Multispectral ultra-wide spectrum color separation prism and processing method thereof

Abstract

The invention relates to the technical field of optical devices, and discloses a multispectral ultra-wide spectrum color separation prism and a processing method thereof.The ultra-wide spectrum color separation prism comprises a prism A, a prism B and a prism C. The color separation face of the prism A is connected to the incident face of the prism B, and the color separation face of the prism B is connected to the incident face of the prism C; the color separation surface of the prism A is plated with a color separation film S1, so that visible light is reflected, and infrared light is transmitted; the color separation surface of the prism B is plated with a color separation film S2, so that short-wave infrared light is reflected, and medium-wave and long-wave infrared light is transmitted; the color separation surface of the prism C is plated with a color separation film S3, so that medium-wave infrared light is reflected, and long-wave infrared light is transmitted; finally, the incident light is finely divided into visible light, short-wave infrared light, medium-wave infrared light and long-wave infrared light. The three prisms are adopted to realize color separation of four spectrums, so that color separation of visible light and infrared light is met, fine color separation of the infrared light is met, and the device and the method can be applied to wider application scenes.

Description

Technical Field

[0001] The invention relates to the technical field of optical devices, and in particular to a multi-spectrum ultra-wide spectrum color separation prism and a processing method thereof. Background Art

[0002] A dichroic prism (also called a dispersion prism or a spectrum prism) is a common optical element, usually made of transparent materials (such as glass or quartz), used to decompose white light into a spectrum of its component colors. This process is based on the different refractive indices of light of different wavelengths when passing through a prism, so that light of different colors is refracted at different angles when leaving the prism. Currently, commonly used dichroic prisms are generally applied to the visible light band, for example, to separate white light into red, green and blue. The structure usually has three prisms A, B and C arranged adjacent to each other in sequence, with an air gap structure between the A and B prisms, and glue glued between the B and C prisms. A, B and C prisms are generally made of optical glass materials, and the application wavelength is generally also in the visible light part. Special applications can be extended to near-infrared wavelengths, but they cannot be applied to the ultra-wide spectrum of visible + infrared, and materials, glue and coatings in the processing process are all technical difficulties that affect processing efficiency and quality.

[0003] At present, the spatial multi-spectral remote sensing system needs to separate light of different wavelengths and then match different detectors for imaging applications. This application requires a color separation device to separate the light signals of different wavelengths. The commonly used imaging spectrum is an ultra-wide spectrum, including visible light (wavelength 0.4-0.7um) and infrared light. Infrared light can be divided into short-wave infrared light (wavelength 0.85-1.65um), medium-wave infrared light (wavelength 3-5um), and long-wave infrared light (wavelength 8-12um). However, the existing color separation prism cannot meet the color separation requirements of multiple spectra. Therefore, how to provide an ultra-wide spectrum color separation prism that can realize multi-spectral color separation of visible light and infrared light has become a technical problem that needs to be solved urgently in this field.

[0004] Invention patent content

[0005] The purpose of the present invention is to provide a multi-spectrum ultra-wide spectrum color separation prism and a processing method thereof, which can realize ultra-wide spectrum color separation of visible light and infrared light, and further realize refined color separation of short wave, medium wave and long wave of infrared light, with wider applicability, and optimize the combined structure of three prisms to improve the prism color separation performance.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A multi-spectral ultra-wide spectrum color separation prism, comprising a prism A, a prism B, and a prism C, wherein the prism A, the prism B, and the prism C are all triangular prisms, and the prism A, the prism B, and the prism C all have an incident surface, an exit surface, and a color separation surface for light, the color separation surface of the prism A is adjacent to the incident surface of the prism B, and the color separation surface of the prism B is adjacent to the incident surface of the prism C;

[0008] The dichroic surface of the prism A is coated with a dichroic film S1, which reflects visible light and transmits infrared light. The visible light is totally reflected at the incident surface of the prism A to form an output light 1, which is emitted from the output surface of the prism A.

[0009] The dichroic surface of the prism B is coated with a dichroic film S2, so that short-wave infrared light is reflected and medium-wave and long-wave infrared light are transmitted. The short-wave infrared light is totally reflected at the incident surface of the prism B to form an output light 2, which is emitted from the output surface of the prism B.

[0010] The dichroic surface of the prism C is coated with a dichroic film S3, so that the medium-wave infrared light is reflected to form the output light three, and the long-wave infrared light is transmitted to form the output light four. The output light three is emitted from the dichroic surface of the prism C, and the output light four is emitted from the output surface of the prism C.

[0011] Furthermore, the prism A and the prism B, and the prism B and the prism C are combined together by air gap bonding.

[0012] Furthermore, the material of the prism A, the prism B, and the prism C is ZNS, ZNSE, or BAF2.

[0013] Furthermore, the angles between the incident surface of the prism A and the color separation surface and the exit surface are θ1 and θ2 respectively, the angles between the incident surface of the prism B and the color separation surface and the exit surface are θ4 and θ3 respectively, and the angles between the color separation surface of the prism C and the incident surface and the exit surface are θ5 and θ6 respectively, wherein the degrees of each angle are θ1=θ6, θ2=θ3=θ4=θ5.

[0014] Furthermore, the total reflection angle of the prism A is θ 反 , 2*θ1 and θ2 are greater than θ 反 .

[0015] Furthermore, the color separation characteristics of the color separation film S1 are: R>95%@0.4-0.7um, T>99%@0.85-1.65um&@3-5um&@8-12um;

[0016] The color separation characteristics of the color separation film S2 are: R>95%@0.85-1.65um, T>99%@3-5um&@8-12um;

[0017] The color separation characteristics of the color separation film S3 are: R>95%@3-5um, T>99%@8-12um;

[0018] Wherein, R represents reflectivity and T represents transmittance.

[0019] Furthermore, the incident surfaces and the exit surfaces of the prism A, the prism B and the prism C are plated with anti-reflection films.

[0020] The present invention also provides a method for processing a multi-spectrum ultra-wide spectrum color separation prism, which is applied to prepare the multi-spectrum ultra-wide spectrum color separation prism, and comprises the following steps:

[0021] Three prisms are processed by optical cold processing, namely prism A, prism B, and prism C, and the surfaces of the three prisms are polished. The finish of the optical surface of each prism is better than S / D=60 / 40;

[0022] The dichroic surface of prism A is coated with a dichroic film S1 to reflect visible light and transmit infrared light;

[0023] A dichroic film S2 is coated on the dichroic surface of prism B to reflect short-wave infrared light and transmit medium-wave and long-wave infrared light;

[0024] A dichroic film S3 is coated on the dichroic surface of the prism C to reflect the mid-wave infrared light and transmit the long-wave infrared light;

[0025] The incident surface and the exit surface of prism A, prism B and prism C are respectively coated with anti-reflection films;

[0026] The color separation surface of prism A and the incident surface of prism B, and the color separation surface of prism B and the incident surface of prism C are combined together by air gaps.

[0027] Furthermore, the air gap is a 10 um air gap formed at the bonding interface of adjacent prisms using micro beads or micro gaskets.

[0028] According to the specific embodiments provided by the present invention, the multi-spectrum ultra-wide spectrum color separation prism and the processing method thereof provided by the present invention disclose the following technical effects: different color separation films are respectively arranged between the three prisms used to achieve color separation of spectra in different bands, and the incident light is separated into visible light and infrared light after passing through prism A, and the visible light is totally reflected out; the transmitted infrared light is separated into short-wave infrared light and medium-wave + long-wave infrared light after passing through prism B, and the short-wave infrared light is totally reflected out; the transmitted medium-wave + long-wave infrared light is separated into medium-wave infrared light and medium-wave infrared light after passing through prism C. Infrared light and long-wave infrared light, medium-wave infrared light is emitted after reflection, and long-wave infrared light is emitted after transmission. Finally, the incident light is finely divided into visible light, short-wave infrared light, medium-wave infrared light and long-wave infrared light, realizing multi-spectral color separation, which not only meets the color separation of visible light and infrared light, but also meets the fine color separation of infrared light, and can be applied to a wider range of application scenarios; in addition, the present invention further limits the combination of adjacent prisms by combining them through air gaps, which can effectively avoid the problem of large infrared absorption by glue and improve the color separation performance of prisms. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 It is a schematic structural diagram of the multi-spectrum ultra-wide spectrum color separation prism of the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the invention patent, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "center", "longitudinal", "lateral", "vertical", "horizontal" and the like indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the 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 a limitation on the invention. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a centered element at the same time.

[0033] The purpose of the present invention is to provide a multi-spectrum ultra-wide spectrum color separation prism and a processing method thereof, so as to realize visible + infrared ultra-wide spectrum color separation, which not only satisfies the color separation of visible light and infrared light, but also satisfies the fine color separation of infrared light, and can be applicable to a wider range of application scenarios.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown, the multi-spectrum ultra-wide spectrum color separation prism provided by the present invention includes prism A, prism B, and prism C. The prism A, prism B, and prism C are all triangular prisms. The prism A, prism B, and prism C all have an incident surface, an exit surface, and a color separation surface for light. The color separation surface of the prism A is adjacent to the incident surface of the prism B, and the color separation surface of the prism B is adjacent to the incident surface of the prism C.

[0036] The dichroic surface of the prism A is coated with a dichroic film S1, so that visible light is reflected and infrared light is transmitted. The visible light is totally reflected at the incident surface of the prism A to form an output light 1, which is emitted from the output surface of the prism A. The dichroic characteristics of the dichroic film S1 are: R>95%@0.4-0.7um, T>99%@0.85-1.65um&@3-5um&@8-12um; wherein R represents reflectivity and T represents transmittance.

[0037] The dichroic surface of the prism B is coated with a dichroic film S2, so that short-wave infrared light is reflected and medium-wave and long-wave infrared light is transmitted. The short-wave infrared light is totally reflected at the incident surface of the prism B to form an output light 2, which is emitted from the output surface of the prism B. The dichroic characteristics of the dichroic film S2 are: R>95%@0.85-1.65um, T>99%@3-5um&@8-12um;

[0038] The dichroic surface of the prism C is coated with a dichroic film S3, so that the medium-wave infrared light is reflected to form the output light 3, and the long-wave infrared light is transmitted to form the output light 4. The output light 3 is emitted from the dichroic surface of the prism C, and the output light 4 is emitted from the output surface of the prism C; the dichroic characteristics of the dichroic film S3 are: R>95%@3-5um, T>99%@8-12um.

[0039] The dichroic films correspond to different wavelengths of light, visible light (wavelength 0.4-0.7um) and infrared light. Infrared light can be divided into short-wave infrared light (wavelength 0.85-1.65um), medium-wave infrared light (wavelength 3-5um), and long-wave infrared light (wavelength 8-12um).

[0040] The prism A and the prism B, and the prism B and the prism C are combined together by air gap bonding. The present invention preferably uses air gap bonding to avoid the problem of large infrared absorption of glue.

[0041] The materials of the prism A, prism B and prism C are preferably materials that do not absorb visible light and applied spectrum, for example, ZNS (zinc sulfide), ZNSE (zinc selenide), BAF2 (barium fluoride), etc., and multi-spectrum ZNS is preferred.

[0042] The angles between the incident surface of the prism A and the color separation surface and the exit surface are θ1 and θ2 respectively, the angles between the incident surface of the prism B and the color separation surface and the exit surface are θ4 and θ3 respectively, and the angles between the color separation surface of the prism C and the incident surface and the exit surface are θ5 and θ6 respectively, wherein the degrees of each angle are θ1=θ6, θ2=θ3=θ4=θ5.

[0043] The total reflection angle of the prism A is θ 反 , 2*θ1 and θ2 are greater than θ 反 The total reflection angle of the prism A is determined by the refractive index of the material. For example, if the multi-spectral ZNS material (refractive index n=2.4) is used as the prism material, according to the calculation formula of the total reflection angle sinθ=1 / n, it can be easily calculated that the total reflection angle of the multi-spectral ZNS is 24.6 degrees, that is, 2*θ1 and θ2 are greater than 25 degrees to achieve the total reflection effect. These two angles are the angles of the light on the total reflection surface, which are greater than the total reflection angle.

[0044] Example

[0045] The present invention takes ZNS material (refractive index n=2.4) as an example of prism material to further illustrate the specific structure of the multi-spectrum ultra-wide spectrum color separation prism:

[0046] Among them, 2*θ1 and θ2 are greater than 25 degrees; according to Figure 1In the optical path diagram shown, θ1=θ6=20 degrees, θ2=θ3=θ4=θ5=40 degrees;

[0047] The S1 surface of prism A is coated with a dichroic film S1 (R>95%@0.4-0.7um, T>99%@0.85-1.65um&@3-5um&@8-12um, 20 degree ZNS incident), so that visible light is reflected and infrared light is transmitted; the visible light is totally reflected at the incident surface of prism A to form output light 1.

[0048] The S2 surface of prism B is coated with a dichroic film S2 (R>95%@0.85-1.65um, T>99%@3-5um&@8-12um, 20 degree ZNS incidence), so that short-wave infrared light is reflected and medium-wave and long-wave infrared light is transmitted; the short-wave infrared light is totally reflected by the S1 surface of prism B to form output light 2.

[0049] The S3 surface of the prism C is coated with a dichroic film S3 (R>95%@3-5um, T>99%@8-12um, 20 degree ZNS incidence), so that the medium-wave infrared light is reflected to form the output light 3; and the long-wave infrared light is transmitted to form the output light 4.

[0050] The non-dichroic surface of each prism can be coated with an anti-reflection film of the corresponding wavelength to reduce reflection loss and increase transmittance.

[0051] The prisms A, B and C are combined together by combining the S1 surface and the S2 surface through an air gap, and an air gap of about 10um is formed at the interface of the two prisms using micro beads, micro gaskets or other forms.

[0052] Optical path description of multi-spectral ultra-wide spectrum dichroic prism:

[0053] After passing through prism A, the incident light is separated into visible light and infrared light, and the visible light is totally reflected to form output light 1; after passing through prism B, the transmitted infrared light is separated into short-wave infrared light and medium-wave + long-wave infrared light, and the short-wave infrared light is totally reflected to form output light 2; after passing through prism C, the transmitted medium-wave + long-wave infrared light is separated into medium-wave infrared light and long-wave infrared light, and the medium-wave infrared light is reflected to form output light 3, while the long-wave infrared light is transmitted to form output light 4. Finally, the incident light is finely separated into visible light, short-wave infrared light, medium-wave infrared light, and long-wave infrared light.

[0054] The present invention also provides a method for processing a multi-spectrum ultra-wide spectrum color separation prism, which is applied to the multi-spectrum ultra-wide spectrum color separation prism, and comprises the following steps:

[0055] Three prisms are processed by optical cold processing, namely prism A, prism B, and prism C, and the surfaces of the three prisms are polished. The finish of the optical surface of each prism is better than S / D=60 / 40;

[0056] The dichroic surface of prism A is coated with a dichroic film S1 to reflect visible light and transmit infrared light;

[0057] A dichroic film S2 is coated on the dichroic surface of prism B to reflect short-wave infrared light and transmit medium-wave and long-wave infrared light;

[0058] A dichroic film S3 is coated on the dichroic surface of the prism C to reflect the mid-wave infrared light and transmit the long-wave infrared light;

[0059] The incident and exit surfaces of prism A, prism B and prism C are coated with anti-reflection films of corresponding wavelengths;

[0060] The color separation surface of prism A and the incident surface of prism B, as well as the color separation surface of prism B and the incident surface of prism C are combined together by air gaps. The air gaps are formed by using materials such as micro beads or micro gaskets at the interface between adjacent prisms to form an air gap of about 10um.

[0061] In summary, the multi-spectrum ultra-wide spectrum color separation prism provided by the embodiment of the present invention realizes four color separations with three prisms. The three prisms all adopt an air gap combination solution, which completely avoids the problem of large infrared absorption of industry glue. In ultra-wide spectrum applications, the color separation prism not only meets the color separation of visible light and infrared light, but also meets the fine color separation of infrared light, and can be suitable for a wider range of application scenarios.

[0062] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A multi-spectral ultra-wide spectrum color separation prism, characterized in that: Comprising prism A, prism B and prism C, wherein prism A, prism B and prism C are all triangular prisms, and each of prism A, prism B and prism C has an incident surface, an exit surface and a color separation surface for light, the color separation surface of prism A is adjacent to the incident surface of prism B, and the color separation surface of prism B is adjacent to the incident surface of prism C; The dichroic surface of the prism A is coated with a dichroic film S1, which reflects visible light and transmits infrared light. The visible light is totally reflected at the incident surface of the prism A to form an output light 1, which is emitted from the output surface of the prism A. The dichroic surface of the prism B is coated with a dichroic film S2, so that short-wave infrared light is reflected and medium-wave and long-wave infrared light are transmitted. The short-wave infrared light is totally reflected at the incident surface of the prism B to form an output light 2, which is emitted from the output surface of the prism B. The dichroic surface of the prism C is coated with a dichroic film S3, so that the medium-wave infrared light is reflected to form the output light three, and the long-wave infrared light is transmitted to form the output light four. The output light three is emitted from the dichroic surface of the prism C, and the output light four is emitted from the output surface of the prism C.

2. The multi-spectral ultra-wide spectrum color separation prism according to claim 1, characterized in that: The prism A and the prism B, and the prism B and the prism C are combined together by an air gap.

3. The multi-spectral ultra-wide spectrum color separation prism according to claim 1, characterized in that: The materials of the prism A, prism B and prism C are ZNS, ZNSE or BAF2.

4. The multi-spectral ultra-wide spectrum color separation prism according to claim 1, characterized in that: The angles between the incident surface of the prism A and the color separation surface and the exit surface are θ1 and θ2 respectively, the angles between the incident surface of the prism B and the color separation surface and the exit surface are θ4 and θ3 respectively, and the angles between the color separation surface of the prism C and the incident surface and the exit surface are θ5 and θ6 respectively, wherein the degrees of each angle are θ1=θ6, θ2=θ3=θ4=θ5.

5. The multi-spectral ultra-wide spectrum color separation prism according to claim 4, characterized in that: The total reflection angle of the prism A is θ 反 , 2*θ1 and θ2 are greater than θ 反 .

6. The multi-spectral ultra-wide spectrum color separation prism according to claim 1, characterized in that: The color separation characteristics of the color separation film S1 are: R>95%@0.4-0.7um, T>99%@0.85-1.65um&@3-5um&@8-12um; The color separation characteristics of the color separation film S2 are: R>95%@0.85-1.65um, T>99%@3-5um&@8-12um; The color separation characteristics of the color separation film S3 are: R>95%@3-5um, T>99%@8-12um; Wherein, R represents reflectivity and T represents transmittance.

7. The multi-spectral ultra-wide spectrum color separation prism according to claim 1, characterized in that: The incident surfaces and the exit surfaces of the prism A, the prism B and the prism C are coated with anti-reflection films.

8. A method for processing a multi-spectrum ultra-wide spectrum color separation prism, applied to prepare the multi-spectrum ultra-wide spectrum color separation prism according to any one of claims 1 to 7, comprising the following steps: Three prisms are processed by optical cold processing, namely prism A, prism B, and prism C, and the surfaces of the three prisms are polished. The finish of the optical surface of each prism is better than S / D=60 / 40; The dichroic surface of prism A is coated with a dichroic film S1 to reflect visible light and transmit infrared light; A dichroic film S2 is coated on the dichroic surface of prism B to reflect short-wave infrared light and transmit medium-wave and long-wave infrared light; A dichroic film S3 is coated on the dichroic surface of the prism C to reflect the mid-wave infrared light and transmit the long-wave infrared light; The incident surface and the exit surface of prism A, prism B and prism C are respectively coated with anti-reflection films; The color separation surface of prism A and the incident surface of prism B, and the color separation surface of prism B and the incident surface of prism C are combined together by air gaps.

9. The method for processing a multi-spectrum ultra-wide spectrum color separation prism according to claim 8, characterized in that: The air gap is a 10 um air gap formed at the bonding interface of adjacent prisms by using micro beads or micro gaskets.

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