Optical module ghost detection method and detection device
By projecting different circularly polarized lights using a detection device and detecting the intensity of reflected and transmitted light from the optical module, the ghosting phenomenon in the pancake optical structure was solved, thus improving the imaging quality of VR devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GOERTEK OPTICAL TECH CO LTD
- Filing Date
- 2023-12-21
- Publication Date
- 2026-07-21
AI Technical Summary
The inaccurate polarization state of the pancake optical structure in existing VR devices leads to severe stray light, resulting in ghosting and affecting the user experience.
The detection device includes a first optical power meter, a second optical power meter, and a light source module. By projecting different circularly polarized light onto the optical module, the light intensity of reflected and transmitted light is detected respectively, and optical parameters are calculated to assess the degree of ghosting.
Effectively assessing the degree of ghosting produced by the optical module improves the imaging quality of VR devices.
Smart Images
Figure CN117848674B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical module testing technology, and more specifically, to an optical module ghost detection method and device. Background Technology
[0002] With the advancement of technology and the improvement of living standards, the demand for VR technology is growing rapidly across all industries. As VR devices are constantly being updated and upgraded, their immersiveness and interactivity are also gradually improving. Among these, the pancake optical structure, as the most widely used optical structure in VR devices, offers a folding optical path design that greatly enhances the thinness and convenience of VR devices.
[0003] However, the folded-back optical path requires a high degree of control over the polarization state of the light. When the optical film manufacturing process and bonding process are poor, the inaccurate polarization state during the folding-back of the optical path will lead to severe stray light, and the resulting series of ghosting phenomena will affect the quality of user experience.
[0004] Therefore, it is necessary to provide a method and device for detecting ghosting in optical modules. Summary of the Invention
[0005] The purpose of this application is to provide a new technical solution for optical module ghost detection method and detection device.
[0006] Firstly, embodiments of this application provide a method for detecting ghosting in an optical module. A detection device is used to detect the optical module. The detection device includes a first optical power meter, a second optical power meter, and a light source module. The light source module is configured to project first and second circularly polarized light onto the optical module. The optical module is sequentially provided with a beam-splitting element, a phase retardation film, a polarization reflection film, and a polarizing film.
[0007] The optical module ghost detection method includes:
[0008] A first circularly polarized light is emitted into the optical module. The first optical power meter receives the light reflected by the polarization reflection film and passes through the phase retardation film for the second time and obtains the light intensity W1. The second optical power meter receives the light transmitted by the polarization reflection film and obtains the light intensity W2.
[0009] A second circularly polarized light is emitted into the optical module. The first optical power meter receives the light reflected by the optical module and obtains the light intensity W3. The second optical power meter receives the light transmitted by the polarizing reflective film and obtains the light intensity W4.
[0010] The optical parameters are determined based on the light intensity W1, the light intensity W2, the light intensity W3, and the light intensity W4.
[0011] The degree of ghosting produced by the optical module is determined based on the optical parameters.
[0012] Optionally, the first optical power receiving of the light reflected by the polarization reflective film and passing through the phase retardation film a second time specifically includes:
[0013] A first quarter-wave plate and a first polarizer are disposed between the first optical power meter and the optical module;
[0014] The light reflected by the beam splitter is filtered by the first polarizer after passing through the first quarter-wave plate.
[0015] The light rays reflected by the polarizing reflective film and then passing through the phase delay film for the second time are received by the first optical power meter after passing through the first quarter-wave plate and the first polarizer in sequence.
[0016] Optionally, the light reflected by the optical module specifically includes:
[0017] The light reflected by the beam splitter and the light reflected by the polarizing reflective film and then passing through the phase retardation film a second time.
[0018] Optionally, the first circularly polarized light is modulated into a first linearly polarized light by the phase retardation film for the first time, and the second circularly polarized light is modulated into a second linearly polarized light by the phase retardation film for the first time. The polarization reflection film reflects the first linearly polarized light and transmits the second linearly polarized light.
[0019] Optionally, the optical parameters are determined based on the light intensity W1, the light intensity W2, the light intensity W3, and the light intensity W4 as follows:
[0020] 1 / 2(W2 / W1+W3 / W4).
[0021] Optionally, the first circularly polarized light is either a right-handed circularly polarized light or a left-handed circularly polarized light, and the second circularly polarized light is either a right-handed circularly polarized light or a left-handed circularly polarized light.
[0022] Secondly, embodiments of this application provide an optical module ghost detection device. The optical module ghost detection device uses the optical module ghost detection method as described in the first aspect to detect the optical module;
[0023] The optical module ghost detection device includes:
[0024] A light source module is used to project first circularly polarized light and second circularly polarized light onto the optical module;
[0025] The first optical power meter is placed in the optical path of the reflected light from the optical module;
[0026] The second optical power meter is placed in the optical path of the transmitted light of the optical module.
[0027] Optionally, the optical module ghost detection device further includes: a first quarter-wave plate and a first polarizer;
[0028] The first quarter-wave plate and the first polarizer are located between the optical module and the first optical power meter, and the first polarizer is closer to the first optical power meter than the first quarter-wave plate.
[0029] Optionally, the light source module includes a light source body, a second polarizer, and a second quarter-wave plate;
[0030] The second polarizer is closer to the light source body than the second quarter-wave plate;
[0031] The quarter-wave plate is configured to rotate so that the light source module emits a first circularly polarized light and a second circularly polarized light.
[0032] Optionally, when the angle between the fast axis of the quarter-wave plate and the polarization direction of the polarizer is +45°, the light source module emits left-handed circularly polarized light; when the angle between the fast axis of the quarter-wave plate and the polarization direction of the polarizer is -45°, the light source module emits right-handed circularly polarized light.
[0033] According to an embodiment of this application, an optical module ghost detection method is provided. By emitting circularly polarized light with different polarization states into the optical module, a first optical power meter and a second optical power meter respectively detect the light intensity of the transmitted light and the light intensity of the reflected light from the optical module, and determine the degree of ghosting generated by the optical module based on the light intensity.
[0034] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description
[0035] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.
[0036] Figure 1 The diagram shows a flowchart of the optical module ghost detection method provided in an embodiment of this application.
[0037] Figure 2 The diagram shown is a structural diagram of the optical module ghost detection device provided in an embodiment of this application.
[0038] Figure 3 The diagram shows the optical path for detecting reflected light in the optical module detection device.
[0039] Figure 4 The diagram shows the transmission optical path of the optical module testing device.
[0040] Figure 5 The diagram shown is an optical architecture diagram of an optical module.
[0041] Explanation of reference numerals in the attached figures:
[0042] 10. Light source body; 11. Second polarizer; 12. Second quarter-wave plate;
[0043] 2. First optical power meter;
[0044] 3. Third optical power meter;
[0045] 41. First quarter-wave plate; 42. First polarizer;
[0046] 5. Optical module; 51. Beam splitter; 52. Phase retardation film; 53. Polarizing reflective film; 54. Polarizing film. Detailed Implementation
[0047] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the present application.
[0048] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.
[0049] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.
[0050] In all the examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.
[0051] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.
[0052] This application provides a method for detecting ghosting in an optical module. The optical module 5 detection device uses this method to detect ghosting in the optical module 5. (Refer to...) Figures 2-4The detection device includes a first optical power meter 2, a second optical power meter 3, and a light source module. The light source module is configured to project first circularly polarized light and second circularly polarized light onto the optical module 5. The optical module 5 is sequentially provided with a beam splitter 51, a phase retardation film 52, a polarization reflection film 53, and a polarizing film 54.
[0053] Specifically, the optical module 5 detection device includes a first optical power meter 2, a second optical power meter 3, and a light source module. The first optical power meter 2 receives the light transmitted to it and can obtain the intensity of the corresponding light. The first optical power meter 2 is placed in the optical path of the reflected light from the optical module 5. The type of reflected light received by the first optical power meter 2 is related to the type of light projected from the light source module to the optical module 5. The second optical power meter 3 receives the light transmitted to it and can obtain the intensity of the corresponding light. The first optical power meter 2 is placed in the optical path of the transmitted light from the optical module 5. The type of transmitted light received by the second optical power meter 3 is related to the type of light projected from the light source module to the optical module 5. The light source module is used to emit circularly polarized light. Specifically, the light source module can emit first circularly polarized light and second circularly polarized light. The user can make the light source module emit the corresponding circularly polarized light according to actual needs.
[0054] In the embodiments of this application, reference is made to Figure 5 The specific optical architecture of the optical module 5 is not limited. For example, the optical module 5 may include one lens, two lenses, three lenses, or more lenses. The phase retardation film 52, polarizing reflection film 53, and polarizing film 54 (polarizing transmission film) included in the optical module 5 can all be independent single film layers, or two or three of the phase retardation film 52, polarizing reflection film 53, and polarizing film 54 can be combined to form a composite film layer. Regardless of whether it is a single film layer structure or a composite film layer structure, the arrangement order of the beam splitter 51, phase retardation film 52, polarizing reflection film 53, and polarizing film 54 in the optical module 5 must satisfy the condition that, in the direction away from the display screen, the order is beam splitter 51, phase retardation film 52, polarizing reflection film 53, and polarizing film 54. Figure 5 This illustration shows a monolithic lens with a composite film layer, which is a combination of a phase retardation film 52, a polarizing reflection film 53, and a polarizing film 54. (Refer to...) Figure 5 The optical module consists of a display screen, a lens, and an aperture stop along the optical axis. The aperture stop, acting as an aperture stop, controls the amount of light passing through, thereby adjusting the luminous flux of the optical system and reducing the influence of non-imaging light. In this embodiment, the surface of the lens furthest from the display screen is planar, while the surface closest to the display screen is aspherical and satisfies the following formula:
[0055]
[0056] Where r is the center height of the lens, z is the displacement difference between the aspherical structure and the surface vertex at height r along the optical axis, c is the vertex radius of curvature of the aspherical surface, k is the conic coefficient, and α i Let represent the aspherical coefficient of the i-th term.
[0057] It should be noted that there are no special restrictions on the number of lenses or the surface shape of the lenses in optical module 5.
[0058] Reference Figure 1 This paper provides a method for detecting ghosting in an optical module. The method involves emitting circularly polarized light of different polarization states from a light source module to an optical module 5. The circularly polarized light of different polarization states passes through the optical module 5 and reaches a second optical power meter 3. Alternatively, the circularly polarized light of different polarization states is reflected and passes through a phase retardation film 52 again to reach a first optical power meter 2. The first optical power meter 2 and the second optical power meter 3 obtain the intensity of the light received when the incident light of different polarization states is used to measure the strength of ghosting during imaging of the optical module 5.
[0059] Specifically, the optical module 5 includes a beam splitter 51, a phase retardation film 52, a polarizing reflective film 53, and a polarizing film 54 arranged sequentially; therefore, the optical module 5 is a pancake optical module 5. In the light transmission of the pancake optical module 5, the optical path is a folded-back optical path. In this folded-back optical path, the polarization state of the light when it first encounters the polarizing reflective film 53 is different from the polarization state of the light when it encounters the polarizing reflective film 53 for the second time. The light is reflected when it first encounters the polarizing reflective film 53, and transmitted when it encounters the polarizing reflective film 53 for the second time. This application assesses the degree of ghosting produced by the optical module 5 by obtaining the light intensity (normal light) of the light reflected when it first encounters the polarizing reflective film 53, and the light intensity (stray light) of the light transmitted when it first encounters the polarizing reflective film 53, and by obtaining the light intensity (normal light) of the light transmitted when it second encounters the polarizing reflective film 53, and the light intensity (stray light) of the light reflected when it second encounters the polarizing reflective film 53.
[0060] In this embodiment of the application, the optical module ghost detection method includes the following steps:
[0061] S101: The first circularly polarized light is emitted into the optical module 5. The first optical power meter 2 receives the light reflected by the polarization reflection film 53 and passes through the phase retardation film 52 for the second time and obtains the light intensity W1. The second optical power meter 3 receives the light transmitted by the polarization reflection film 53 and obtains the light intensity W2.
[0062] S102: A second circularly polarized light is emitted into the optical module 5. The first optical power meter 2 receives the light reflected by the optical module 5 and obtains the light intensity W3. The second optical power meter 3 receives the light transmitted by the polarizing reflective film 53 and obtains the light intensity W4.
[0063] S103: Determine the optical parameters based on the light intensity W1, the light intensity W2, the light intensity W3, and the light intensity W4;
[0064] S104: Determine the degree of ghosting produced by optical module 5 based on the optical parameters.
[0065] In step S101, the first circularly polarized light is emitted from the light source module to the optical module 5. For example, if the first circularly polarized light is right-handed circularly polarized, the second circularly polarized light is left-handed circularly polarized. Or, for example, if the first circularly polarized light is left-handed circularly polarized, the second circularly polarized light is right-handed circularly polarized.
[0066] Regardless of the type of circularly polarized light emitted from the light source module to the optical module 5, the light received by the first optical power meter 2 and the second optical power meter 3 will consist of two types: normal light and stray light. For example, if the light received by the first optical power meter 2 is stray light, the light received by the second optical power meter 3 will be normal light.
[0067] Since in this step, the first optical power meter 2 is limited to receiving light that has been reflected by the polarization reflection film 53 and passed through the phase delay film 52 for the second time, step S101 simulates the situation where the light passes through the polarization reflection film 53 for the first time and is reflected by the polarization reflection film 53 in the folded optical path. At this time, the light intensity received by the first optical power meter 2 is the light intensity of normal light, and the light intensity received by the second optical power meter 3 is the light intensity of stray light.
[0068] Therefore, in step S101, when the first circularly polarized light is projected onto the optical module 5, the light intensity of the stray light emitted by the optical module 5 and the light intensity of the normal light emitted by the optical module 5 are obtained by the first optical power meter 2 and the second optical power meter 3.
[0069] In step S102, a second circularly polarized light is emitted from the light source module to the optical module 5. For example, if the first circularly polarized light is right-handed circularly polarized, the second circularly polarized light is left-handed circularly polarized. Or, for example, if the first circularly polarized light is left-handed circularly polarized, the second circularly polarized light is right-handed circularly polarized.
[0070] Regardless of the type of circularly polarized light emitted from the light source module to the optical module 5, the light received by the first optical power meter 2 and the second optical power meter 3 will consist of two types: normal light and stray light. For example, if the light received by the first optical power meter 2 is stray light, the light received by the second optical power meter 3 will be normal light.
[0071] Since the first optical power meter 2 receives the light intensity of all the light reflected by the optical module 5 in step S102, step S102 simulates the situation where the light passes through the polarization reflection film 53 for the second time in the folded optical path and is transmitted by the polarization reflection film 53. At this time, the first optical power meter 2 receives the light intensity of stray light, and the second optical power meter 3 receives the light intensity of normal light.
[0072] Therefore, in step S102, when the second circularly polarized light is projected onto the optical module 5, the light intensity of the stray light emitted by the optical module 5 and the light intensity of the normal light emitted by the optical module 5 are obtained by the first optical power meter 2 and the second optical power meter 3.
[0073] It should be noted that the order of steps S101 and S102 can be interchanged. For example, the first circularly polarized light can be projected onto the optical module 5 through the light source module first, and then the second circularly polarized light can be projected onto the optical module 5 through the light source module; or the second circularly polarized light can be projected onto the optical module 5 through the light source module first, and then the first circularly polarized light can be projected onto the optical module 5 through the light source module.
[0074] Therefore, in this embodiment of the application, in steps S101 and S102, a total of four parameters are obtained by the first optical power meter 2 and the second optical power meter 3. The four parameters are the light intensity of stray light emitted by the optical module 5 and the light intensity of normal light emitted by the optical module 5 when the first circularly polarized light is projected onto the optical module 5, and the light intensity of normal light emitted by the optical module 5 and the light intensity of stray light emitted by the optical module 5 when the second circularly polarized light is projected onto the optical module 5.
[0075] In step S103, optical parameters are determined based on light intensity W1, light intensity W2, light intensity W3 and light intensity W4. Specifically, the ratio of stray light intensity to normal light intensity is determined based on light intensity W1, light intensity W2, light intensity W3 and light intensity W4.
[0076] In step S104, the degree of ghosting produced by the optical module 5 is determined based on optical parameters. Specifically, the ratio of stray light intensity to normal light intensity is determined based on light intensities W1, W2, W3, and W4. When the ratio of stray light intensity to normal light intensity is small, the degree of ghosting produced by the optical module 5 is weak; when the ratio of stray light intensity to normal light intensity is large, the degree of ghosting produced by the optical module 5 is strong.
[0077] Therefore, in this embodiment of the application, an optical module ghost detection method is provided. By emitting circularly polarized light with different polarization states into the optical module 5, the first optical power meter 2 and the second optical power meter 3 respectively detect the light intensity of the transmitted light and the light intensity of the reflected light of the optical module 5, and determine the degree of ghosting generated by the optical module 5 based on the light intensity.
[0078] In one specific embodiment, the light source module emits right-handed circularly polarized light into the optical module 5, and the polarization reflective film 53 is designed to reflect light. Directional polarization, transmission Taking linearly polarized light as an example, the first optical power meter 2 receives most of the light reflected by the polarizing reflective film 53, which is normal light. The second optical power meter 3 receives a small portion of the light transmitted through the polarizing reflective film 53, which is stray light.
[0079] When the light source module projects right-hand circularly polarized light onto the optical module 5, let the Jones vector of this polarized light be... Light passes through the Jones matrix of phase retardation film 52 After modulation, right-handed circularly polarized light becomes linearly polarized light. The polarizing reflective film 53 is theoretically designed for reflection. Direction, through The light is linearly polarized, but the actual bonding process causes a rotation error in the optical axis of the polarizing reflective film 53. This results in a small portion of the light passing through the polarizing reflective film 53, while most of the light is reflected and passes through the phase retardation film 52, and then through the Jones matrix. After re-modulation, the linearly polarized light becomes left-handed circularly polarized light. Then, the light is emitted again through the lens and received by the first optical power meter 2. At this time, the first optical power meter 2 measures the received light intensity W1 to evaluate normal light, and the second optical power meter 3 measures the received light intensity W2 to evaluate stray light.
[0080] When the light source module projects left-handed circularly polarized light onto the optical module 5, 设 Jones vector of this polarized light When light enters the lens, some of it is reflected by the upper surface of the lens, while the rest passes through the lens and reaches the phase retardation film 52, where it passes through the Jones matrix of the phase retardation film 52. After modulation, left-handed circularly polarized light becomes linearly polarized light. The polarizing reflective film 53 is theoretically designed for reflection. Direction, through The light is linearly polarized, but the actual difference causes a small portion of the light to be reflected, while most of the light reaches the polarization projection film after transmission. Stray light is assessed by measuring the received light intensity W3 using a first optical power meter 2, and normal light is assessed by measuring the received light intensity W4 using a second optical power meter 3.
[0081] Therefore, in this specific embodiment, the degree to which the optical module 5 produces ghosting is determined by the light intensity W1 of the normal light received by the first optical power meter 2, the light intensity W2 of the stray light received by the second optical power meter 3, the light intensity W3 of the stray light received by the first optical power meter 2, and the light intensity W4 of the normal light received by the second optical power meter 3.
[0082] In one embodiment, the first optical power receiving of light reflected by the polarization reflective film 53 and passing through the phase retardation film 52 a second time specifically includes:
[0083] A first quarter-wave plate 41 and a first polarizer 42 are disposed between the first optical power meter 2 and the optical module 5;
[0084] The light reflected by the beam splitter 51 is filtered by the first polarizer 42 after passing through the first quarter-wave plate 41.
[0085] The light rays reflected by the polarizing reflective film 53 and then passing through the phase delay film 52 for the second time are received by the first optical power meter 2 after passing through the first quarter-wave plate 41 and the first polarizer 42 in sequence.
[0086] In this embodiment, when the first circularly polarized light is emitted into the optical module 5, in order to ensure that the reflected light received by the first optical power meter 2 is the light reflected by the polarization reflection film 53 and passes through the phase delay film 52 for the second time, it is necessary to filter out the light reflected by the upper surface of the lens when the light enters the lens, so as to ensure that the intensity of the light received by the first optical power meter 2 is the intensity of normal light.
[0087] Specifically, a first quarter-wave plate 41 and a first polarizer 42 are disposed between the first optical power meter 2 and the optical module 5, so as to filter out the light reflected by the upper surface of the lens of the optical module 5 (the surface close to the display screen).
[0088] For example, when optical module 5 emits first circularly polarized light, the polarization state of the light reflected by the lens surface is first circularly polarized light; when optical module 5 emits first circularly polarized light, the polarization state of the light reflected by polarizing reflective film 53 and passing through phase retardation film 52 a second time is second circularly polarized light. Here, the first quarter-wave plate 41 and the first polarizer 42 are used to convert the first circularly polarized light into first linearly polarized light, and the second circularly polarized light into second linearly polarized light, and the first linearly polarized light is filtered out by the first polarizer 42.
[0089] For example, if the first circularly polarized light is right-handed and the second circularly polarized light is left-handed, then the first quarter-wave plate can be used. Make right-handed circular polarizer Transformed into linearly polarized light Left-handed circular polarizer Transformed into linearly polarized light Then it is filtered out by the first polarizer 42 Linear polarized light.
[0090] In one embodiment, the light reflected by the optical module 5 specifically includes:
[0091] The light reflected by the beam splitter 51 and the light reflected by the polarizing reflective film 53 and then passing through the phase retardation film 52 for the second time.
[0092] In this embodiment, the light reflected by the optical module 5 includes two types of light: one is light emitted from the light source module that is projected onto the optical module 5 and reflected by the lens surface of the optical module 5; the other is light emitted from the light source module that is projected onto the optical module 5, passes sequentially through the beam splitter 51 and the phase retardation film 52, is reflected by the polarization reflection film 53 of the optical module 5, and passes through the phase retardation film 52 a second time.
[0093] When the second circularly polarized light is projected onto the optical module 5 through the light source module, the first optical power meter 2 receives all the reflected stray light. Therefore, the light reflected by the beam splitter 51 and the light reflected by the polarizing reflective film 53 and then passing through the phase delay film 52 for the second time are both received by the first optical power meter 2.
[0094] In one embodiment, the first circularly polarized light is modulated into a first linearly polarized light by the phase retardation film 52 for the first time, and the second circularly polarized light is modulated into a second linearly polarized light by the phase retardation film 52 for the first time. The polarization reflection film 53 reflects the first linearly polarized light and transmits the second linearly polarized light.
[0095] In this embodiment, reference is made to Figure 3This is a schematic diagram of the optical path for detecting reflected light in the optical module 5. When the incident light projected from the light source module to the optical module 5 is first circularly polarized light, a portion of it is reflected by the upper surface of the lens, while the other portion passes through the lens and reaches the phase retardation film 52. After being modulated by the phase retardation film 52, the first circularly polarized light becomes first linearly polarized light. The polarization reflection film 53 is theoretically designed to reflect the first linearly polarized light and transmit the second linearly polarized light. However, the actual bonding process causes a rotation error in the optical axis of the polarization reflection film 53, resulting in a small portion of the light passing through the polarization reflection film 53, while most of the light is reflected and then reaches the phase retardation film 52 again. After being reflected and re-modulated by the phase retardation film 52, the first linearly polarized light becomes second circularly polarized light, and then passes through the optical module 5 again before entering the first optical power meter 2. Since a portion of the light incident through the first circularly polarized incident lens is reflected by its upper surface, the influence of this light needs to be filtered out. Therefore, a first quarter-wave plate 41 is used to convert the first circularly polarized light into a first linearly polarized light, and the second circularly polarized light into a second linearly polarized light. The first linearly polarized light is then filtered out by a first polarizer 42. Finally, the received light intensity W1 is measured by a first optical power meter 2 to determine normal light, and the received light intensity is measured by a second optical power meter 3W2 to determine stray light.
[0096] Reference Figure 4 This is a schematic diagram of the transmitted light path for the optical module 5 testing equipment. When the incident light projected from the light source module to the optical module 5 is second circularly polarized light, when the incident light enters the lens of the optical module 5, part of the light will still be reflected by the upper surface, and the other part will pass through the lens to reach the phase retardation film 52. After being modulated by the phase retardation film 52, the second circularly polarized light becomes second linearly polarized light. The polarization reflection film 53 is theoretically designed to reflect the first linearly polarized light and transmit the second linearly polarized light, but in reality, a small portion of the light is reflected, and most of the light is transmitted to the polarization transmission film. The light intensity W3 of the light reflected by the optical module 5 is received by the first optical power meter 2 to evaluate stray light, and the light intensity W4 of the received light is measured by the second optical power meter 3 to evaluate normal light.
[0097] In one embodiment, determining the optical parameters based on the light intensity W1, the light intensity W2, the light intensity W3, and the light intensity W4 specifically involves:
[0098] 1 / 2(W2 / W1 + W3 / W4)
[0099] In this embodiment, when the first and second circularly polarized rays are incident on the optical module 5, they simulate the states of the optical path reaching the film material for the first and second time in a normal imaging folding optical path. The stray light intensity divided by the average of the normal light intensity, i.e., 1 / 2 (W2 / W1 + W3 / W4), can be used as a measure of the ghosting degree of the optical module 5. When the optical parameter values are large, meaning the stray light intensity accounts for a large proportion, the optical module 5 produces a greater degree of ghosting. When the optical parameter values are small, meaning the stray light intensity accounts for a small proportion, the optical module 5 produces a smaller degree of ghosting.
[0100] Secondly, this application also provides an optical module ghost detection device. The optical module ghost detection device uses the optical module ghost detection method described above to detect the optical module 5.
[0101] The optical module ghost detection device includes:
[0102] A light source module is used to project first circularly polarized light and second circularly polarized light onto the optical module 5;
[0103] The first optical power meter 2 is placed in the optical path of the reflected light from the optical module 5;
[0104] The second optical power meter 3 is placed in the optical path of the transmitted light of the optical module 5.
[0105] In this embodiment, the optical module ghost detection device includes a light source module, a first optical power meter 2, and a second optical power meter 3. The light source module can emit first circularly polarized light and second circularly polarized light.
[0106] The optical module 5 includes a beam splitter 51, a phase retardation film 52, a polarizing reflective film 53, and a polarizing film 54 arranged sequentially; therefore, the optical module 5 is a pancake optical module 5. In the light transmission of the pancake optical module 5, the optical path is a folded-back optical path. During normal imaging of the optical module 5, when the light in the folded-back optical path first reaches the film material (polarizing reflective film 53), it is reflected by the film material. The light reflected by the film material is normal light, and the light transmitted by the film material is stray light. During normal imaging of the optical module 5, when the light in the folded-back optical path reaches the film material a second time, it is transmitted by the film material. The light transmitted by the film material is normal light, and the light reflected by the film material is stray light. In order to obtain the intensity of the light reflected from the membrane material when it first reaches the membrane material in the folded-back optical path, as well as the intensity of the light transmitted through the membrane material, and in order to obtain the intensity of the light transmitted through the membrane material when it second reaches the membrane material in the folded-back optical path, as well as the intensity of the light reflected by the membrane material, in this embodiment, the first optical power meter 2 is placed in the optical path of the reflected light of the optical module 5, and the second optical power meter 3 is placed in the optical path of the transmitted light of the optical module 5.
[0107] In one embodiment, the optical module ghost detection device further includes: a first quarter-wave plate 41 and a first polarizer 42;
[0108] The first quarter-wave plate 41 and the first polarizer 42 are located between the optical module 5 and the first optical power meter 2, and the first polarizer 42 is closer to the first optical power meter 2 than the first quarter-wave plate 41.
[0109] In this embodiment, when the first circularly polarized light is emitted into the optical module 5, in order to ensure that the reflected light received by the first optical power meter 2 is the light reflected by the polarization reflection film 53 and passes through the phase delay film 52 for the second time, it is necessary to filter out the light reflected by the upper surface of the lens when the light enters the lens, so as to ensure that the intensity of the light received by the first optical power meter 2 is the intensity of normal light.
[0110] Specifically, a first quarter-wave plate 41 and a first polarizer 42 are disposed between the first optical power meter 2 and the optical module 5, so as to filter out the light reflected by the upper surface of the lens of the optical module 5 (the surface close to the display screen).
[0111] In one embodiment, the light source module includes a light source body 10, a second polarizer 11, and a second quarter-wave plate 12. For example, the light source body 10 may include, but is not limited to, a laser.
[0112] The second polarizer 11 is closer to the light source body 10 than the second quarter-wave plate 12;
[0113] The quarter-wave plate is configured to rotate so that the light source module emits a first circularly polarized light and a second circularly polarized light.
[0114] In this embodiment, to enable the light source module to emit both first and second circularly polarized light, the light source module includes a second polarizer 11 and a second quarter-wave plate 12. The light emitted from the light source module forms linearly polarized light after passing through the second polarizer 11, and then forms circularly polarized light after passing through the second quarter-wave plate 12, whose optical axis differs from that of the second polarizer 11 by 45°. Since it is necessary to measure the light rays that pass through the film material for the first and second time during the normal imaging process of the optical module 5, the second quarter-wave plate 12 is configured with two rotatable positions differing by 90°, thereby allowing adjustment of the laser polarization state to either first or second circularly polarized light.
[0115] In one specific embodiment, when the fast axis of the second quarter-wave plate 12 is rotated such that the polarization direction of the second polarizer 11 is +45°, the light source module emits left-handed circularly polarized light; when the fast axis of the second quarter-wave plate 12 is rotated such that the polarization direction of the second polarizer 11 is -45°, the light source module emits right-handed circularly polarized light.
[0116] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.
[0117] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.
Claims
1. A method for detecting ghosting in an optical module, characterized in that, The detection is performed using a detection device, which includes a first optical power meter, a second optical power meter, and a light source module. The light source module is configured to project a first circularly polarized beam and a second circularly polarized beam onto an optical module. The optical module is sequentially provided with a beam splitter, a phase retardation film, a polarization reflection film, and a polarizing film. The first circularly polarized beam and the second circularly polarized beam have opposite rotation directions. The optical module ghost detection method includes: A first circularly polarized light is emitted into the optical module. The first optical power meter receives the light reflected by the polarization reflection film and passes through the phase retardation film for the second time and obtains the light intensity W1. The second optical power meter receives the light transmitted by the polarization reflection film and obtains the light intensity W2. A second circularly polarized light is emitted into the optical module. The first optical power meter receives the light reflected by the optical module and obtains the light intensity W3. The second optical power meter receives the light transmitted by the polarizing reflective film and obtains the light intensity W4. Optical parameters are determined based on the light intensity W1, the light intensity W2, the light intensity W3, and the light intensity W4, wherein determining the optical parameters based on the light intensity W1, the light intensity W2, the light intensity W3, and the light intensity W4 specifically involves: ； The degree of ghosting produced by the optical module is determined based on the optical parameters.
2. The optical module ghost detection method according to claim 1, characterized in that, The first optical power meter receives light rays that have been reflected by the polarization reflection film and then passed through the phase retardation film a second time, specifically including: A first quarter-wave plate and a first polarizer are disposed between the first optical power meter and the optical module; The light reflected by the beam splitter is filtered by the first polarizer after passing through the first quarter-wave plate. The light rays reflected by the polarizing reflective film and then passing through the phase delay film for the second time are received by the first optical power meter after passing through the first quarter-wave plate and the first polarizer in sequence.
3. The optical module ghost detection method according to claim 1, characterized in that, The light reflected by the optical module specifically includes: The light reflected by the beam splitter and the light reflected by the polarizing reflective film and then passing through the phase retardation film a second time.
4. The optical module ghost detection method according to claim 1, characterized in that, The first circularly polarized light is modulated into a first linearly polarized light by the phase retardation film for the first time, and the second circularly polarized light is modulated into a second linearly polarized light by the phase retardation film for the first time. The polarization reflection film reflects the first linearly polarized light and transmits the second linearly polarized light.
5. The optical module ghost detection method according to claim 1, characterized in that, The first circularly polarized light is either a right-handed circularly polarized light or a left-handed circularly polarized light, and the second circularly polarized light is either a right-handed circularly polarized light or a left-handed circularly polarized light.
6. An optical module ghost detection device, characterized in that, The optical module ghost detection device uses the optical module ghost detection method as described in any one of claims 1-5 to detect the optical module; The optical module ghost detection device includes: A light source module is used to project first circularly polarized light and second circularly polarized light onto the optical module; The first optical power meter is placed in the optical path of the reflected light from the optical module; The second optical power meter is placed in the optical path of the transmitted light of the optical module.
7. The optical module ghost detection device according to claim 6, characterized in that, The optical module ghost detection device further includes: a first quarter-wave plate and a first polarizer; The first quarter-wave plate and the first polarizer are located between the optical module and the first optical power meter, and the first polarizer is closer to the first optical power meter than the first quarter-wave plate.
8. The optical module ghost detection device according to claim 6, characterized in that, The light source module includes a light source body, a second polarizer, and a second quarter-wave plate; The second polarizer is closer to the light source body than the second quarter-wave plate; The second quarter-wave plate is configured to rotate so that the light source module emits a first circularly polarized light and a second circularly polarized light.
9. The optical module ghost detection device according to claim 8, characterized in that, When the angle between the fast axis of the quarter-wave plate and the polarization direction of the polarizer is +45°, the light source module emits left-handed circularly polarized light; when the angle between the fast axis of the quarter-wave plate and the polarization direction of the polarizer is -45°, the light source module emits right-handed circularly polarized light.