Optical module, near-eye display device and light projection method

Abstract

The present invention provides an optical module, comprising: a first phase delay unit, configured to modulate the incident light beam into circular polarization or elliptically polarized light; a semi-transparent and semi-reflective layer, located downstream of the optical path of the first phase delay unit and receiving the circular polarization or elliptically polarized light; a second phase delay unit, located downstream of the optical path of the semi-transparent and semi-reflective layer; and a polarization beam splitter, arranged downstream of the optical path of the second phase delay unit, the polarization beam splitter having a light transmission axis, wherein the optical module further comprises a first phase compensation unit located upstream of the optical path of the first phase delay unit. The optical module of the embodiment of the present invention can reduce the occurrence of light leakage in the folded optical path, and in particular, some preferred embodiments can reduce or eliminate light leakage in the folded optical path within a large angle range, which helps to improve the user's experience.

Description

Technical Field

[0001] The present invention generally relates to the field of optics, and more particularly to an optical module, a near-eye display device, and a light projection method. Background Art

[0002] In virtual display (VR), augmented display (AR), and other hybrid display technologies, optical modules are needed to present images to users. Existing optical modules are generally large in size, and the thickness is often more than 30 mm. With the advancement of technology, users pay more and more attention to the volume and weight of products. Therefore, it is necessary to develop a small and light product to meet market demand. Among them, the most limiting factor is the optical module. In order to solve the above-mentioned volume and weight problems, many companies have launched VR or AR solutions based on pancake technology solutions, that is, optical modules based on folded optical paths.

[0003] In this optical module with folded light path, it mainly includes a semi-reflective and semi-transmissive lens, a 1 / 4 phase delay plate and a reflective polarizer arranged in sequence. After the image source enters the semi-reflective and semi-transmissive lens, the light is folded back and forth between the lens, the phase delay plate and the reflective polarizer for many times, and finally emitted from the reflective polarizer. Through this optical solution, the product volume is greatly reduced.

[0004] However, in the current pancake solution, in addition to the light that the user expects, some unexpected light also enters the user's eyes, affecting the user experience. Especially when the incident angle of the light is large, the incident light will not necessarily be completely reflected when it passes through the reflective polarizer for the first time, but will produce a large proportion of light leakage. Part of the light will still pass through the reflective polarizer into the user's eyes. The intensity of the leakage light may reach 38% of the signal light intensity along the optical axis, thus affecting the user's viewing experience.

[0005] The contents of the background technology section are merely the technologies known to the public and do not necessarily represent the existing technologies in the field. Summary of the invention

[0006] In view of at least one problem of the prior art, the present invention provides an optical module, comprising:

[0007] A first phase delay unit, configured to modulate a light beam incident thereon into circular polarization or elliptically polarization;

[0008] a semi-transmissive and semi-reflective layer, located downstream of the optical path of the first phase delay unit and receiving the circularly polarized light or the elliptically polarized light;

[0009] A second phase delay unit is located downstream of the optical path of the semi-transmissive and semi-reflective layer; and

[0010] a polarization beam splitter, arranged downstream of the optical path of the second phase delay unit, the polarization beam splitter having a light transmission axis,

[0011] The optical module further includes a first phase compensation unit located upstream of the optical path of the first phase delay unit.

[0012] According to one aspect of the present invention, the optical module also includes a polarizer located upstream of the optical path of the first phase compensation unit, the polarizer receives the incident light beam and modulates it into linear polarized light, the first phase compensation unit receives the linear polarized light and modulates it to emit to the first phase delay unit.

[0013] According to one aspect of the present invention, the optical axis of the first phase compensation unit is located in a plane orthogonal to the light transmission axis of the polarizer, or in a plane orthogonal to the light absorption axis of the polarizer.

[0014] According to one aspect of the present invention, the first phase delay unit is configured to cause the polarization component of the linear polarized light incident thereon to produce a phase delay of n*pi+3 / 4pi or a phase delay of n*pi+1 / 4pi along the optical axis; the second phase delay unit is configured to cause the polarization component of the linear polarized light incident thereon to produce a phase delay of n*pi+3 / 4pi or a phase delay of n*pi+1 / 4pi along the optical axis, wherein n is an integer.

[0015] According to one aspect of the present invention, the light beam reflected by the polarization beam splitter is transmitted through the second phase delay unit, is partially reflected by the semi-transparent and semi-reflective layer, and is transmitted through the second phase delay unit again. The polarization direction of the returned light beam reaching the polarization beam splitter is parallel to the transmission axis of the polarization beam splitter.

[0016] According to one aspect of the present invention, the first phase delay unit and the second phase delay unit are both positive phase delay units or both negative phase delay units, and satisfy the following relationship:

[0017] α1=α2=45°or 135°,

[0018] α1 is the angle through which the light transmission axis of the polarizer rotates counterclockwise to the optical axis of the first phase delay unit when observed against the direction of the light path, and α2 is the angle through which the light transmission axis of the polarization beam splitter rotates counterclockwise to the optical axis of the second phase delay unit when observed against the direction of the light path.

[0019] According to one aspect of the present invention, the first phase delay unit and the second phase delay unit are positive phase delay units or negative phase delay units of opposite types, and satisfy the following relationship:

[0020] α1=-α2=45°or 135°,

[0021] α1 is the angle through which the light transmission axis of the polarizer rotates counterclockwise to the optical axis of the first phase delay unit when observed against the direction of the light path, and α2 is the angle through which the light transmission axis of the polarization beam splitter rotates counterclockwise to the optical axis of the second phase delay unit when observed against the direction of the light path.

[0022] According to one aspect of the present invention, the first phase compensation unit is configured to modulate the linear polarized light incident thereon from the polarizer in various directions according to its polarization state distribution, so that the polarization state of the light beam at each incident angle initially incident on the polarization beam splitter meets the condition of being reflected by the polarization beam splitter.

[0023] According to one aspect of the present invention, the optical module also includes a second phase compensation unit located between the second phase delay unit and the polarization beam splitter, and the optical axis of the second phase compensation unit is located in a plane orthogonal to the transmission axis of the polarization beam splitter, or in a plane orthogonal to the reflection axis of the polarization beam splitter.

[0024] According to one aspect of the present invention, the second phase compensation unit is configured such that: according to the polarization state distribution of the light beam at each incident angle that is initially incident on the second phase compensation unit, it is modulated so that the polarization state of the light beam at each incident angle that is initially incident on the second phase compensation unit after passing through the second phase compensation unit meets the condition of being reflected by the polarization splitter.

[0025] According to one aspect of the present invention, the optical module further comprises a lens, and the lens is disposed adjacent to the semi-transmissive and semi-reflective layer.

[0026] According to one aspect of the present invention, the semi-transmissive and semi-reflective layer is attached to the surface of the lens.

[0027] The present invention also provides a near-eye display device, comprising:

[0028] Display screen; and

[0029] The optical module as described above is arranged downstream of the light path of the display screen.

[0030] The present invention also provides a light projection method, comprising:

[0031] S101: receiving linearly polarized light through a first phase compensation unit, modulating the light and emitting the light;

[0032] S102: receiving a light beam from the first phase compensation unit through a first phase delay unit and modulating the light beam into circular polarization or elliptically polarization;

[0033] S103: receiving the circularly polarized light or the elliptically polarized light through a semi-transmissive and semi-reflective layer, and allowing the circularly polarized light or the elliptically polarized light to at least partially transmit;

[0034] S104: receiving the transmitted circularly polarized light or elliptically polarized light through a second phase delay unit and modulating and emitting the light; and

[0035] S105: Receive a light beam from the second phase delay unit through a polarization beam splitter, wherein the polarization beam splitter is arranged downstream in the optical path of the second phase delay unit, and the polarization beam splitter has a transmission axis, allowing a portion of the light beam whose polarization direction is parallel to the transmission axis of the polarization beam splitter to be transmitted, and reflecting the remaining portion of the light beam back to the second phase delay unit.

[0036] According to one aspect of the present invention, the light projection method also includes: generating linear polarized light through a polarizer, and the linear polarized light is incident on the first phase compensation unit, wherein the optical axis of the first phase compensation unit is located in a plane orthogonal to the transmission axis of the polarizer, or in a plane orthogonal to the absorption axis of the polarizer, and the first phase compensation unit is configured so that: the linear polarized light incident thereon from the polarizer in various directions is modulated according to its polarization state distribution, so that the polarization state of the light beam at each incident angle that is initially incident on the polarization splitter meets the condition of being reflected by the polarization splitter.

[0037] According to one aspect of the present invention, the light projection method further includes: modulating the light beam incident on the second phase compensation unit by a second phase compensation unit located between the second phase delay unit and the polarization beam splitter, wherein the optical axis of the second phase compensation unit is located in a plane orthogonal to the transmission axis of the polarization beam splitter, or in a plane orthogonal to the reflection axis of the polarization beam splitter, and the second phase compensation unit is configured such that: according to the polarization state distribution of the light beam initially incident on the second phase compensation unit, the light beam is modulated so that the polarization state of the light beam initially incident on the second phase compensation unit after passing through the second phase compensation unit meets the condition of being reflected by the polarization beam splitter.

[0038] According to one aspect of the present invention, the first phase delay unit and the second phase delay unit are both positive phase delay units or both negative phase delay units, and satisfy the following relationship: α1=α2=45° or 135°; or the first phase delay unit and the second phase delay unit are positive phase delay units or negative phase delay units of opposite types, and satisfy the following relationship: α1=-α2=45° or 135°,

[0039] Wherein α1 is the angle through which the light transmission axis of the polarizer rotates counterclockwise to the optical axis of the first phase delay unit when observed against the direction of the light path, and α2 is the angle through which the light transmission axis of the polarization beam splitter rotates counterclockwise to the optical axis of the second phase delay unit when observed against the direction of the light path.

[0040] According to one aspect of the present invention, the light projection method further comprises: the light beam reflected by the polarization beam splitter passes through the second phase delay unit and the semi-transmissive and semi-reflective layer and then returns, and the returned light beam emerges from the polarization beam splitter.

[0041] According to one aspect of the present invention, the light projection method is implemented by the optical module as described above.

[0042] The optical module of the embodiment of the present invention can reduce the occurrence of light leakage in the folded light path. In particular, some preferred embodiments can reduce or eliminate light leakage in the folded light path within a large angle range, which helps to improve the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0044] Figure 1 A schematic diagram of an optical module based on a folded optical path is shown;

[0045] Figure 2 A schematic diagram of an optical module according to an embodiment of the present invention is shown;

[0046] Figure 3 A schematic diagram of an optical module according to another embodiment of the present invention is shown;

[0047] Figure 4A , Figure 4B , Figure 4C and Figure 4D Schematic diagrams showing optical parameters of an optical module according to an embodiment of the present invention respectively;

[0048] Figure 5 A schematic diagram of an optical module according to Embodiment 1 of the present invention is shown;

[0049] Fig. 6A , 6B The polarization state changes of the light beam incident at a specific angle of the optical module according to Example 1 of the present invention are respectively shown;

[0050] Figure 6C and 6DThe distribution of the intensity of the signal light and the stray light of the optical module according to the first embodiment of the present invention with different incident angles of the light are respectively shown;

[0051] Figure 7 A schematic diagram of an optical module according to Embodiment 2 of the present invention is shown;

[0052] Fig. 8A shows the polarization state of the light beam of the optical module according to embodiment 2 of the present invention;

[0053] Figure 8B The figure shows the distribution of the intensity of the signal light and the stray light of the optical module according to the second embodiment of the present invention with different incident angles of the light;

[0054] Fig. 9 A schematic diagram of an optical module according to Embodiment 3 of the present invention is shown;

[0055] Fig. 10A shows the polarization state of the light beam of the optical module according to embodiment 3 of the present invention;

[0056] Fig. 10B shows the distribution of the intensity of the signal light and stray light of the optical module according to Embodiment 3 of the present invention with different incident angles of the light; and

[0057] Fig.11 A light projection method according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0058] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0059] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0060] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "sheet" and "film" should be understood in a broad sense, for example, it can be an independent optical element or a film layer attached to a lens or a transparent substrate.

[0062] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is lower in level than the second feature.

[0063] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0064] The embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0065] Figure 1 The optical module based on the folded optical path is shown in the figure. The right side of the figure is the object side, for example, where the display screen is placed, and the left side of the figure is the image side (observation side), that is, where the user's eyeball is located. Figure 1 In the optical module shown, along the direction of the light path (from the object side to the image side), a quarter wave plate 11, a semi-transmissive and semi-reflective layer 13 ( Figure 1 Attached to the lens 12), the quarter wave plate 14, and the polarization beam splitter 15. Theoretically, the light beam E1 (linear polarization) from the object side passes through the quarter wave plate 11, the lens 12, the semi-transparent and semi-reflective layer 13, and the quarter wave plate 14 in sequence, and then is incident on the polarization beam splitter 15. The light beam E3 that is first incident on the polarization beam splitter 15 is linear polarization, and its polarization direction is perpendicular to the transmission axis of the polarization beam splitter 15. Therefore, in theory, it should be reflected by the polarization beam splitter 15, and then be reflected by the semi-transparent and semi-reflective layer 13 after being transmitted through the quarter wave plate 14, and then pass through the quarter wave plate 14 again and be incident on the polarization beam splitter 15 again. At this time, the polarization direction of the polarized light E6 is parallel to the transmission axis of the polarization beam splitter 15, so it can be transmitted through the polarization beam splitter 15, as shown in FIG. Figure 1 However, in the actual folded light path, part of the light beam incident on the polarization beam splitter 15 for the first time will be transmitted through the polarization beam splitter 15, forming Figure 1 The "noise" shown is the light leakage phenomenon. Especially when the incident light beam is aligned with the optical axis OO ( Figure 1 When the incident angle formed by the axial signal (in the horizontal direction) is larger, the light leakage phenomenon is more serious, and the intensity of the leakage light (the intensity of the noise) can even reach 38% of the axial signal light intensity, seriously interfering with the user's viewing experience.

[0066] The inventor of the present application has found that the above problem can be solved by setting one or more phase compensation units in the optical path. And more preferably, it can be further improved by combining the parameter settings of some components in the optical module. The following is a detailed description.

[0067] Figure 2 An optical module 20 according to an embodiment of the present invention is shown. Figure 2 Describe in detail. Figure 2 As shown, the optical module 20 includes a polarizer Pol, a first phase delay unit QWP1, a semi-transparent and semi-reflective layer BS, a second phase delay unit QWP2, and a polarization splitter PBS along the optical path direction (from the object side to the image side, from right to left in the figure), and also includes a first phase compensation unit RA. The first phase compensation unit RA is located upstream of the optical path of the first phase delay unit QWP1, and is located between the first phase delay unit QWP1 and the polarizer Pol in the figure.

[0068] The polarizer Pol is configured to receive an incident light beam and modulate it into a linear polarized light E1, the first phase compensation unit RA receives the linear polarized light E1, and after modulation, emits it to the first phase delay unit QWP1. The first phase delay unit QWP1 is configured to modulate the light beam incident thereon into a circular polarized light or an elliptically polarized light. The semi-transmissive and semi-reflective layer BS is located downstream of the optical path of the first phase delay unit QWP1, and receives the circular polarized light or the elliptically polarized light, and partially transmits and partially reflects it. The second phase delay unit QWP2 is located downstream of the optical path of the semi-transmissive and semi-reflective layer BS, and a polarization beam splitter PBS is arranged downstream of the optical path of the second phase delay unit QWP2, and the polarization beam splitter PBS has a light transmission axis.

[0069] like Figure 2The working process of the optical module 20 shown is as follows. The polarizer Pol receives the incident light beam and emits linear polarization E1. After the linear polarization E1 passes through the first phase compensation unit RA, it emits linear polarization E1' with a certain circular polarization component, and then passes through the first phase delay unit QWP1 to be modulated into circular polarization or elliptically polarized light E2. The circular polarization or elliptically polarized light E2 is incident on the semi-transparent and semi-reflective layer BS. The semi-transparent and semi-reflective layer BS is located downstream of the optical path of the first phase delay unit QWP1, and receives the circular polarization or elliptically polarized light E2, allowing the circular polarization or elliptically polarized light to be at least partially transmitted. The present invention does not limit the specific transmittance of the semi-transparent and semi-reflective layer BS, which can be 50% or other proportions. The partially transmitted light beam is modulated into linear polarized light E3 through the second phase delay unit QWP2. The polarization direction of the linear polarized light E3 is perpendicular to the light transmission axis of the polarization beam splitter PBS, and is therefore reflected by the polarization beam splitter PBS. Then, the returned light beam is transmitted through the second phase delay unit QWP2 (circular polarized light or elliptically polarized light E4) and is reflected by the semi-transmissive and semi-reflective layer BS (circular polarized light or elliptically polarized light E5). It passes through the second phase delay unit QWP2 again (linear polarized light E6) and is incident on the polarization beam splitter PBS again. The polarization beam splitter PBS is arranged downstream of the optical path of the second phase delay unit QWP2, and the polarization beam splitter has a light transmission axis T PBS , allowing part of the light beam whose polarization direction is parallel to the transmission axis to be transmitted, and reflecting the rest of the light beam back to the second phase delay unit QWP2. At this time, the polarization direction of the polarized light E6 is parallel to the transmission axis of the polarization beam splitter PBS, so it can be transmitted through the polarization beam splitter PBS. That is, the light beam reflected by the polarization beam splitter PBS is transmitted through the second phase delay unit QWP2, partially reflected by the semi-transparent and semi-reflective layer BS, and transmitted through the second phase delay unit QWP2 again, and the polarization direction of the returned light beam reaching the polarization beam splitter PBS is parallel to the transmission axis of the polarization beam splitter PBS.

[0070] exist Figure 2 In the embodiment of the present invention, by adding a first phase compensation unit RA between the first phase delay unit QWP1 and the polarizer Pol, the polarization state of the light beam E3 at each incident angle initially incident on the polarization beam splitter PBS meets or tries to meet the condition of being reflected by the polarization beam splitter PBS, thereby greatly reducing the intensity of leakage light and stray light. The intensity of stray light can be reduced to 5% of the intensity of signal light, and the signal light will be basically not affected. Figure 2 The dot or arrow on the arrow used to indicate the light beam represents the polarization state of the light beam. Figure 2 The structure of the optical module 20 may not include the polarizer Pol. Meanwhile, the light beam incident on the first phase delay unit QWP1 may be linearly polarized light or linearly polarized light with a certain circular polarization component.

[0071] Compared to Figure 1 The optical structure of Figure 2 The optical module 20 includes a first phase compensation unit RA located between the first phase delay unit QWP1 and the polarizer Pol. According to a preferred embodiment of the present invention, the optical axis of the first phase compensation unit RA is located at a position parallel to the transmission axis T of the polarizer Pol. Pol In an orthogonal plane, or in a plane orthogonal to the absorption axis of the polarizer Pol. According to one embodiment of the present invention, the first phase compensation unit RA is configured so that: it is modulated according to the polarization state distribution of the linear polarized light incident thereon from the polarizer Pol in various directions, so that the polarization state of the light beam at each incident angle initially incident on the polarization beam splitter meets the condition of being reflected by the polarization beam splitter. It is easy for those skilled in the art to understand that in the present invention, the first phase compensation unit RA makes the polarization state of the light beam at each incident angle initially incident on the polarization beam splitter PBS meet the condition of being reflected by the polarization beam splitter, and it is not necessary to make the polarization state of the light beam initially incident on the polarization beam splitter completely meet the condition of being reflected, as long as the polarization state of a larger proportion of the light beam meets the condition of being reflected (compared with the case where no phase compensation unit is provided).

[0072] In addition, in the context of the present invention, "orthogonal" or "perpendicular" includes the situation of being 90 degrees to each other, but is not strictly limited to this. For example, within the range of 90°±5°, it can be considered as "orthogonal" or "perpendicular".

[0073] According to a preferred embodiment of the present invention, the first phase delay unit QWP1 is configured to cause the polarization component of the linear polarized light incident thereon to produce a phase delay of n*pi+3 / 4pi or a phase delay of n*pi+1 / 4pi along the optical axis; the second phase delay unit QWP2 is configured to cause the polarization component of the linear polarized light incident thereon to produce a phase delay of n*pi+3 / 4pi or a phase delay of n*pi+1 / 4pi along the optical axis, where n is an integer. According to a preferred embodiment of the present invention, the first phase delay unit QWP1 and the second phase delay unit QWP2 are both quarter wave plates.

[0074] In addition, preferably, in addition to providing the first phase compensation unit RA upstream of the optical path of the first phase delay unit QWP1, a second phase compensation unit RB may be provided between the second phase delay unit QWP2 and the polarization beam splitter PBS. Figure 3 An optical module 30 according to such an embodiment is shown. Figure 3The xyz coordinate system is also shown in the figure, wherein the positive x direction is perpendicular to the paper plane, the positive y direction is vertically downward, and the positive z direction (i.e., the direction along the optical path) is horizontally to the left (from the object side to the image side).

[0075] Preferably, the optical axis of the second phase compensation unit RB is located at the same position as the transmission axis T of the polarization beam splitter PBS. PBS In a plane orthogonal to the reflecting axis of the polarization beam splitter PBS.

[0076] The second phase compensation unit RB is configured to modulate the light beams at various incident angles that are initially incident on the second phase compensation unit RB according to their polarization state distribution, so that the polarization state of the light beams at various incident angles that are initially incident on the second phase compensation unit RB after passing through the second phase compensation unit RB meets the condition of being reflected by the polarization beam splitter. Figure 3 In an embodiment, the first phase compensation unit RA and the second phase compensation unit RB jointly compensate for the phase of the light beam, wherein the first phase compensation unit RA is configured to modulate the linear polarized light incident thereon from the polarizer Pol in various directions according to its polarization state distribution, and the second phase compensation unit RB is configured to modulate the light beam at each incident angle initially incident on the second phase compensation unit RB according to its polarization state distribution, so that the polarization state of the light beam initially incident on the polarization beam splitter PBS meets the condition of being reflected by the polarization beam splitter PBS.

[0077] exist Figure 2 and Figure 3 In the embodiment, the optical modules 20 and 30 both include the polarizer Pol, but the present invention is not limited thereto. The optical modules 20 and 30 may also not include the polarizer Pol. The polarizer Pol may be integrated with a light source (such as a screen) upstream of the optical path, for example. All of these are within the protection scope of the present invention.

[0078] It is easy for those skilled in the art to understand that the phase compensation amount of the first phase compensation unit RA and the second phase compensation unit RB is not limited to a specific value, as long as it can help to increase the proportion of the light beam reflected when it is first incident on the polarization beam splitter PBS. In addition, the first phase compensation unit RA and the second phase compensation unit can be composed of a single phase compensation plate, or can include multiple phase compensation plates, and the present invention does not limit the specific number. When performing a specific optical path design, after the wavelength, polarizer Pol, first phase delay unit QWP1, second phase delay unit QWP2, and optical parameters and device orientation parameters of PBS are given, the first phase compensation unit RA and the second phase compensation unit RB can be designed, as long as the proportion of the light beam reflected when it is first incident on the polarization beam splitter PBS can be increased compared to when the first phase compensation unit RA and the second phase compensation unit RB are not added. The specific calculation method will not be repeated here.

[0079] According to an embodiment of the present invention, the optical module further comprises a lens, and the lens is disposed adjacent to the semi-transmissive and semi-reflective layer BS. The semi-transmissive and semi-reflective layer BS may be attached to the surface of the lens, for example.

[0080] Further preferably, by setting the type of the first phase delay unit and the optical axis angle relationship, light leakage can be further eliminated or reduced. In order to clearly describe in the present invention, it is necessary to distinguish the "positive" and "negative" types of the first phase delay unit QWP1 and the second phase delay unit QWP2. "Positive" and "negative" are defined as follows:

[0081] Positive phase delay unit: causes the polarization component of the incident light beam along the optical axis to produce a phase delay of N*pi+1 / 4pi, where N is an integer;

[0082] Negative phase delay unit: causes the polarization component of the incident light beam along the optical axis to produce a phase delay of M*pi+3 / 4pi, where M is an integer.

[0083] According to a preferred embodiment of the present invention, when the following relationship is satisfied, Figure 1 The light leakage phenomenon shown can be further alleviated: the first phase delay unit QWP1 and the second phase delay unit QWP2 are both positive phase delay units or both negative phase delay units, and satisfy the following relationship: α1=α2=45° or 135°; or the first phase delay unit and the second phase delay unit are positive phase delay units or negative phase delay units of opposite types, and satisfy the following relationship: α1=-α2=45° or 135°,

[0084] Where α1 is observed against the direction of the light path (i.e. Figure 2 or Figure 3When the linear polarized light incident on the first phase delay unit QWP1 is incident normally, the polarization direction D1 rotates counterclockwise to the optical axis T of the first phase delay unit QWP1. QWP1 The angle of rotation is α2, which is the transmission axis T of the polarization beam splitter when viewed against the direction of the light path. PBS Rotate counterclockwise to the optical axis T of the second phase delay unit QWP2 QWP2 The angle of rotation. The relationship between the angles α1 and α2 is described above. It is easy for those skilled in the art to understand that the above equation allows errors within the acceptable range of engineering. For example, when the difference between the two and the target angle is within the range of plus or minus 5 degrees, the above equation can be considered to be satisfied. Taking the target angle α1=α2=45° as an example, when α1=40° and α2=50° in practice, it can be considered that α1=α2=45° is satisfied.

[0085] When the optical module includes a polarizer, the transmission axis of the polarizer is parallel to the polarization direction D1 of the linear polarized light incident on the first phase delay unit QWP1 when it is incident normally, so α1 is observed against the direction of the optical path (i.e., Figure 2 (viewed from left to right in the figure), the light transmission axis of the polarizer is rotated counterclockwise to the optical axis T of the first phase delay unit QWP1 QWP1 The angle of rotation.

[0086] Figure 4A The case where α1 is 45 degrees is shown. Figure 4B The case where α1 is 135 degrees is shown. Figure 4C The case where α2 is 45 degrees is shown. Figure 4D The case where α2 is 135 degrees is shown. When the light beam incident on the first phase delay unit QWP1 is linearly polarized, the polarization direction D1 is the polarization direction of the linear polarization. Or when a polarizer is provided upstream of the first phase delay unit QWP1, the polarization direction corresponds to the light transmission axis of the polarizer.

[0087] In the above embodiment, by adding the first phase compensation unit RA, the second phase compensation unit RB, and setting the types of the first phase delay unit QWP1 and the second phase delay unit QWP2 and the optical axis angle relationship, the polarization state of the light beam at each incident angle initially incident on the polarization beam splitter PBS can meet or meet as much as possible the condition of being reflected by the polarization beam splitter PBS, that is, the polarization direction is perpendicular to or as perpendicular as possible to the transmission axis T of the polarization beam splitter PBS. PBS , or parallel to or as parallel as possible to the reflecting axis of the polarization beam splitter PBS.

[0088] In addition, for the sake of clarity, the present invention will distinguish between a light beam that is incident on the polarization beam splitter for the first time and a light beam that is incident on the polarization beam splitter for the second time. Figure 2 , the light beam E1 passes through the first phase compensation unit RA, the first phase delay unit QWP1, the semi-transmissive and semi-reflective layer BS, and the second phase delay unit QWP2, and is modulated into the light beam E3 and incident on the polarization beam splitter PBS. The light beam E3 is called the light beam incident on the polarization beam splitter PBS for the first time; the light beam E6 is called the light beam incident on the polarization beam splitter for the second time, and the light beams E4, E5, and E6 can all be called return beams. The same understanding can be made for the optical path structures in the other figures, which will not be repeated here.

[0089] Compared with the folded light path solution of the prior art, the technical solution of the present invention can make the proportion of the light beam initially incident on the polarization beam splitter PBS transmitted through the polarization beam splitter PBS smaller, so the noise (stray light) generated is smaller. Most of the light beam is reflected and forms a folded light beam, and when it is incident on the polarization beam splitter PBS for the second time, its polarization direction is aligned with the transmission axis T of the polarization beam splitter PBS. PBS Parallel or as parallel as possible, so that it can transmit and form a signal (light).

[0090] The inventors tested the effects of the present invention through the following specific examples.

[0091] Example 1

[0092] The optical path structure of Example 1 is as follows Figure 5 As shown, there is a luminous screen upstream of the optical path of the absorbing polarizer Pol. The specific parameters of the optical path structure of Example 1 are as follows:

[0093] The transmission axis of the absorbing polarizer Pol is parallel to the x-axis; the first phase delay unit QWP1 is a positive phase delay unit, which consists of n o <n e The optical axis satisfies α1 = 45°, and the quarter wave plate is composed; the transmittance of the semi-transmissive and semi-reflective layer BS is 50%, and the reflectivity is 50%; the second phase delay unit QWP2 is a positive phase delay unit, which consists of n o <n e The quarter wave plate is formed with an optical axis satisfying α2=α1=45°; and the transmission axis of the polarization beam splitter PBS is parallel to the y-axis.

[0094] For the convenience of explanation, the polarization state of light during propagation is represented by a Pioncare sphere. The definition is as follows: θ is the angle between the light and the positive direction of the z axis, It is the angle between the projection of the light in the xy plane and the positive direction of the x-axis.

[0095] The intensity of signal light and stray light is distributed at different incident angles. Figure 6C , Fig.6D As shown in the figure, when the light angle θ is less than 30°, the intensity of the signal light is much greater than the intensity of the stray light, and the light leakage phenomenon in this area is not obvious.

[0096] Fig. 6A In Example 1, θ=60°, The polarization states of the incident light after first passing through the absorption polarizer Pol, the first phase delay unit QWP1, the second phase delay unit QWP2, and the polarization beam splitter PBS are represented by green dot M, magenta dot N, red dot 0, and black dot P, respectively. When incident: The rotation axis formed by the fast axis and slow axis of the first phase delay unit QWP1 is the magenta straight line F o S o The rotation axis formed by the fast axis and slow axis of QWP2 is the red straight line F N S N ,like Fig. 6A As shown; when the light is θ=60°, When incident, the polarization modulation process after it passes through the first phase delay unit QWP1 and the second phase delay unit QWP2 for the first time is expressed on the Poincare sphere as follows: QWP1 modulation process - point M is moved around the magenta straight line F N S N Rotate 90° clockwise to point N; QWP2 modulation process - move point N around the red straight line F o S o Rotate 90° clockwise to point 0. (Clockwise rotation means clockwise rotation when looking from end F to end S with respect to the straight line FS)

[0097] When the light is at θ = 60°, When incident, the polarization state that meets the reflection of the polarization beam splitter PBS is the point symmetrical about the center of the sphere (coincides with the green point M at this time) on the Pioncare sphere, and Fig. 6A It can be seen that with θ = 60°, After the incident light passes through the absorption polarizer Pol, the first phase delay unit QWP1, and the second phase delay unit QWP2 for the first time, the polarization state (red point 0) does not coincide with the green point M, and the angle formed by the radii at the two points is large. Therefore, the light that first reaches the polarization beam splitter PBS will not be completely absorbed, and a certain degree of light leakage will occur.

[0098] Figure 6B In Example 1, θ=60°, The polarization states of the incident light after first passing through the absorption polarizer Pol, the first phase delay unit QWP1, the second phase delay unit QWP2, and the polarization beam splitter PBS are represented by green dot M, magenta dot N, red dot 0, and black dot P, respectively. The light is θ = 60°, When incident, the polarization state reflected by PBS is the point symmetrical about the center of the sphere as the black point P on the Pioncare sphere, and Figure 6B It can be seen that with θ = 60°, After the incident light passes through the polarizer, the first phase delay unit QWP1, and the second phase delay unit QWP2 for the first time, the polarization state does not coincide with the symmetric point of point P about the center of the sphere, and the angle formed by the radii at the two points is large. Therefore, a part of the light that first reaches the polarization beam splitter PBS will directly pass through the polarization beam splitter PBS instead of being completely reflected, and a certain degree of light leakage will occur.

[0099] According to the scheme of embodiment 1, when θ is large, the intensity of stray light is comparable to the intensity of signal light, especially when θ=65°, There is a certain amount of light leakage nearby.

[0100] Example 2

[0101] Compared with the embodiment 1, the optical path structure of the embodiment 2 has the following difference: a first phase compensation unit RA is added. Figure 7 shown.

[0102] The second phase delay unit is a negative phase delay unit, which consists of n o >n e The optical axis is formed by a quarter wave plate satisfying α2 = -α1 = -45° (ie 135°). The first phase delay unit is a positive phase delay unit.

[0103] The first phase compensation RA can have multiple configurations. The parameters of the first phase compensation unit RA selected in this embodiment are shown in the following table, which includes a phase delay plate A1 and a phase delay plate A2 superimposed along the optical path direction. The parameters of the phase delay plate A1 are as follows: o <n e , the optical axis is parallel to the x-axis, and the phase delay is 100nm. The parameters of the phase delay plate A2 are as follows: n o >n e , the optical axis is parallel to the y-axis and the phase delay is 101nm.

[0104] Phase Retardation Plate A1 Phase Retardation Plate A2 Optical axis direction Parallel to the x-axis Parallel to the y-axis Retardance 100nm 101nm type <![CDATA[n o <n e ]]> <![CDATA[n o >n e ]]>

[0105] Still Taking the incident light as an example, the polarization state changes in the structure of Example 2 are as follows: Fig. 8A As shown, it can be seen that the polarization state point O of the light passing through the second phase delay unit QWP2 for the first time is very close to the symmetric point P about the center of the sphere, so most of the light is reflected when entering the polarization beam splitter PBS for the first time, and the light leakage is reduced.

[0106] The intensity of stray light is distributed at different incident angles. Figure 8B As shown. Fig.6D In comparison, this embodiment greatly reduces light leakage in the folded light path, and the light leakage intensity is reduced to 12% of the original.

[0107] Example 3

[0108] Fig. 9 The optical path structure of embodiment 3 is shown. Compared with embodiment 1, the optical path structure of embodiment 3 has the following differences: a first phase compensation unit RA and a second phase compensation unit RB are added.

[0109] The second phase delay unit is a negative phase delay unit, which consists of n o >n e The optical axis is formed by a quarter wave plate satisfying α2=-α1=-45°. The first phase delay unit is a positive phase compensation unit.

[0110] The first phase compensation unit RA can have a variety of configurations. The parameters of the first phase compensation unit RA selected in this embodiment are as follows: it includes a phase delay plate A1 and a phase delay plate A2 superimposed along the optical path direction. The parameters of the phase delay plate A1 are as follows: n o <n e , the optical axis is parallel to the x-axis, and the phase delay is 206nm. The parameters of the phase delay plate A2 are as follows: n o <n e , the optical axis is parallel to the y-axis and the phase delay is 85nm.

[0111] Phase Retardation Plate A1 Phase Retardation Plate A2 Optical axis direction Parallel to the x-axis Parallel to the y-axis Retardance 206nm 85nm type <![CDATA[n o <n e ]]> <![CDATA[n o >n e ]]>

[0112] The second phase compensation unit RB can have a variety of configurations. The parameters of the second phase compensation unit RB selected in this embodiment are as follows: it includes a phase delay plate B1 and a phase delay plate B2 superimposed along the optical path direction. The parameters of the phase delay plate B1 are as follows: n o >n e , the optical axis is parallel to the x-axis, and the phase delay is 85nm. The parameters of the phase delay plate B2 are as follows: n o >n e , the optical axis is parallel to the y-axis and the phase delay is 206nm.

[0113] Phase Retardation Plate B1 Phase Retardation Plate B2 Optical axis direction Parallel to the x-axis Parallel to the y-axis Retardance 85nm 206nm type <![CDATA[n o >n e ]]> <![CDATA[n o >n e ]]>

[0114] by The polarization state of the incident light in the structure of Example 3 changes as follows: Fig. 10A As shown, it can be seen that the polarization state point V of the light passing through the second phase compensation unit for the first time is almost coincident with the symmetric point P about the center of the sphere, so the light is almost completely reflected when entering the polarization beam splitter PBS for the first time, and no light leakage occurs.

[0115] The intensity of stray light is distributed at different incident angles. Fig. 10B As shown. Figure 8B In comparison, this embodiment greatly reduces light leakage in the folded light path, and the light leakage intensity is reduced to 7% of the original.

[0116] It can be seen from the above-mentioned embodiments 1-3 that the optical module according to the embodiment of the present invention can reduce the occurrence of light leakage in the folded light path.

[0117] The present invention also relates to a near-eye display device, comprising: a display screen; and the optical module 20 or 30 as described above, the optical module 20 or 30 being arranged downstream of the optical path of the display screen. The near-eye display device is such as an augmented reality (AR) device, a virtual reality (VR) device, or other types of mixed reality (MR) devices.

[0118] Fig.11 A light projection method 100 according to an embodiment of the present invention is shown. Fig.11 Detailed description.

[0119] In step S101: linear polarization light is received by a first phase compensation unit, and modulated to emit the linear polarization light;

[0120] In step S102: receiving a light beam from the first phase compensation unit through a first phase delay unit and modulating the light beam into circular polarization or elliptically polarization;

[0121] In step S103: receiving the circularly polarized light or the elliptically polarized light through the semi-transmissive and semi-reflective layer, and allowing the circularly polarized light or the elliptically polarized light to at least partially transmit;

[0122] In step S104: receiving the transmitted circularly polarized light or elliptically polarized light through a second phase delay unit and modulating and emitting the light; and

[0123] In step S105: a light beam is received from the second phase delay unit through a polarization beam splitter, wherein the polarization beam splitter is arranged downstream in the optical path of the second phase delay unit, and the polarization beam splitter has a transmission axis, allowing a portion of the light beam whose polarization direction is parallel to the transmission axis of the polarization beam splitter to be transmitted, and reflecting the remaining portion of the light beam back to the second phase delay unit.

[0124] According to one aspect of the present invention, the light projection method also includes: generating linear polarized light through a polarizer, and the linear polarized light is incident on the first phase compensation unit, wherein the optical axis of the first phase compensation unit is located in a plane orthogonal to the transmission axis of the polarizer, or in a plane orthogonal to the absorption axis of the polarizer, and the first phase compensation unit is configured so that: the linear polarized light incident thereon from the polarizer in various directions is modulated according to its polarization state distribution, so that the polarization state of the light beam at each incident angle that is initially incident on the polarization splitter meets the condition of being reflected by the polarization splitter.

[0125] According to one aspect of the present invention, the light projection method further includes: modulating the light beam incident on the second phase compensation unit by a second phase compensation unit located between the second phase delay unit and the polarization beam splitter, wherein the optical axis of the second phase compensation unit is located in a plane orthogonal to the transmission axis of the polarization beam splitter, or in a plane orthogonal to the reflection axis of the polarization beam splitter, and the second phase compensation unit is configured such that: according to the polarization state distribution of the light beam initially incident on the second phase compensation unit, the light beam is modulated so that the polarization state of the light beam initially incident on the second phase compensation unit after passing through the second phase compensation unit meets the condition of being reflected by the polarization beam splitter.

[0126] According to one aspect of the present invention, the first phase delay unit and the second phase delay unit are both positive phase delay units or both negative phase delay units, and satisfy the following relationship: α1=α2=45° or Or the first phase delay unit and the second phase delay unit are positive phase delay units or negative phase delay units of opposite types, and satisfy the following relationship: α1=-α2=45° or 135°,

[0127] Wherein α1 is the angle through which the light transmission axis of the polarizer rotates counterclockwise to the optical axis of the first phase delay unit when observed against the direction of the light path, and α2 is the angle through which the light transmission axis of the polarization beam splitter rotates counterclockwise to the optical axis of the second phase delay unit when observed against the direction of the light path.

[0128] According to one aspect of the present invention, the light projection method further comprises: the light beam reflected by the polarization beam splitter passes through the second phase delay unit and the semi-transmissive and semi-reflective layer and then returns, and the returned light beam emerges from the polarization beam splitter.

[0129] According to one aspect of the present invention, the light projection method is implemented by the optical module 20 or 30 as described above.

[0130] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An optical module, comprising: A first phase delay unit, configured to modulate a light beam incident thereon into circular polarization or elliptically polarization; a semi-transmissive and semi-reflective layer, located downstream of the optical path of the first phase delay unit and receiving the circularly polarized light or the elliptically polarized light; A second phase delay unit is located downstream of the optical path of the semi-transmissive and semi-reflective layer; and a polarization beam splitter, arranged downstream of the optical path of the second phase delay unit, the polarization beam splitter having a light transmission axis, The optical module further includes a first phase compensation unit located upstream of the optical path of the first phase delay unit, and the first phase compensation unit is configured to modulate the linear polarized light according to its polarization state distribution incident thereon in various directions, so that the polarization state of the light beam at each incident angle that is initially incident on the polarization beam splitter meets the condition of being reflected by the polarization beam splitter.

2. The optical module as described in claim 1 further includes a polarizer located upstream of the optical path of the first phase compensation unit, the polarizer receives the incident light beam and modulates it into linear polarized light, the first phase compensation unit receives the linear polarized light and modulates it to emit it to the first phase delay unit. 3 . The optical module as claimed in claim 2 , wherein the optical axis of the first phase compensation unit is located in a plane orthogonal to the light transmission axis of the polarizer, or in a plane orthogonal to the light absorption axis of the polarizer.

4. An optical module as described in any one of claims 1-3, wherein the first phase delay unit is configured to cause the polarization component of the linear polarized light incident thereon to produce a phase delay of n*pi+3 / 4pi or a phase delay of n*pi+1 / 4pi along the optical axis; the second phase delay unit is configured to cause the polarization component of the linear polarized light incident thereon to produce a phase delay of n*pi+3 / 4pi or a phase delay of n*pi+1 / 4pi along the optical axis, wherein n is an integer.

5. An optical module as described in any one of claims 1-3, wherein the light beam reflected by the polarization beam splitter is transmitted through the second phase delay unit, is partially reflected by the semi-transparent and semi-reflective layer, and is transmitted through the second phase delay unit again, and the polarization direction of the returned light beam reaching the polarization beam splitter is parallel to the transmission axis of the polarization beam splitter.

6. The optical module according to claim 2, wherein the first phase delay unit and the second phase delay unit are both positive phase delay units or both negative phase delay units, and satisfy the following relationship: ， The angle through which the light transmission axis of the polarizer rotates counterclockwise to the optical axis of the first phase delay unit when observing against the direction of the light path. The angle through which the light transmission axis of the polarization beam splitter rotates counterclockwise to the optical axis of the second phase delay unit when observed against the direction of the light path.

7. The optical module according to claim 2, wherein the first phase delay unit and the second phase delay unit are positive phase delay units or negative phase delay units of opposite types, and satisfy the following relationship: ， The angle through which the light transmission axis of the polarizer rotates counterclockwise to the optical axis of the first phase delay unit when observing against the direction of the light path. The angle through which the light transmission axis of the polarization beam splitter rotates counterclockwise to the optical axis of the second phase delay unit when observed against the direction of the light path.

8. The optical module as described in claim 1 further includes a second phase compensation unit located between the second phase delay unit and the polarization beam splitter, and the optical axis of the second phase compensation unit is located in a plane orthogonal to the transmission axis of the polarization beam splitter, or in a plane orthogonal to the reflection axis of the polarization beam splitter.

9. An optical module as described in claim 8, wherein the second phase compensation unit is configured such that: according to the polarization state distribution of the light beam at each incident angle that is initially incident on the second phase compensation unit, it is modulated so that the polarization state of the light beam at each incident angle that is initially incident on the second phase compensation unit after passing through the second phase compensation unit meets the condition of being reflected by the polarization splitter.

10. The optical module according to any one of claims 1 to 3, further comprising a lens, wherein the lens is disposed adjacent to the semi-transmissive and semi-reflective layer. The optical module as claimed in claim 10 , wherein the semi-transmissive and semi-reflective layer is attached to the surface of the lens.

12. A near-eye display device, comprising: Display screen; and The optical module according to any one of claims 1 to 11 is arranged downstream of the light path of the display screen.

13. A light projection method, comprising: S101: receiving linearly polarized light through a first phase compensation unit, modulating the light and emitting the light; S102: receiving a light beam from the first phase compensation unit through a first phase delay unit and modulating the light beam into circular polarization or elliptically polarization; S103: receiving the circularly polarized light or the elliptically polarized light through a semi-transmissive and semi-reflective layer, and allowing the circularly polarized light or the elliptically polarized light to at least partially transmit; S104: receiving the transmitted circularly polarized light or elliptically polarized light through a second phase delay unit and modulating and emitting the light; and S105: receiving a light beam from the second phase delay unit through a polarization beam splitter, wherein the polarization beam splitter is arranged downstream of the light path of the second phase delay unit, the polarization beam splitter has a light transmission axis, allows a portion of the light beam whose polarization direction is parallel to the light transmission axis of the polarization beam splitter to be transmitted, and reflects the remaining portion of the light beam back to the second phase delay unit, The first phase compensation unit is configured to modulate the linear polarized light incident thereon in various directions according to its polarization state distribution, so that the polarization state of the light beam at each incident angle initially incident on the polarization beam splitter meets the condition of being reflected by the polarization beam splitter.

14. The light projection method according to claim 13, further comprising: Linear polarized light is generated by a polarizer and incident on the first phase compensation unit, wherein the optical axis of the first phase compensation unit is located in a plane orthogonal to the light transmission axis of the polarizer or in a plane orthogonal to the light absorption axis of the polarizer.

15. The light projection method according to claim 13, further comprising: The light beam incident on the second phase compensation unit is modulated by a second phase compensation unit located between the second phase delay unit and the polarization beam splitter, wherein the optical axis of the second phase compensation unit is located in a plane orthogonal to the transmission axis of the polarization beam splitter, or in a plane orthogonal to the reflection axis of the polarization beam splitter, and the second phase compensation unit is configured so that: according to the polarization state distribution of the light beam initially incident on the second phase compensation unit, it is modulated so that the polarization state of the light beam initially incident on the second phase compensation unit after passing through the second phase compensation unit meets the condition of being reflected by the polarization beam splitter.

16. The light projection method according to claim 14, wherein the first phase delay unit and the second phase delay unit are both positive phase delay units or both negative phase delay units, and satisfy the following relationship: ; or the first phase delay unit and the second phase delay unit are positive phase delay units or negative phase delay units of opposite types, and satisfy the following relationship: , in The angle through which the light transmission axis of the polarizer rotates counterclockwise to the optical axis of the first phase delay unit when observing against the direction of the light path. The angle through which the light transmission axis of the polarization beam splitter rotates counterclockwise to the optical axis of the second phase delay unit when observed against the direction of the light path.

17. The light projection method according to any one of claims 13 to 15, further comprising: The light beam reflected by the polarization beam splitter is folded back after passing through the second phase delay unit and the semi-transmissive and semi-reflective layer, and the folded light beam is emitted from the polarization beam splitter.

18. The light projection method according to any one of claims 13 to 15, wherein the light projection method is implemented by an optical module according to any one of claims 1 to 11.

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