Polarization-maintaining film, total reflection polarization-maintaining prism, and method for realizing total reflection polarization-maintaining

Abstract

The present invention relates to a polarization-maintaining film for a total reflection prism, which is stacked by a SiO2 film layer with a thickness of 81.3-85.4 nm and a refractive index of 1.46 and a TiO2 film layer with a thickness of 73.4-77.7 nm and a refractive index of 2.4, and the SiO2 film layer is an inner layer close to the total reflection surface of the total reflection prism, and the TiO2 film layer is an outer layer. The invention scheme adopts the total reflection principle of the total reflection prism to eliminate reflection loss and achieve the effect of 100% reflectivity; the invention scheme adopts the total reflection principle of the total reflection prism to eliminate the polarization-related loss of reflected light, so that the reflectivity of P polarized light and S polarized light is equal.

Description

Technical Field

[0001] The invention relates to the field of optics, and in particular to a polarization-maintaining film, a total reflection polarization-maintaining prism and a method for realizing total reflection polarization-maintaining. Background Art

[0002] The reflector in the optical system will change the polarization state of the incident light to a certain extent, that is, residual polarization will be generated, which will reduce the imaging ability of the optical system. Therefore, in some optical reflection systems, residual polarization should be avoided or reduced so that the polarization state of the incident light remains unchanged after reflection, that is, the use of polarization-maintaining reflectors is required. Polarization-maintaining reflection is equivalent to no phase delay of the light beam after passing through the reflector, and the intensity of P-polarized light and S-polarized light remains consistent.

[0003] General optical reflection displacement devices, such as corner cube prisms and right-angle prisms, realize light beam reversal based on the principle of total reflection of light beam from optically dense medium to optically sparse medium. However, due to the influence of total reflection on the phase loss of light beam, the polarization state of the reflected light beam changes compared with the incident light beam, making it impossible to use it in applications that require polarization-maintaining characteristics. Summary of the invention

[0004] The present invention provides a polarization-maintaining film, a total reflection polarization-maintaining prism and a method for realizing total reflection polarization-maintaining. The polarization-maintaining film can be plated or adhered to the total reflection surface of the total reflection prism to form a total reflection polarization-maintaining prism. When the total reflection polarization-maintaining prism and the method for realizing total reflection polarization-maintaining are used, when light is reflected, as long as the incident angle of the light incident on the total reflection surface of the total reflection prism through the total reflection prism is greater than the total reflection angle, the reflected light will not be phase delayed, and the intensities of P polarized light and S polarized light remain consistent, so the influence of reflection on the polarization state of the light beam can be eliminated, and the effect of reflection polarization-maintaining can be realized.

[0005] Solution 1

[0006] A polarization-maintaining film for a total reflection prism is formed by stacking a SiO2 film layer with a thickness of 81.3-85.4 nm and a refractive index of 1.46 and a TiO2 film layer with a thickness of 73.4-77.7 nm and a refractive index of 2.4, wherein the SiO2 film layer is an inner layer close to the total reflection surface of the total reflection prism, and the TiO2 film layer is an outer layer.

[0007] Preferably, the SiO2 film layer is composed of a SiO2 film layer with a thickness of 81.3 nm and a refractive index of n=1.46, and the TiO2 film layer is composed of a TiO2 film layer with a thickness of 73.4 nm and a refractive index of n=2.4.

[0008] Preferably, the thickness of the SiO2 film layer is 85.4 nm, and the thickness of the TiO2 film layer is 77.7 nm.

[0009] Solution 2

[0010] A total reflection polarization-maintaining prism comprises a right-angled triangular prism, wherein the prism surface of the right-angled triangular prism consists of an inclined plane and a first right-angled plane and a second right-angled plane respectively connected to two sides of the inclined plane and perpendicular to each other, wherein one of the right-angled planes is a light incident plane of the right-angled triangular prism, the inclined plane is a total reflection plane of the right-angled triangular prism, and the other right-angled plane is a light emitting plane of the right-angled triangular prism; and a polarization-maintaining film as described in scheme 1 is arranged on the outer side of the inclined plane of the right-angled triangular prism.

[0011] Preferably, in order to increase the transmittance of the light used in the right-angled triangular prism, anti-reflection film layers are provided on both right-angled faces of the right-angled triangular prism.

[0012] Preferably, the right-angled triangular prism is an isosceles right-angled prism.

[0013] Preferably, the right-angled triangular prism is made of a light-transmissive glass material.

[0014] Further preferably, the material used for the right-angle triangular prism is K9 glass with a refractive index n=1.52.

[0015] Option 3

[0016] A method for achieving total reflection and polarization maintenance, characterized in that: a polarization-maintaining film as described in scheme one is provided on the surface of a total reflection prism used as a total reflection surface, and light is made to pass through the total reflection prism and be incident on the total reflection surface of the total reflection prism at an incident angle greater than the total reflection angle of the total reflection prism.

[0017] Preferably, the total reflection prism is a right-angle triangular prism, the SiO2 film layer is composed of a SiO2 film layer with a thickness of 81.3nm and a refractive index of n=1.46, the TiO2 film layer is composed of a TiO2 film layer with a thickness of 73.4nm and a refractive index of n=2.4, and the material used in the right-angle triangular prism is K9 glass with a refractive index of n=1.52, so that light passes through the total reflection prism at an incident angle of 45 degrees and is incident on the total reflection surface of the total reflection prism. The total reflection angle of the total reflection prism of the K9 material is 42 degrees, so the incident angle of the light from the glass to the air is greater than the total reflection angle of 42° and less than 90°.

[0018] Alternatively, preferably, the total reflection prism is a right-angle triangular prism, the SiO2 film layer is composed of a SiO2 film layer with a thickness of 85.4nm and a refractive index n=1.46, the TiO2 film layer is composed of a TiO2 film layer with a thickness of 77.7nm and a refractive index n=2.4, and the material used for the right-angle triangular prism is K9 glass with a refractive index n=1.52, so that light passes through the total reflection prism at an incident angle of 45 degrees and is incident on the total reflection surface of the total reflection prism.

[0019] Preferably, the right-angle prism is an isosceles right-angle prism.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The invention adopts the total reflection principle of the total reflection prism to eliminate reflection loss and achieve a 100% reflectivity effect;

[0022] (2) The invention scheme adopts the total reflection principle of the total reflection prism to eliminate the polarization-related loss of the reflected light, so that the reflectivity of the P-polarized light and the S-polarized light are equal;

[0023] (3) The invention adopts a polarization-maintaining film to solve the problem of reflection phase loss, eliminates the influence of reflection on the polarization state of the light beam, and achieves the effect of reflection polarization-maintaining;

[0024] (4) The polarization-maintaining film of the invention can achieve a phase difference of 0 degree after reflection, and right-handed circularly polarized light remains right-handed circularly polarized light after reflection.

[0025] (5) The polarization-maintaining film of the invention can be coated on one surface of the prism to achieve beam deflection, or can be coated on both surfaces of the prism to achieve beam return;

[0026] (6) The invention scheme is not sensitive to small angle position errors or processing size errors of the prism. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the geometric structure and optical path of the present invention.

[0028] Figure 2 This is a reflectance characteristic diagram of the present invention (Example 1).

[0029] Figure 3 This is a characteristic diagram of the reflected light phase change of Example 1 of the present invention.

[0030] Figure 4 This is a characteristic diagram of the reflected light phase change of Example 2 of the present invention.

[0031] Figure 5 This is a characteristic diagram of the reflected light phase change of Example 3 of the present invention. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments:

[0033] Embodiment 1:

[0034] A polarization-maintaining film for a total reflection prism is formed by stacking a SiO2 film layer with a thickness of 81.3 nm and a refractive index of 1.46 and a TiO2 film layer with a thickness of 73.4 nm and a refractive index of 2.4, wherein the SiO2 film layer is an inner layer close to the total reflection surface of the total reflection prism, and the TiO2 film layer is an outer layer.

[0035] A total reflection polarization-maintaining prism comprises a right-angled triangular prism, wherein the prism surface of the right-angled triangular prism consists of an inclined plane 1 and a first right-angled plane 2 and a second right-angled plane 3 respectively connected to two sides of the inclined plane 1 and perpendicularly connected to each other, wherein one of the right-angled planes is a light incident plane of the right-angled triangular prism, the inclined plane 1 is a total reflection plane of the right-angled triangular prism, and the other right-angled plane is a light emitting plane of the right-angled triangular prism; and a polarization-maintaining film 4 described in this embodiment is arranged on the outer side of the inclined plane 1 of the right-angled triangular prism.

[0036] In this embodiment, in order to increase the transmittance of the light used in the right-angled triangular prism, both right-angled surfaces of the right-angled triangular prism are provided with anti-reflection film layers. Alternatively, no anti-reflection film layer is provided.

[0037] The right-angled triangular prism described in this embodiment is an isosceles right-angled prism.

[0038] The material used for the right-angle triangular prism is a glass material through which light can pass.

[0039] The material used for the right-angled triangular prism described in this embodiment is K9 glass with a refractive index n=1.52.

[0040] A method for achieving total reflection and polarization maintenance, wherein the polarization maintaining film described in this embodiment is provided on the surface of a total reflection prism used as a total reflection surface, and light is incident on the total reflection surface of the total reflection prism through the total reflection prism at an incident angle greater than the total reflection angle of the total reflection prism. The right-angle prism of this embodiment adopts K9 glass with a refractive index n=1.52. The total reflection angle of the total reflection prism of the K9 material is 42 degrees, so the incident angle of the light from the glass to the air is greater than 42 degrees. According to the principle of total reflection, the total reflection angle = arcsin(n1 / n2), where n1 is the refractive index of the optically sparse medium and n2 is the refractive index of the optically dense medium; therefore, the total reflection angle of K9 to air = 42 degrees. Figure 1 The light shown is incident from the right angle face of the right triangle prism and reflected from the inclined face.

[0041] Because the SiO2 film layer described in this embodiment is composed of a SiO2 film layer with a thickness of 81.3nm and a refractive index of n=1.46, and the TiO2 film layer is composed of a TiO2 film layer with a thickness of 73.4nm and a refractive index of n=2.4, and the material used for the right-angle triangular prism is K9 glass with a refractive index of n=1.52, the light passes through the total reflection prism at an incident angle of 45 degrees and is incident on the total reflection surface of the total reflection prism.

[0042] In this embodiment, a circularly polarized laser with a wavelength of 633 nm is incident on the right-angle prism for polarization-maintaining reflection:

[0043] like Figure 2 As shown, it is a reflectivity characteristic diagram of the present invention. It can be seen from the figure that the total reflection polarization-maintaining prism provided by the present invention can fully reflect the P polarization state and S polarization state of the 633nm circularly polarized laser 100%, that is, Rs=Rp=100%@633nm.

[0044] like Figure 3 As shown in the figure, it is a characteristic diagram of the phase change of the reflected light of the present invention. It can be seen from the figure that the total reflection polarization-maintaining prism provided by the present invention can make the phase difference between the two polarization states of the 633nm laser be 0 degree (or 360 degrees) after total reflection. Assuming that the 633nm laser is right-handed circularly polarized light, it is still right-handed circularly polarized light after being reflected by the prism of the present invention; and vice versa.

[0045] Example 2

[0046] Different from the above-mentioned embodiment 1, the SiO2 film layer described in this embodiment is composed of a SiO2 film layer with a thickness of 85.4nm and a refractive index n=1.46, the TiO2 film layer is composed of a TiO2 film layer with a thickness of 77.7nm and a refractive index n=2.4, and the material used for the right-angle triangular prism is K9 glass with a refractive index n=1.52, so that light passes through the total reflection prism at an incident angle of 45 degrees and is incident on the total reflection surface of the total reflection prism. A laser with a wavelength of 405nm is used for incident.

[0047] like Figure 4 As shown in the figure, it is a characteristic diagram of the phase change of the reflected light of the present invention. It can be seen from the figure that the total reflection polarization-maintaining prism provided by the present invention can make the phase difference between the two polarization states of the 405nm laser be 0 degree (or 360 degrees) after total reflection. Assuming that the 405nm laser is right-handed circularly polarized light, it is still right-handed circularly polarized light after being reflected by the prism of the present invention; and vice versa.

[0048] Example 3

[0049] Different from the above-mentioned embodiment 1, the SiO2 film layer described in this embodiment is composed of a SiO2 film layer with a thickness of 85.4nm and a refractive index of n=1.46, the TiO2 film layer is composed of a TiO2 film layer with a thickness of 77.7nm and a refractive index of n=2.4, and the material used for the right-angle triangular prism is K9 glass with a refractive index of n=1.52, so that light passes through the total reflection prism at an incident angle of 45 degrees and is incident on the total reflection surface of the total reflection prism. A laser with a wavelength of 1064nm is used for incident.

[0050] like Figure 5 As shown in the figure, it is a characteristic diagram of the phase change of the reflected light of the present invention. It can be seen from the figure that the total reflection polarization-maintaining prism provided by the present invention can make the phase difference between the two polarization states of the 1064nm laser be 0 degree (or 360 degrees) after total reflection. Assuming that the 1064nm laser is right-handed circularly polarized light, it is still right-handed circularly polarized light after being reflected by the prism of the present invention; and vice versa.

[0051] For 0 degree phase difference: the phase difference between the two polarization states of the laser after a single total reflection is 0 degree, the polarization state of the laser remains unchanged and is still circularly polarized, and the rotation direction of the circularly polarized light remains unchanged.

[0052] The above specific implementation modes are only detailed explanations of the technical solutions of the present invention. The present invention is not limited to the above embodiments. Any improvement or replacement based on the principles of the present invention should be within the protection scope of the present invention.

Claims

1. A polarization-maintaining film for a total reflection prism, characterized in that: It is composed of two stacked film layers, one of which is a SiO2 film layer with a thickness of 81.3-85.4nm and a refractive index of 1.46, and the other is a TiO2 film layer with a thickness of 73.4-77.7nm and a refractive index of 2.4, and the SiO2 film layer is the inner layer close to the total reflection surface of the total reflection prism, and the TiO2 film layer is the outer layer; The phase difference between the P polarized light and the S polarized light during reflection by the polarization-maintaining film used in the total reflection prism is 0° or 360°.

2. The polarization-maintaining film according to claim 1, characterized in that: The thickness of the SiO2 film layer is 85.4 nm, and the thickness of the TiO2 film layer is 77.7 nm.

3. The polarization-maintaining film according to claim 1, characterized in that: The thickness of the SiO2 film layer is 81.3 nm, and the thickness of the TiO2 film layer is 73.4 nm.

4. A total reflection polarization-maintaining prism, characterized in that: It comprises a right-angle triangular prism, wherein the prism surface of the right-angle triangular prism consists of an inclined surface (1), a first right-angle surface (2) and a second right-angle surface (3) respectively connected to the two sides of the inclined surface (1) and perpendicularly connected to each other, wherein one of the right-angle surfaces is the light incident surface of the right-angle triangular prism, the inclined surface (1) is the total reflection surface of the right-angle triangular prism, and the other right-angle surface is the light exit surface of the right-angle triangular prism; and a polarization-maintaining film (4) as claimed in claim 1, 2 or 3 is provided on the outer side of the inclined surface (1) of the right-angle triangular prism.

5. The total reflection polarization-maintaining prism according to claim 4, characterized in that: Anti-reflection film layers are arranged on the two right-angled surfaces of the right-angle triangular prism.

6. The total reflection polarization-maintaining prism according to claim 4, characterized in that: The right-angled triangular prism is an isosceles right-angled prism.

7. The total reflection polarization-maintaining prism according to claim 4, characterized in that: The material used for the right-angle triangular prism is a glass material through which light can pass.

8. The total reflection polarization-maintaining prism according to claim 7, characterized in that: The material used for the right-angle triangular prism is K9 glass with a refractive index n=1.

52.

9. A method for achieving total reflection polarization maintenance, characterized in that: A polarization-maintaining film as claimed in claim 1, 2 or 3 is provided on the surface of the total reflection prism used as the total reflection surface, and light is incident on the total reflection surface of the total reflection prism through the total reflection prism at an incident angle greater than the total reflection angle of the total reflection prism.

10. The method for achieving total reflection and polarization maintaining according to claim 9, characterized in that: The total reflection prism is a right-angled triangular prism, and the material used for the right-angled triangular prism is K9 glass with a refractive index of n=1.52, so that light passes through the total reflection prism at an incident angle of 45 degrees and is incident on the total reflection surface of the total reflection prism.

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