阅读说明：本技术 一种四方位消偏振分光棱镜及其制备方法 (Four-direction depolarization beam splitter prism and preparation method thereof ) 是由 黄文华 马新建 吴先云 廖洪平 王昌运 陈伟 陈秋华 于 2020-12-25 设计创作，主要内容包括：一种四方位消偏振分光棱镜,在五角棱镜的三个分光面上分别贴合有三个等腰直角棱镜,贴合面上镀制有由高折射率介质Ta2O5层和低折射率SiO2层依次交叠而成消偏振介质分光膜。本发明可实现四方位非偏振等光量分光,在多维度校准测量时减少误差、优化系统结果、降低成本；中心波长为632.8nm,提高了光学器件的适用范围；所述膜组工艺成熟、成本较低且损伤较高,可完全使用光控的膜层结构；利用光胶组合,较大程度提高损伤阈值；选用较高的角精度,可提高四方位光束分离后的准直度；组合后的分光棱镜外形规则,外形规则,便于光学器件的固定和使用,四方位出射光束规则,等光量,且光束准直度高,便于测量中使用。(Three isosceles right-angle prisms are respectively attached to three splitting surfaces of a pentagonal prism, and a depolarization medium splitting film formed by sequentially overlapping a high-refractive-index medium Ta2O5 layer and a low-refractive-index SiO2 layer is plated on the attaching surfaces. The invention can realize four-direction non-polarized equal-light-quantity light splitting, reduce errors, optimize system results and reduce cost during multi-dimensional calibration measurement; the central wavelength is 632.8nm, so that the application range of the optical device is improved; the film group has mature process, lower cost and higher damage, and can completely use a light-operated film layer structure; the damage threshold is greatly improved by using the optical cement combination; the high angular precision is selected, so that the collimation degree of the four-direction light beam after separation can be improved; the combined beam splitter prism has regular shape and regular shape, is convenient for fixing and using an optical device, has regular outgoing light beams in four directions and equal light quantity, has high light beam collimation degree and is convenient to use in measurement.)

1. A four-direction depolarizing beam splitter prism, comprising:

one surface of the pentagonal prism is an incident surface, the other adjacent surface of the pentagonal prism is an emergent surface, the other three surfaces of the pentagonal prism are a first light splitting surface, a second light splitting surface and a third light splitting surface, a first isosceles right prism, a second isosceles right prism and a third right isosceles right prism are respectively attached to the three splitting surfaces of the pentagonal prism, the three splitting surfaces are respectively attached to the bevel edges of the first isosceles right prism, the second isosceles right prism and the third right isosceles right prism, and a depolarization medium splitting film formed by sequentially overlapping a high-refractive-index medium Ta2O5 layer and a low-refractive-index SiO2 layer is plated between the splitting surfaces and the inclined surfaces;

a first depolarization medium light-splitting film is plated between the first light-splitting surface and the bevel edge of the first isosceles right-angle prism, and the spectrum indexes of the first depolarization medium light-splitting film are as follows: T/R25/75 ± 2%, | Tp-Ts | < 3%, wavelength 632.8nm, AOI 45 °;

a second depolarization medium light-splitting film is plated between the second light-splitting surface and the bevel edge of the second equal-waist right-angle prism, and the spectrum indexes of the second depolarization medium film are as follows: T/R33/67 ± 2%, | Tp-Ts | < 3%, wavelength 632.8nm, AOI 45 °;

a third depolarization medium light-splitting film is plated between the third light-splitting surface and the inclined surface of the third equal-waist right-angle prism, and the spectral indexes of the third depolarization medium film are as follows: T/R50/50 ± 2%, | Tp-Ts | < 3%, wavelength 632.8nm, AOI 45 °;

wherein T represents transmittance, R is reflectance, Tp and Ts are respectively polarization state P and polarization state S of transmitted light, and AOI is incident angle of light.

2. A four-way depolarizing splitting prism of claim 1,

the number of the first depolarizing medium beam splitting films is 34, and the number of the layers from near to far from the pentagonal prism 1 is as follows: 1.8156L, 0.7408H, 1.0577L, 0.8906H, 1.2276L, 0.9263H, 1.1397L, 0.811H, 0.9985L, 0.8068H, 1.2072L, 1.0311H, 1.3954L, 1.0695H, 1.3651L, 0.9952H, 1.1873L, 0.7984H, 0.9639L, 0.7428H, 1.0672L, 0.9189H, 1.3032L, 1.0483H, 1.391L, 1.067H, 1.2875L, 0.8982H, 0.961L, 0.7148H, 1.0363L, 0.8495H, 1.176L, 0.8644H, wherein the value H represents a Ta2O5 layer corresponding to an 1/4 wavelength optical thickness and the value L represents a SiO2 layer corresponding to a 1/4 wavelength optical thickness, the first depolarizing medium beam-splitting film having a center wavelength of 632.8 nm.

3. A four-way depolarizing splitting prism of claim 1,

the number of the second depolarizing medium beam splitting films is 36, and the layers are sequentially from near to far from the pentagonal prism 1: 2.4865L, 0.9894H, 1.2764L, 0.9375H, 1.1755L, 0.8398H, 1.0451L, 0.7694H, 1.0627L, 0.8801H, 1.3008L, 1.0612H, 1.4423L, 1.0834H, 1.4175L, 1.0316H, 1.2347L, 0.8333H, 0.9984L, 0.7345H, 1.0163L, 0.8536H, 1.2553L, 1.0283H, 1.4192L, 1.0855H, 1.4184L, 1.0109H, 1.1594L, 0.7616H, 0.9761L, 0.7699H, 1.0962L, 0.8956H, 1.2738L, 0.7494H, wherein the value H represents the Ta2O5 layer corresponding to an optical thickness of 1/4 wavelength, the value L represents the SiO2 layer corresponding to an optical thickness of 1/4 wavelength, and the second depolarizing medium spectroscopic film 4 has a center wavelength of 632.8 nm.

4. A four-way depolarizing splitting prism of claim 1,

the number of the third depolarizing medium beam-splitting film layers is 38, and the order of the layers from the near to the far from the pentagonal prism 1 is as follows: 3.662L, 0.7737H, 2.0077L, 1.1191H, 1.4092L, 0.9966H, 1.2388L, 0.8984H, 1.2009L, 0.9709H, 1.3621L, 1.1387H, 1.6406L, 1.2794H, 1.7191L, 1.2512H, 1.6128L, 1.0889H, 1.322L, 0.8919H, 1.1607L, 0.8648H, 1.2264L, 1.0666H, 1.5242L, 1.24H, 1.7015L, 1.283H, 1.6216L, 1.1281H, 1.305L, 0.9042H, 1.1459L, 0.8761H, 1.251L, 1.017H, 1.5227L, 1.1072H, wherein the value H represents a Ta2O5 layer corresponding to an optical thickness of 1/4 wavelength, the value L represents a SiO2 layer corresponding to an optical thickness of 1/4 wavelength, and the third depolarizing medium beam splitting film 6 has a center wavelength of 632.8 nm.

5. A four-way depolarizing splitting prism as recited in any of claims 1-4,

the longitudinal section of the pentagonal prism is axially symmetrical, the internal angles of the pentagonal prism are 90 degrees, 135 degrees, 90 degrees, 135 degrees and 90 degrees adjacent to two 135 degrees, the surfaces corresponding to 90 degrees are incidence surfaces and emission surfaces, the surfaces adjacent to 135 degrees and 90 degrees are first light splitting surfaces, the surfaces adjacent to 90 degrees and 90 degrees are second light splitting surfaces, the surfaces adjacent to 90 degrees and 135 degrees are third light splitting surfaces, the lengths of the three light splitting surfaces are the same, the sizes of the three isosceles right-angle prisms are the same, and the inclined surfaces of the isosceles right-angle prisms are the same as the sizes of the light splitting surfaces.

6. The four-direction depolarizing splitting prism of claim 5,

the cross section of the four-direction depolarization beam splitter prism is rectangular, and the shape of the four-direction depolarization beam splitter prism is a regular cube;

the four light beams split by the four-direction depolarization beam splitter prism are sequentially adjacent and spaced by 90 degrees.

7. The four-direction depolarizing splitting prism of claim 5,

the pentagonal prism and the light splitting surface of the isosceles right-angle prism are attached in an optical cement mode.

8. A four-way depolarizing splitting prism as recited in any of claims 5-7,

the pentagonal prism and the isosceles right-angle prism are made of the same material, and the material is free of impurities, bubbles and envelope and has emergent light deviation smaller than 30'; and/or the presence of a gas in the gas,

the material may be K9, D263T, B270, BK7 or FS; and/or the presence of a gas in the gas,

five surfaces of the pentagonal prism and three surfaces of the isosceles right-angle prism are polished; and/or the presence of a gas in the gas,

and antireflection films are plated on the light incident surface and the light emergent surface of the four-direction depolarization beam splitter prism.

9. A method of making a quadri-depolarising splitting prism according to any one of claims 1 to 8, comprising the steps of:

polishing step S110: polishing five surfaces of the pentagonal prism, two right-angle surfaces and inclined surfaces of the three isosceles right-angle prisms;

step S120 of plating a depolarization medium light-splitting film: selecting a high-refractive-index medium Ta2O5 layer and a low-refractive-index SiO2 layer as coating materials, and respectively coating the first depolarization medium spectroscopic film, the second depolarization medium spectroscopic film and the third depolarization medium spectroscopic film on the inclined planes of three isosceles right-angle prisms, wherein the outermost layer of the inclined plane of the isosceles right-angle prism is a low-dielectric SiO2 layer, and the innermost layer of the inclined plane of the isosceles right-angle prism is a high-dielectric Ta2O5 layer;

a light glue step S130: carrying out optical cement bonding on the coated isosceles right-angle prism and the three splitting surfaces of the pentagonal prism respectively;

an incident and exit surface coating step S140: and plating antireflection films with corresponding wave bands on the incident and emergent surfaces of the bonded prism.

10. The method of manufacturing a quadri-depolarising splitting prism according to claim 9, wherein:

in the step S120 of plating the depolarization medium splitting film, the depolarization medium splitting film is formed by respectively evaporating a high-refractive-index medium Ta2O5 layer and a low-refractive-index medium SiO2 layer on the inclined plane of the isosceles right-angle prism which is in contact with the pentagonal prism photoresist according to the following sequence,

the first depolarizing medium light-splitting film comprises the following layers in sequence from near to far from the pentagonal prism: 1.8156L, 0.7408H, 1.0577L, 0.8906H, 1.2276L, 0.9263H, 1.1397L, 0.811H, 0.9985L, 0.8068H, 1.2072L, 1.0311H, 1.3954L, 1.0695H, 1.3651L, 0.9952H, 1.1873L, 0.7984H, 0.9639L, 0.7428H, 1.0672L, 0.9189H, 1.3032L, 1.0483H, 1.391L, 1.067H, 1.2875L, 0.8982H, 0.961L, 0.7148H, 1.0363L, 0.8495H, 1.176L, 0.8644H;

the layers of the second depolarizing medium light-splitting film are sequentially from near to far from the pentagonal prism: 2.4865L, 0.9894H, 1.2764L, 0.9375H, 1.1755L, 0.8398H, 1.0451L, 0.7694H, 1.0627L, 0.8801H, 1.3008L, 1.0612H, 1.4423L, 1.0834H, 1.4175L, 1.0316H, 1.2347L, 0.8333H, 0.9984L, 0.7345H, 1.0163L, 0.8536H, 1.2553L, 1.0283H, 1.4192L, 1.0855H, 1.4184L, 1.0109H, 1.1594L, 0.7616H, 0.9761L, 0.7699H, 1.0962L, 0.8956H, 1.2738L, 0.7494H;

the layers of the third depolarizing medium light-splitting film are sequentially from near to far from the pentagonal prism: 3.662L, 0.7737H, 2.0077L, 1.1191H, 1.4092L, 0.9966H, 1.2388L, 0.8984H, 1.2009L, 0.9709H, 1.3621L, 1.1387H, 1.6406L, 1.2794H, 1.7191L, 1.2512H, 1.6128L, 1.0889H, 1.322L, 0.8919H, 1.1607L, 0.8648H, 1.2264L, 1.0666H, 1.5242L, 1.24H, 1.7015L, 1.283H, 1.6216L, 1.1281H, 1.305L, 0.9042H, 1.1459L, 0.8761H, 1.251L, 1.017H, 1.5227L, 1.1072H; wherein the value H represents a Ta2O5 layer corresponding to an optical thickness of 1/4 wavelengths, and the value L represents a SiO2 layer corresponding to an optical thickness of 1/4 wavelengths, with a center wavelength of 632.8 nm.

Technical Field

The invention relates to the field of lenses, in particular to a four-direction depolarization beam splitter prism and a preparation method thereof.

Background

The advantages of the laser measurement technology such as rapidness, non-contact, miniaturization, high precision and capability of simultaneously measuring a plurality of degrees of freedom become one of the essential tools for the development of the fields such as modern precision machining, micro-mechanical assembly, nanotechnology and the like. In such various optical path systems, multi-directional light splitting is performed with high precision due to the light splitting prism; becomes one of the important optical components in the system. However, when light is obliquely incident, the film shows different effective refractive indexes for P component and S component of polarized light, and the film layer inevitably generates a polarization effect. And thus needs to be effectively controlled or the use is greatly limited.

At present, when an interference method is commonly adopted for measurement, a single two-direction beam splitting is mostly adopted by a beam splitter prism for one-dimensional length displacement or two-dimensional angle displacement measurement; the requirement of simultaneously carrying out dynamic measurement of a plurality of parameters cannot be met. Thus, when the multi-direction measurement is carried out, the introduced error is large, the result is complex, the adjustment is inconvenient, and the cost is high.

In addition, some existing light splitting prisms are irregular in appearance, and are inconvenient for fixing and using optical devices.

Therefore, how to prepare a prism for splitting light beams in multiple directions, for example, four directions, to eliminate polarization in the splitting process, which is suitable for commonly used light wavelengths, and has a regular shape, which is convenient for fixing and using an optical device, becomes a technical problem to be solved in the prior art.

Disclosure of Invention

The invention aims to provide a four-direction depolarization beam splitter prism and a preparation method thereof, which can realize four-direction unpolarized equal-light-quantity beam splitting so as to meet the four-direction beam splitting, reduce errors, optimize system results and reduce cost during multi-dimensional calibration measurement, and have regular appearance, and are convenient for fixing and using optical devices.

In order to achieve the purpose, the invention adopts the following technical scheme:

a four-direction depolarizing beam splitter prism, comprising:

one surface of the pentagonal prism is an incident surface, the other adjacent surface of the pentagonal prism is an emergent surface, the other three surfaces of the pentagonal prism are a first light splitting surface, a second light splitting surface and a third light splitting surface, a first isosceles right prism, a second isosceles right prism and a third right isosceles right prism are respectively attached to the three splitting surfaces of the pentagonal prism, the three splitting surfaces are respectively attached to the bevel edges of the first isosceles right prism, the second isosceles right prism and the third right isosceles right prism, and a depolarization medium splitting film formed by sequentially overlapping a high-refractive-index medium Ta2O5 layer and a low-refractive-index SiO2 layer is plated between the splitting surfaces and the inclined surfaces;

a first depolarization medium light-splitting film is plated between the first light-splitting surface and the bevel edge of the first isosceles right-angle prism, and the spectrum indexes of the first depolarization medium light-splitting film are as follows: T/R25/75 ± 2%, | Tp-Ts | < 3%, wavelength 632.8nm, AOI 45 °;

a second depolarization medium light-splitting film is plated between the second light-splitting surface and the bevel edge of the second equal-waist right-angle prism, and the spectrum indexes of the second depolarization medium film are as follows: T/R33/67 ± 2%, | Tp-Ts | < 3%, wavelength 632.8nm, AOI 45 °;

a third depolarization medium light-splitting film is plated between the third light-splitting surface and the inclined surface of the third equal-waist right-angle prism, and the spectral indexes of the third depolarization medium film are as follows: T/R50/50 ± 2%, | Tp-Ts | < 3%, wavelength 632.8nm, AOI 45 °;

wherein T represents transmittance, R is reflectance, Tp and Ts are respectively polarization state P and polarization state S of transmitted light, and AOI is incident angle of light.

Optionally, the number of the first depolarizing medium beam-splitting films is 34, and the order of the layers from near to far from the pentagonal prism 1 is as follows: 1.8156L, 0.7408H, 1.0577L, 0.8906H, 1.2276L, 0.9263H, 1.1397L, 0.811H, 0.9985L, 0.8068H, 1.2072L, 1.0311H, 1.3954L, 1.0695H, 1.3651L, 0.9952H, 1.1873L, 0.7984H, 0.9639L, 0.7428H, 1.0672L, 0.9189H, 1.3032L, 1.0483H, 1.391L, 1.067H, 1.2875L, 0.8982H, 0.961L, 0.7148H, 1.0363L, 0.8495H, 1.176L, 0.8644H, wherein the value H represents a Ta2O5 layer corresponding to an 1/4 wavelength optical thickness and the value L represents a SiO2 layer corresponding to a 1/4 wavelength optical thickness, the first depolarizing medium beam-splitting film having a center wavelength of 632.8 nm.

Optionally, the number of the second depolarizing medium beam-splitting films is 36, and the respective layers sequentially from near to far from the pentagonal prism 1: 2.4865L, 0.9894H, 1.2764L, 0.9375H, 1.1755L, 0.8398H, 1.0451L, 0.7694H, 1.0627L, 0.8801H, 1.3008L, 1.0612H, 1.4423L, 1.0834H, 1.4175L, 1.0316H, 1.2347L, 0.8333H, 0.9984L, 0.7345H, 1.0163L, 0.8536H, 1.2553L, 1.0283H, 1.4192L, 1.0855H, 1.4184L, 1.0109H, 1.1594L, 0.7616H, 0.9761L, 0.7699H, 1.0962L, 0.8956H, 1.2738L, 0.7494H, wherein the value H represents the Ta2O5 layer corresponding to an optical thickness of 1/4 wavelength, the value L represents the SiO2 layer corresponding to an optical thickness of 1/4 wavelength, and the second depolarizing medium spectroscopic film 4 has a center wavelength of 632.8 nm.

Optionally, the number of the third depolarizing medium beam-splitting films is 38, and the order of the layers from the proximal to the distal from the pentagonal prism 1 is as follows: 3.662L, 0.7737H, 2.0077L, 1.1191H, 1.4092L, 0.9966H, 1.2388L, 0.8984H, 1.2009L, 0.9709H, 1.3621L, 1.1387H, 1.6406L, 1.2794H, 1.7191L, 1.2512H, 1.6128L, 1.0889H, 1.322L, 0.8919H, 1.1607L, 0.8648H, 1.2264L, 1.0666H, 1.5242L, 1.24H, 1.7015L, 1.283H, 1.6216L, 1.1281H, 1.305L, 0.9042H, 1.1459L, 0.8761H, 1.251L, 1.017H, 1.5227L, 1.1072H, wherein the value H represents a Ta2O5 layer corresponding to an optical thickness of 1/4 wavelength, the value L represents a SiO2 layer corresponding to an optical thickness of 1/4 wavelength, and the third depolarizing medium beam splitting film 6 has a center wavelength of 632.8 nm.

Optionally, the longitudinal section of the pentagonal prism is axisymmetric, the internal angles of the pentagonal prism are 90 °,135 °, 90 °, and 90 ° adjacent to two 135 ° angles, the surfaces corresponding to 90 ° adjacent to the two 135 ° angles are the incident surface and the exit surface, wherein the surfaces adjacent to the 135 ° and 90 ° angles are the first light splitting surfaces, the surfaces adjacent to the 90 ° and 90 ° angles are the second light splitting surfaces, the surfaces adjacent to the 90 ° and 135 ° angles are the third light splitting surfaces, the three light splitting surfaces have the same length, the three isosceles right-angle prisms have the same size, and the inclined surfaces of the isosceles right-angle prisms have the same size as the light splitting surfaces.

Optionally, the cross section of the four-direction depolarizing beam splitter prism is rectangular, and the shape of the four-direction depolarizing beam splitter prism is a regular cube;

the four light beams split by the four-direction depolarization beam splitter prism are sequentially adjacent and spaced by 90 degrees.

Optionally, the pentagonal prism is attached to the splitting surface of the isosceles right-angle prism in an optical cement manner.

Optionally, the pentagonal prism and the isosceles right-angle prism are made of the same material, and the material is free of impurities, bubbles and envelope, and the deviation of emergent light is less than 30 ″; and/or the presence of a gas in the gas,

the material may be K9, D263T, B270, BK7 or FS; and/or the presence of a gas in the gas,

five surfaces of the pentagonal prism and three surfaces of the isosceles right-angle prism are polished; and/or the presence of a gas in the gas,

and antireflection films are plated on the light incident surface and the light emergent surface of the four-direction depolarization beam splitter prism.

The invention further discloses a preparation method of the quartering position depolarization beam splitter prism, which comprises the following steps:

polishing step S110: polishing five surfaces of the pentagonal prism, two right-angle surfaces and inclined surfaces of the three isosceles right-angle prisms;

step S120 of plating a depolarization medium light-splitting film: selecting a high-refractive-index medium Ta2O5 layer and a low-refractive-index SiO2 layer as coating materials, and respectively coating the first depolarization medium spectroscopic film, the second depolarization medium spectroscopic film and the third depolarization medium spectroscopic film on the inclined planes of three isosceles right-angle prisms, wherein the outermost layer of the inclined plane of the isosceles right-angle prism is a low-dielectric SiO2 layer, and the innermost layer of the inclined plane of the isosceles right-angle prism is a high-dielectric Ta2O5 layer;

a light glue step S130: carrying out optical cement bonding on the coated isosceles right-angle prism and the three splitting surfaces of the pentagonal prism respectively;

an incident and exit surface coating step S140: and plating antireflection films with corresponding wave bands on the incident and emergent surfaces of the bonded prism.

Optionally, in the step S120 of plating the depolarizing medium splitting film, a depolarizing medium splitting film composed of a high refractive index medium Ta2O5 layer and a low refractive index medium SiO2 layer is respectively evaporated on the isosceles right-angle prism inclined plane of the pentagonal prism optical cement in the following order,

the first depolarizing medium light-splitting film comprises the following layers in sequence from near to far from the pentagonal prism: 1.8156L, 0.7408H, 1.0577L, 0.8906H, 1.2276L, 0.9263H, 1.1397L, 0.811H, 0.9985L, 0.8068H, 1.2072L, 1.0311H, 1.3954L, 1.0695H, 1.3651L, 0.9952H, 1.1873L, 0.7984H, 0.9639L, 0.7428H, 1.0672L, 0.9189H, 1.3032L, 1.0483H, 1.391L, 1.067H, 1.2875L, 0.8982H, 0.961L, 0.7148H, 1.0363L, 0.8495H, 1.176L, 0.8644H;

the layers of the second depolarizing medium light-splitting film are sequentially from near to far from the pentagonal prism: 2.4865L, 0.9894H, 1.2764L, 0.9375H, 1.1755L, 0.8398H, 1.0451L, 0.7694H, 1.0627L, 0.8801H, 1.3008L, 1.0612H, 1.4423L, 1.0834H, 1.4175L, 1.0316H, 1.2347L, 0.8333H, 0.9984L, 0.7345H, 1.0163L, 0.8536H, 1.2553L, 1.0283H, 1.4192L, 1.0855H, 1.4184L, 1.0109H, 1.1594L, 0.7616H, 0.9761L, 0.7699H, 1.0962L, 0.8956H, 1.2738L, 0.7494H;

the layers of the third depolarizing medium light-splitting film are sequentially from near to far from the pentagonal prism: 3.662L, 0.7737H, 2.0077L, 1.1191H, 1.4092L, 0.9966H, 1.2388L, 0.8984H, 1.2009L, 0.9709H, 1.3621L, 1.1387H, 1.6406L, 1.2794H, 1.7191L, 1.2512H, 1.6128L, 1.0889H, 1.322L, 0.8919H, 1.1607L, 0.8648H, 1.2264L, 1.0666H, 1.5242L, 1.24H, 1.7015L, 1.283H, 1.6216L, 1.1281H, 1.305L, 0.9042H, 1.1459L, 0.8761H, 1.251L, 1.017H, 1.5227L, 1.1072H; wherein the value H represents a Ta2O5 layer corresponding to an optical thickness of 1/4 wavelengths, and the value L represents a SiO2 layer corresponding to an optical thickness of 1/4 wavelengths, with a center wavelength of 632.8 nm.

In summary, the invention has the following advantages:

1. the four-direction depolarization beam splitter prism and the preparation method thereof are obtained, so that four-direction unpolarized equal-light-quantity beam splitting is realized, four-direction light splitting is met, errors are reduced during multi-dimensional calibration measurement, a system result is optimized, and cost is reduced;

2. the central wavelength is 632.8nm, which is the common calibration wavelength of the optical mechanism, and the application range of the optical device is improved;

3. ta2O5 and SiO2 are selected to be combined as a coating material, so that the coating material has the advantages of mature process, lower cost, higher damage and the like; the film structure completely using light control can be designed, and compared with a crystal control process, the film structure can reduce accumulated errors and reduce preparation difficulty; finally realizing the four-direction equal-light-quantity light splitting of any polarization state;

4. selecting a proper flatness prism, performing optical cement combination, and improving the damage threshold value to a greater extent compared with a cemented prism; the high angular precision is selected, so that the collimation degree of the four-direction light beam after separation can be improved;

5. the combined beam splitter prism has regular shape and regular shape, so that the optical device is convenient to fix and use, the four-direction emergent light beam is regular, the light quantity is equal, the light beam collimation degree is high, and the light beam is convenient to use in measurement.

Drawings

FIG. 1 is a schematic diagram of a structure of a four-direction depolarizing beam-splitting prism according to an embodiment of the present invention;

FIG. 2 is a graph of transmission of a first depolarizing medium splitting film of a four-orientation depolarizing beam splitter prism in accordance with an embodiment of the present invention;

FIG. 3 is a graph of the reflection of a first depolarizing medium splitting film of a four-orientation depolarizing beam splitter prism in accordance with an embodiment of the present invention;

FIG. 4 is a transmission curve of a second depolarizing medium splitting film of a four-orientation depolarizing beam splitter prism in accordance with an exemplary embodiment of the present invention;

FIG. 5 is a graph of the reflection of a second depolarizing-medium splitting film of a four-orientation depolarizing beam-splitting prism, according to an embodiment of the present invention;

FIG. 6 is a transmission curve of a third depolarizing medium splitting film of a four-orientation depolarizing beam splitter prism in accordance with an exemplary embodiment of the present invention;

FIG. 7 is a graph of the reflection of a third depolarizing medium splitting film of a four-orientation depolarizing beam splitter prism, according to an embodiment of the present invention.

The reference numerals in the drawings respectively refer to the technical features:

1. a pentagonal prism; 2. a first depolarizing medium light-splitting film; 3. a first isosceles right angle prism; 4. a second depolarizing medium light-splitting film; 5. a second isosceles right-angle prism; 6. a third depolarizing medium light-splitting film; 7. and a third iso-waist right-angle prism.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

The invention is characterized in that the sizes of the pentagonal prism and the three isosceles right-angle prisms are designed to ensure that the shape of the attached beam splitting prism is regular, the regular light emitting in four directions is realized, the collimation degree of a light beam is high, and three different depolarization dielectric films are plated on the edges of the pentagonal prism, which are attached to the isosceles right-angle prisms, so that the depolarization effects of different transmittances are realized, and the equal-light-quantity light emitting in four directions is finally realized.

Referring to fig. 1, a schematic structural diagram of a four-direction depolarizing beam splitter prism according to an embodiment of the present invention is shown, the beam splitter prism comprising:

one surface of the pentagonal prism 1 is an incident surface, the other adjacent surface is an emergent surface, the other three surfaces are a first light splitting surface, a second light splitting surface and a third light splitting surface, a first isosceles right prism 3, a second isosceles right prism 5 and a third right isosceles prism 7 are respectively attached to the three splitting surfaces of the pentagonal prism 1, the three splitting surfaces are respectively attached to the bevel edges of the first isosceles right prism 3, the second isosceles right prism 5 and the third right isosceles prism 7, a depolarizing medium splitting film is formed by sequentially overlapping a high-refractive-index medium Ta2O5 layer and a low-refractive-index SiO2 layer between the splitting surfaces and the bevel surfaces in a plating manner,

a first depolarization medium light-splitting film 2 is plated between the first light splitting surface and the bevel edge of the first isosceles right-angle prism 3, and the spectrum indexes of the first depolarization medium light-splitting film 2 are as follows: T/R25/75 ± 2%, | Tp-Ts | < 3%, wavelength 632.8nm, AOI 45 °; a second depolarization medium light-splitting film 4 is plated between the second light-splitting surface and the bevel edge of the second equal-waist right-angle prism 5, and the spectrum indexes of the second depolarization medium film 4 are as follows: T/R33/67 ± 2%, | Tp-Ts | < 3%, wavelength 632.8nm, AOI 45 °; a third depolarizing medium light-splitting film 6 is plated between the third light-splitting surface and the inclined surface of the third isosceles right-angle prism 7, and the spectral indexes of the third depolarizing medium film 6 are as follows: T/R50/50 ± 2%, | Tp-Ts | < 3%, wavelength 632.8nm, AOI 45 °; wherein T represents transmittance, R is reflectance, Tp and Ts are respectively polarization state P and polarization state S of transmitted light, and AOI is incident angle of light.

Therefore, the three splitting surfaces of the pentagonal prism 1 are respectively attached to the isosceles right-angle prism, and the attaching surface is plated with the depolarization medium splitting film, so that equal-light-quantity splitting is performed by using the splitting surfaces and the depolarization medium splitting film, equal-quantity splitting is performed in four directions, and the light splitting quantity of the incident light 1/4 is obtained in the four directions.

Referring to fig. 2 and 3, there are shown reflection and transmission graphs of the first depolarizing-medium spectroscopic film 2, the first depolarizing-medium spectroscopic film 2 has 34 layers, and the layers are, in order from the proximal to the distal from the penta prism 1: 1.8156L, 0.7408H, 1.0577L, 0.8906H, 1.2276L, 0.9263H, 1.1397L, 0.811H, 0.9985L, 0.8068H, 1.2072L, 1.0311H, 1.3954L, 1.0695H, 1.3651L, 0.9952H, 1.1873L, 0.7984H, 0.9639L, 0.7428H, 1.0672L, 0.9189H, 1.3032L, 1.0483H, 1.391L, 1.067H, 1.2875L, 0.8982H, 0.961L, 0.7148H, 1.0363L, 0.8495H, 1.176L, 0.8644H, wherein the value H represents a Ta2O5 layer corresponding to an 1/4 wavelength optical thickness and the value L represents a SiO2 layer corresponding to a 1/4 wavelength optical thickness, the first depolarizing medium beam-splitting film having a center wavelength of 632.8 nm.

Referring to fig. 4 and 5, reflection and transmission graphs of the second depolarizing-medium spectroscopic film 4 are shown, the number of the second depolarizing-medium spectroscopic film 4 is 36, and the layers are sequentially in order from the proximal to the distal from the penta prism 1: 2.4865L, 0.9894H, 1.2764L, 0.9375H, 1.1755L, 0.8398H, 1.0451L, 0.7694H, 1.0627L, 0.8801H, 1.3008L, 1.0612H, 1.4423L, 1.0834H, 1.4175L, 1.0316H, 1.2347L, 0.8333H, 0.9984L, 0.7345H, 1.0163L, 0.8536H, 1.2553L, 1.0283H, 1.4192L, 1.0855H, 1.4184L, 1.0109H, 1.1594L, 0.7616H, 0.9761L, 0.7699H, 1.0962L, 0.8956H, 1.2738L, 0.7494H, wherein the value H represents the Ta2O5 layer corresponding to an optical thickness of 1/4 wavelength, the value L represents the SiO2 layer corresponding to an optical thickness of 1/4 wavelength, and the second depolarizing medium spectroscopic film 4 has a center wavelength of 632.8 nm.

Referring to fig. 6 and 7, reflection and transmission graphs of the third depolarizing medium light-splitting film 6 are shown, the number of the third depolarizing medium light-splitting film 6 is 38, and the layers are sequentially in order from the penta prism 1 from near to far: 3.662L, 0.7737H, 2.0077L, 1.1191H, 1.4092L, 0.9966H, 1.2388L, 0.8984H, 1.2009L, 0.9709H, 1.3621L, 1.1387H, 1.6406L, 1.2794H, 1.7191L, 1.2512H, 1.6128L, 1.0889H, 1.322L, 0.8919H, 1.1607L, 0.8648H, 1.2264L, 1.0666H, 1.5242L, 1.24H, 1.7015L, 1.283H, 1.6216L, 1.1281H, 1.305L, 0.9042H, 1.1459L, 0.8761H, 1.251L, 1.017H, 1.5227L, 1.1072H, wherein the value H represents a Ta2O5 layer corresponding to an optical thickness of 1/4 wavelength, the value L represents a SiO2 layer corresponding to an optical thickness of 1/4 wavelength, and the third depolarizing medium beam splitting film 6 has a center wavelength of 632.8 nm.

Therefore, the Ta2O5 and SiO2 are selected to be combined as coating materials, wherein the outermost layer of the inclined plane of the isosceles right-angle prism is a SiO2 layer with low dielectric constant, and the innermost layer of the inclined plane of the isosceles right-angle prism is a Ta2O5 layer with high dielectric constant, so that the coating has the advantages of mature process, low cost, high damage and the like.

Furthermore, the pentagonal prism 1 of the present invention has axially symmetric longitudinal sections, the internal angles of which are 90 °,135 °, 90 °, 90 ° and 90 ° adjacent to two 135 ° angles, the 90 ° corresponding surfaces being incident surfaces and emergent surfaces, wherein the surfaces adjacent to the 135 ° and 90 ° angles and close to the emergent surfaces are first light splitting surfaces, the surfaces adjacent to the 90 ° and 90 ° angles are second light splitting surfaces, the surfaces adjacent to the 90 ° and 135 ° angles and close to the incident surfaces are third light splitting surfaces, the lengths of the three light splitting surfaces are the same, the sizes of the three isosceles right-angle prisms are the same, and the inclined surfaces of the isosceles right-angle prisms and the light splitting surfaces are the same.

Therefore, the section of the attached four-direction depolarization beam splitter prism is rectangular, the shape of the attached four-direction depolarization beam splitter prism is regular cube, and the shape of the attached four-direction depolarization beam splitter prism is regular, so that the optical device is convenient to fix and use.

And the four light beams split by the four-direction depolarization beam splitter prism are sequentially adjacent and spaced by 90 degrees, so that the four-beam depolarization beam splitter prism can be used for multi-dimensional calibration and measurement, and has fewer errors and lower cost.

Furthermore, the pentagonal prism 1 is attached to the splitting surface of the isosceles right-angle prism in an optical cement mode, so that the damage threshold of the optical device can be remarkably improved compared with the gluing mode.

The pentagonal prism and the isosceles right-angle prism are made of the same material, and the material is free of impurities, bubbles and envelope and has the deviation of emergent light less than 30 ″.

The material may be K9, D263T, B270, BK7 or FS.

Five surfaces of the pentagonal prism and three surfaces of the isosceles right-angle prism are polished.

The light incident surface and the light emergent surface of the four-direction depolarization beam splitter prism are plated with antireflection films,

furthermore, the invention further discloses a preparation method of the quadri-position depolarization beam splitter prism, which comprises the following steps:

polishing step S110: polishing five surfaces of the pentagonal prism 1 and two right-angle surfaces and inclined surfaces of the three isosceles right-angle prisms;

step S120 of plating a depolarization medium light-splitting film: selecting a high-refractive-index medium Ta2O5 layer and a low-refractive-index SiO2 layer as coating materials, and respectively coating the first depolarization medium spectroscopic film, the second depolarization medium spectroscopic film and the third depolarization medium spectroscopic film on the inclined planes of three isosceles right-angle prisms, wherein the outermost layer of the inclined plane of the isosceles right-angle prism is a low-dielectric SiO2 layer, and the innermost layer of the inclined plane of the isosceles right-angle prism is a high-dielectric Ta2O5 layer;

a light glue step S130: the coated isosceles right-angle prism is respectively in optical adhesive fit with the three splitting surfaces of the pentagonal prism, and the damage threshold of components can be obviously improved by contrast gluing;

an incident and exit surface coating step S140: and plating antireflection films with corresponding wave bands on the incident and emergent surfaces of the bonded prism.

Further, in the step S120 of plating the depolarizing medium beam splitting film, a layer of high refractive index medium Ta2O5 and a layer of low refractive index medium SiO2 are respectively evaporated on the inclined plane of the isosceles right-angle prism with the pentagonal prism glue according to the following sequence to form the depolarizing medium beam splitting film, wherein the layers of the first depolarizing medium beam splitting film are sequentially from near to far from the pentagonal prism 1: 1.8156L, 0.7408H, 1.0577L, 0.8906H, 1.2276L, 0.9263H, 1.1397L, 0.811H, 0.9985L, 0.8068H, 1.2072L, 1.0311H, 1.3954L, 1.0695H, 1.3651L, 0.9952H, 1.1873L, 0.7984H, 0.9639L, 0.7428H, 1.0672L, 0.9189H, 1.3032L, 1.0483H, 1.391L, 1.067H, 1.2875L, 0.8982H, 0.961L, 0.7148H, 1.0363L, 0.8495H, 1.176L, 0.8644H; the layers of the second depolarizing medium light-splitting film are sequentially from near to far from the pentagonal prism 1: 2.4865L, 0.9894H, 1.2764L, 0.9375H, 1.1755L, 0.8398H, 1.0451L, 0.7694H, 1.0627L, 0.8801H, 1.3008L, 1.0612H, 1.4423L, 1.0834H, 1.4175L, 1.0316H, 1.2347L, 0.8333H, 0.9984L, 0.7345H, 1.0163L, 0.8536H, 1.2553L, 1.0283H, 1.4192L, 1.0855H, 1.4184L, 1.0109H, 1.1594L, 0.7616H, 0.9761L, 0.7699H, 1.0962L, 0.8956H, 1.2738L, 0.7494H; the layers of the third depolarizing medium light-splitting film are sequentially from near to far from the pentagonal prism 1: 3.662L, 0.7737H, 2.0077L, 1.1191H, 1.4092L, 0.9966H, 1.2388L, 0.8984H, 1.2009L, 0.9709H, 1.3621L, 1.1387H, 1.6406L, 1.2794H, 1.7191L, 1.2512H, 1.6128L, 1.0889H, 1.322L, 0.8919H, 1.1607L, 0.8648H, 1.2264L, 1.0666H, 1.5242L, 1.24H, 1.7015L, 1.283H, 1.6216L, 1.1281H, 1.305L, 0.9042H, 1.1459L, 0.8761H, 1.251L, 1.017H, 1.5227L, 1.1072H; wherein the value H represents a Ta2O5 layer corresponding to an optical thickness of 1/4 wavelengths, and the value L represents a SiO2 layer corresponding to an optical thickness of 1/4 wavelengths, with a center wavelength of 632.8 nm.

In summary, the invention has the following advantages:

1. the four-direction depolarization beam splitter prism and the preparation method thereof are obtained, so that four-direction unpolarized equal-light-quantity beam splitting is realized, four-direction light splitting is met, errors are reduced during multi-dimensional calibration measurement, a system result is optimized, and cost is reduced;

2. the central wavelength is 632.8nm, which is the common calibration wavelength of the optical mechanism, and the application range of the optical device is improved;

3. ta2O5 and SiO2 are selected to be combined as a coating material, so that the coating material has the advantages of mature process, lower cost, higher damage and the like; the film structure completely using light control can be designed, and compared with a crystal control process, the film structure can reduce accumulated errors and reduce preparation difficulty; finally realizing the four-direction equal-light-quantity light splitting of any polarization state;

4. selecting a proper flatness prism, performing optical cement combination, and improving the damage threshold value to a greater extent compared with a cemented prism; the high angular precision is selected, so that the collimation degree of the four-direction light beam after separation can be improved;

5. the combined beam splitter prism has regular shape and regular shape, so that the optical device is convenient to fix and use, the four-direction emergent light beam is regular, the light quantity is equal, the light beam collimation degree is high, and the light beam is convenient to use in measurement.

While the invention has been described in further detail with reference to specific preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.