this application.

In the first embodiment, the control device 306 is used to control the second shutter to close, so that the third beam of light is used as the reproduction light to illuminate the HOE, so that the optical path of the detection system 300 is smaller, the implementation is simple, and the cost of the detection system 300 is effectively reduced.

In the second embodiment, a second light source is added to the detection system 300, and the HOE is irradiated with the seventh light beam output by the second light source to obtain holographic light.

For example, please refer to FIG. 8 , which shows another possible structural diagram of the detection system provided by the embodiment of the present application. In Figure 8, the detection system 300 also includes a second light source and a third shutter. Among them, the second light source can be used to output the seventh beam of light C1; the control device 306 can control the opening of the third shutter, so that when the third shutter is opened, the seventh beam of light C1 irradiates the HOE to obtain the holographic light A1 (i.e. The first beam of light); wherein the propagation direction of the seventh beam of light C1 is the same as that of the above-mentioned third beam of light B2.

It should be noted that "the propagation directions of the seven beams of light C1 and the above-mentioned third beam of light B2 are the same" can be understood to mean that the angle between the optical axes of the seven beams of light C1 and the above-mentioned third beam of light B2 is less than the threshold value. The value of the threshold may be, for example, 0.01, so that the seventh beam of light C1 can be used as reproduction light to illuminate the HOE to generate the holographic light A1 (ie, the first beam of light). Moreover, in the embodiment of the present application, the second light source may be a laser or other light source, which is not limited here.

Optionally, FIG. 8 may also include a third beam expansion element D3. The third beam expansion element D3 can expand the seventh beam of light C1 to obtain the expanded seventh beam of light C1 ¹ ; then the control device 306 can The third shutter is controlled to open, so that the seventh beam of light C1 ¹ after beam expansion can illuminate the HOE when the third shutter is opened, and obtain the holographic light A1 (that is, the first beam of light). Similarly, the propagation direction of the seventh beam of light C1 ¹ after beam expansion is the same as the above-mentioned third beam of light B2. In this way, the effect of the holographic light A1 (that is, the first beam of light) generated based on the expanded seventh beam of light C1 ¹ is better. The specific implementation of the third beam expansion element D3 is similar to that of the above-mentioned first beam expansion element D1. Please refer to the above and will not be described again here.

In the second embodiment, a second light source and a third shutter are added to the detection system 300, and the third shutter is controlled to open through the control device, so that the seventh beam of light generated by the second light source affects the HOE when the third shutter is opened. Irradiate to obtain holographic light. In this way, the control device controls the second shutter relatively simply.

It should be noted that while the detection system 300 provided by the embodiment of the present application realizes real-time detection of exposure parameters during the exposure process of HOE, it can also further control the exposure process of HOE to improve the exposure process. Among them, the detection system 300 controls the exposure process of HOE in a variety of ways, including but not limited to the following implementations:

In Embodiment 1, the above control device 306 may control the first shutter to close when the diffraction efficiency of the HOE reaches the first threshold.

It should be noted that, as shown in Figure 4, after the control device 306 controls the first shutter to close, the second beam of light B1 generated by the first light source cannot reach the polarization beam splitting element, and further the polarization beam splitting element cannot obtain the third beam of light B2 and the third beam of light B2. Four beams of light B3 are used, so that the third beam of light B2 and the fourth beam of light B3 stop exposing the HOE.

In Embodiment 1, the control device 306 may determine that the diffraction efficiency of the HOE reaches the first threshold based on the curve of the diffraction efficiency of the HOE changing with the exposure time as shown in Figure 9, and control the first shutter to close and stop exposing the HOE. , making the exposure control of HOE more in line with the user’s experimental needs.

In Embodiment 2, the above control device 306 may control the first shutter to close when the first parameter of the interference fringe reaches the second threshold.

Wherein, the first parameter includes but is not limited to width, shape or brightness contrast. It can be understood that "width" refers to the width of the interference fringe, "shape" refers to the straightness of the interference fringe (for example, the interference fringe can be annular or other shapes), and "brightness contrast" refers to the light and dark brightness contrast of the interference fringe (i.e., such as The contrast between black and white colors shown in Figure 10), the greater the contrast between light and dark brightness, the clearer the interference fringes. That is to say, the above-mentioned control device 306 can control the first shutter to close when the width of the interference fringe reaches the second threshold; or, the above-mentioned control device 306 can control the first shutter to close when the straightness of the interference fringe changes the maximum; or, The above control device 306 can control the first shutter to close when the contrast between light and dark brightness of the interference fringes is maximum.

It should be noted that the first parameter of the interference fringe is related to the change in the refractive index of the HOE. For example, the greater the change in refractive index, the clearer the interference fringes and the more curved the interference fringes. Therefore, in Embodiment 2, the control device 306 controls the first shutter to close according to the first parameter of the interference fringe (that is, the change amount of the refractive index combined with the HOE), and stops the exposure of the HOE, so that the exposure of the HOE is more suitable for the user. experimental needs.

In Embodiment 3, the above control device 306 can also control the first shutter to close when the diffraction efficiency reaches the first threshold and when the first parameter of the interference fringe reaches the second threshold.

In Embodiment 3, the diffraction efficiency and refractive index change of the HOE are simultaneously combined to control the first shutter to close and stop the exposure of the HOE, so that the exposure control of the HOE is more accurate.

Further, in a possible implementation, the control device 306 may also combine the The HOE's exposure performance is prioritized for exposure control. For example, as shown in Figure 11, the second detection device 307 takes the optical power meter 1 as an example, and the first detection device 302 takes the optical power meter 2 as an example. Correspondingly, the optical power meter 1 can collect the sixth beam of light. The light intensity change value, the optical power meter 2 can collect the diffraction efficiency of the HOE.

In Figure 11, the exposure control process includes the following steps:

S1101. The control device 306 controls the first shutter to open.

S1102. The optical power meter 1 collects the light intensity change value of the sixth beam of light.

S1103. The control device 306 determines whether the change value of the light intensity of the sixth beam of light is within a preset range.

S1104. The control device 306 determines the exposure performance priority of the HOE.

If the diffraction efficiency of the HOE is given priority, the control device 306 executes S1105A; if the refractive index change amount of the HOE is given priority, the control device 306 executes S1105B.

S1105A, perform exposure control based on the diffraction efficiency of HOE.

S1105B. Perform exposure control based on the refractive index change of HOE.

S1106. The control device 306 controls the first shutter to close.

Among them, S1105A further includes the following steps:

A1. Start exposing HOE.

A2. The control device 306 controls the second shutter to close.

A3. Optical power meter 2 collects diffraction efficiency.

A4. The control device 306 determines whether the diffraction efficiency reaches the first threshold.

If the diffraction efficiency does not reach the first threshold, the control device 306 executes step A5; if the diffraction efficiency reaches the first threshold, the control device 306 executes S1106.

A5. The control device 306 controls the opening of the second shutter.

Among them, S1105B further includes the following steps:

B1. Start exposing HOE.

B2. The control device 306 controls the second shutter to close.

B3. The CCD camera collects image information of interference fringes.

B4. The control device 306 determines whether the first parameter of the interference fringe reaches the second threshold.

If the first parameter of the interference fringe reaches the second threshold, the control device 306 executes S1106; if the first parameter of the interference fringe does not reach the second threshold, the control device 306 executes step B5.

B5. The control device 306 controls the opening of the second shutter.

Based on the above content and the same concept, embodiments of the present application also provide a detection method, which is executed by the detection system 300 shown in FIG. 3 . See Figure 12, the method includes:

S1201. The first light splitting element 301 divides the first beam of light from the optical element 100 into the first transmitted light and the first reflected light.

S1202. The first detection device 302 detects the light intensity change value of the first reflected light. The light intensity change value of the first reflected light is used to characterize the diffraction efficiency of the optical element.

S1203. The interference element 304 receives the first transmitted light and obtains interference fringes.

S1204. The interference element 304 projects interference fringes.

For example, the interference element 304 can project interference fringes onto the receiving screen.

S1205. The linear array photoelectric receiving device 303 can be used to obtain image information of interference fringes, and the image information is used to characterize the refractive index change of the optical element.

In a possible design, before the control device controls the opening of the second shutter, the method further includes: the second detection device detects whether the change value of the light intensity of the sixth beam of light is within the preset range. within; the second detection device sends the first information to the control device when the light intensity change value of the sixth beam of light is within the preset range.

In a possible design, the method further includes: controlling the device when the diffraction efficiency reaches a first threshold, and/or when the first parameter of the interference fringe reaches a second threshold. A shutter is closed; wherein the first parameter includes width, shape or brightness contrast.

For the beneficial effects of the method shown in Figure 9, please refer to the relevant description of the detection system 300, and will not be described again here.

The control device 306 provided in the embodiment of the present application may be a controller integrated with a processor, or may be a chip or circuit capable of performing functions corresponding to the above methods. The chip or circuit may be provided in a device such as a controller. Furthermore, the detection device provided by the embodiment of the present application can also be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is performed by hardware or computer software driving the hardware depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of the embodiments of the present application.

It should be noted that HOE is usually widely used in various augmented reality (augmented reality, AR) devices or holographic display devices, such as augmented reality head-up display systems (augmented reality-head up display, AR-HUD) or AR glasses. Therefore, the detection system passed by the embodiment of the present application helps to improve the HOE process by testing the performance of the HOE, thereby optimizing the performance of the equipment used in the HOE.

Those skilled in the art will understand that embodiments of the present application may be provided as methods, systems, or computer program products. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment that combines software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the present application. It will be understood that each process and/or block in the flowchart illustrations and/or block diagrams, and combinations of processes and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device produce a use A device for realizing the functions specified in one process or multiple processes of the flowchart and/or one block or multiple blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory that causes a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction means, the instructions The device implements the functions specified in a process or processes of the flowchart and/or a block or blocks of the block diagram.

These computer program instructions may also be loaded onto a computer or other programmable data processing device, causing a series of operating steps to be performed on the computer or other programmable device to produce computer-implemented processing, thereby executing on the computer or other programmable device. Instructions provide steps for implementing the functions specified in a process or processes of a flowchart diagram and/or a block or blocks of a block diagram.

Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the protection scope of the present application. In this way, if these modifications and variations of the present application fall within the scope of the claims of the present application and equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

A detection system, characterized in that the system includes a first spectroscopic element, a first detection device, a linear array photoelectric receiving device and an interference element;

The first light splitting element is used to divide the first beam of light from the optical element into the first transmitted light and the first reflected light;

The first detection device is used to detect the light intensity change value of the first reflected light, and the light intensity change value of the first reflected light is used to characterize the diffraction efficiency of the optical element;

The interference element is used to receive the first transmitted light, obtain and project interference fringes;

The linear array photoelectric receiving device is used to obtain image information of the interference fringes, and the image information is used to characterize the refractive index change of the optical element.
The system according to claim 1, wherein the optical element includes a holographic optical element HOE, and the first beam of light is holographic light.
The system according to claim 2, characterized in that the system further includes a first light source, a polarization splitting element, a first shutter, a second shutter and a control device;

The first light source is used to output a second beam of light;

The polarization splitting element is used to split the second beam of light to obtain a third beam of light and a fourth beam of light when the first shutter is opened;

The control device is used to control the opening of the second shutter, so that the third beam of light and the fourth beam of light are incident on the HOE when the second shutter is opened, and expose the HOE. .
The system according to claim 3, characterized in that the control device is also used to:

The second shutter is controlled to close according to a preset period. When the second shutter is closed, the third beam of light irradiates the HOE to obtain the holographic light.
The system of claim 3, wherein the system further includes a second light source and a third shutter;

The second light source is used to output a seventh beam of light;

The control device is also used to control the opening of the third shutter. When the third shutter is opened, the seventh beam of light irradiates the HOE to obtain the holographic light;

Wherein, the propagation direction of the seventh beam of light and the third beam of light are the same.
The system according to any one of claims 3-5, characterized in that the system further includes a second beam splitting element, a first beam expanding element, and a second beam expanding element;

The first beam expanding element is used to expand the third beam of light to obtain an expanded third beam of light; the second beam splitting element is used to split the fourth beam of light, A fifth beam of light and a sixth beam of light are obtained; the second beam expansion element is used to expand the fifth beam of light to obtain an expanded fifth beam of light;

The third beam of light and the fourth beam of light are incident on the HOE when the second shutter is opened, and exposing the HOE includes:

The expanded third beam of light and the expanded fifth beam of light are incident on the HOE when the second shutter is opened, and the HOE is exposed.
The system according to claim 6, characterized in that the system further includes a second detection device;

The control device is used to control the opening of the second shutter so that the third beam of light and the fourth beam of light are incident on the HOE when the second shutter is opened, and the HOE is exposed. When, it is specifically used for:

Receive first information from the second detection device, the first information indicating that the light intensity change value of the sixth beam of light is within a preset range;

The second shutter is controlled to open so that the expanded third beam of light and the expanded fifth beam of light are incident on the HOE when the second shutter is opened, and the HOE is exposure.
The system according to claim 7, characterized in that the second detection device is used for:

Detect whether the change value of the light intensity of the sixth beam of light is within the preset range;

When the light intensity change value of the sixth beam of light is within the preset range, the first information is sent to the control device.
The system according to any one of claims 3-8, characterized in that the control device is also used for:

When the diffraction efficiency reaches a first threshold, and/or when the first parameter of the interference fringe reaches a second threshold, control the first shutter to close;

Wherein, the first parameter includes width, shape or brightness contrast.
The system according to any one of claims 3 to 9, characterized in that when the third beam of light and the fourth beam of light expose the HOE, the third beam of light and the third beam of light Four beams of light are incident on different side surfaces of the HOE, or the third beam of light and the fourth beam of light are incident on the same side surface of the HOE.
The system according to any one of claims 6-10, wherein the first beam expansion element or the second beam expansion element includes: a spatial light filter and a lens.
The system according to any one of claims 6 to 10, characterized in that the first beam expansion element or the second beam expansion element includes: a lens and an off-axis reflector.
The system according to any one of claims 1 to 12, characterized in that the linear array photoelectric receiving device is a charge coupled device CCD camera or a complementary metal oxide semiconductor CMOS camera.
A detection method, characterized in that the method includes:

The first light splitting element divides the first beam of light from the optical element into a first transmitted light and a first reflected light;

The first detection device detects the light intensity change value of the first reflected light, and the light intensity change value of the first reflected light is used to characterize the diffraction efficiency of the optical element;

The interference element receives the first transmitted light, obtains and projects interference fringes;

The linear array photoelectric receiving device acquires image information of the interference fringes, and the image information is used to characterize the refractive index change of the optical element.
The method of claim 14, wherein the optical element is a holographic optical element HOE, and the first beam of light is holographic light.
The method of claim 15, further comprising:

When the first shutter is opened, the polarization splitting element splits the second beam of light to obtain a third beam of light and a fourth beam of light; wherein the second beam of light is output by the first light source;

The control device controls the opening of the second shutter, so that the third beam of light and the fourth beam of light are incident on the HOE when the second shutter is opened, and the HOE is exposed.
The method of claim 16, further comprising:

The control device controls the second shutter to close according to a preset period. When the second shutter is closed, the third beam of light irradiates the HOE to obtain the holographic light.
The method of claim 16, further comprising:

The control device controls the opening of the third shutter so that the seventh beam of light irradiates the HOE when the third shutter is opened to obtain the holographic light;

Wherein, the seventh beam of light is output by the second light source, and the propagation direction of the seventh beam of light and the third beam of light is the same.
The method according to any one of claims 16-18, characterized in that the method further includes:

The first beam expanding element expands the third beam of light to obtain an expanded third beam of light;

The second spectroscopic element splits the fourth beam of light to obtain a fifth beam of light and a sixth beam of light;

The second beam expanding element expands the fifth beam of light to obtain an expanded fifth beam of light;

The third beam of light and the fourth beam of light are incident on the HOE when the second shutter is opened, and exposing the HOE includes:

The expanded third beam of light and the expanded fifth beam of light are incident on the HOE when the second shutter is opened, and the HOE is exposed.
The method of claim 19, wherein the control device controls the opening of the second shutter so that the third beam of light and the fourth beam of light are incident on the second shutter when the second shutter is opened. HOE, exposure of said HOE, including:

The control device receives first information from the second detection device, the first information indicating that the light intensity change value of the sixth beam of light is within a preset range;

The control device controls the opening of the second shutter so that the expanded third beam of light and the expanded fifth beam of light are incident on the HOE when the second shutter is opened. The HOE performs the exposure.
The method according to claim 20, characterized in that before the control device controls the opening of the second shutter, the method further includes:

The second detection device detects whether the change value of the light intensity of the sixth beam of light is within the preset range;

The second detection device sends the first information to the control device when the light intensity change value of the sixth beam of light is within the preset range.
The method according to any one of claims 16-21, characterized in that the method further includes:

The control device controls the first shutter to close when the diffraction efficiency reaches a first threshold, and/or when the first parameter of the interference fringe reaches a second threshold;

Wherein, the first parameter includes width, shape or brightness contrast.