Spectroscope and preparation method thereof

Abstract

The invention relates to an optical product, in particular to a spectroscope and a preparation method thereof, and aims at solving the problems that an existing spectroscope is narrow in working spectral range, large in absorption of a light splitting film layer, large in stress, low in film layer reliability and the like. The spectroscope comprises a Ge substrate, a beam splitting film plated on the front surface of the Ge substrate and an antireflection film plated on the rear surface of the Ge substrate. The preparation method of the spectroscope comprises the following steps: 1) respectively carrying out film system design on the light splitting film and the antireflection film to obtain design data; 2) wiping and cleaning the front surface of the Ge substrate; 3) plating a light splitting film; 4) testing the performance of the light splitting film; 5) wiping and cleaning the rear surface of the Ge substrate; 6) performing surface type correction on the Ge substrate with the beam splitting film; 7) wiping and cleaning the rear surface of the Ge substrate; 8) plating an antireflection film; 9) testing the performance of the antireflection film; and 10) carrying out an adhesive force test, an anti-friction test and a damp heat test on the spectroscope.

Description

Technical Field

[0001] The present invention relates to an optical product, and more particularly to a beam splitter and a preparation method thereof. Background Art

[0002] At present, the development of optoelectronic technology equipment is getting updated day by day. Therefore, the industry has higher and higher requirements for the structural compactness, operation simplicity and error tolerance of optoelectronic technology equipment. The developed multi-spectral common optical path and common window technology can meet the needs of modern information technology, which is the general trend. It integrates spectral regions such as visible light, short-wave infrared, mid-wave infrared, and long-wave infrared for comprehensive application to form an optical system of "multiple lights in one" to achieve the advanced working technical requirements of highly integrated multi-functional machines. The beam splitter is the core component of the "multiple lights in one" system, and its performance directly determines the function and quality of the system.

[0003] Currently, the work in this area is in full swing, but most of it focuses on the research of beam splitting films for the common optical path of three spectral bands of visible light, 1.06 μm laser, 1.57 μm laser and mid-infrared light, that is, the "three lights in one". However, the widest infrared atmospheric window is hardly utilized. The water absorption in this spectral band is small, and the transmittance is about 80%, which is a good infrared thermal imaging spectral band. If it can be used, the technical requirement of "all-weather" work can be truly achieved.

[0004] The prior art mostly uses the method of multi-stage color separation to efficiently separate optical signals to meet the full spectral band response of detectors. Using a beam splitting film with high surface accuracy requirements that is anti-visible and transmits infrared in a large field of view and long focal length optical path system can greatly simplify the optical path structure and improve the imaging quality, which can be achieved by tilting the long-wave pass filter of the all-dielectric film system. The difficulty is that the coating materials are required to have high transmittance performance in both visible and infrared regions. Currently available materials have varying degrees of absorption in the visible region, resulting in a decrease in reflectivity. In addition, due to the relatively wide working spectral range of the reflection region, multiple reflection stacks have to be used to expand the bandwidth, and the number of film layers and the total thickness will inevitably increase exponentially. Since most infrared materials have large stresses, as the number of layers increases and the thickness increases, the stress increases and the reliability decreases. If simultaneous wide-spectrum transmission in the mid- and far-infrared is to be achieved, the research and development difficulty will be further increased. For infrared antireflection films for space applications, in addition to ensuring high optical efficiency, the reliability and space adaptability of the film layers also need to be considered.

[0005] Therefore, it is very necessary to carry out research on the preparation process of beam splitting films for "four lights in one" of visible light, short-wave infrared, mid-wave infrared, and mid-wave infrared. From Figure 1It can be seen that the first beam splitter 4 is used to reflect visible light and short-wave infrared and transmit medium-wave and long-wave infrared; the second beam splitter 5 is used to reflect medium-wave infrared and transmit long-wave infrared; the third beam splitter 6 is used to reflect visible light and transmit short-wave infrared. The first beam splitter 4 transmits medium-wave and long-wave infrared and reflects visible light and short-wave infrared. The bandwidths of the reflection band and the transmission band are relatively wide, and the process implementation is difficult. Therefore, the relevant field mainly focuses on the research of the preparation of the first beam splitter 4. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems of narrow working spectral range of the existing beam splitter, large absorption of the beam splitting film layer, large stress, and low reliability of the film layer, and to provide a beam splitter and a preparation method thereof.

[0007] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0008] A beam splitter, characterized in that:

[0009] It includes a Ge substrate, a beam splitting film plated on the front surface of the Ge substrate, and an antireflection film plated on the back surface of the Ge substrate; the beam splitting film includes six film stacks from near to far from the front surface of the Ge substrate. The i-th film stack includes T i the i-th film set arranged in layers in sequence, i = 1 to 6, T i = 8 to 10, both i and T i are integers;

[0010] Each of the first film sets includes two Ge layers with an optical thickness of λ1 / 8, and a ZnS layer with an optical thickness of λ1 / 4 arranged between the two Ge layers; each of the second film set, the third film set, the fourth film set, the fifth film set, and the sixth film set includes two ZnS layers with an optical thickness of λ1 / 8, and a YbF3 layer with an optical thickness of λ1 / 4 arranged between the two ZnS layers; where λ1 is the central wavelength of the beam splitting film;

[0011] The antireflection film includes ten layers with an optical thickness of λ2 / 4 from near to far from the back surface of the Ge substrate, which are the first layer to the tenth layer in sequence, and are a ZnS layer, a Ge layer, a ZnS layer, a Ge layer, a ZnS layer, a YbF3 layer, a Ge layer, a YbF3 layer, a Ge layer, and a YbF3 layer respectively, where λ2 is the central wavelength of the antireflection film.

[0012] Furthermore, λ1 = 1700nm to 1900nm; λ2 = 700 to 900nm.

[0013] Furthermore, the thickness h Ge0 of the Ge substrate = 2mm;

[0014] The total thickness sum h of all Ge layers in the first film stackG1 = 850 - 1125 nm;

[0015] The total thickness h of all ZnS layers in the first film stack Z1 = 1580 - 2020 nm;

[0016] The total thickness h of all ZnS layers in the second film stack Z2 = 1268 - 1615 nm;

[0017] The total thickness h of all ZnS layers in the third film stack Z3 = 1000 - 1278;

[0018] The total thickness h of all ZnS layers in the fourth film stack Z4 = 777 - 1030 nm;

[0019] The total thickness h of all ZnS layers in the fifth film stack Z5 = 654 - 700 nm;

[0020] The total thickness h of all ZnS layers in the sixth film stack Z6 = 492 - 609 nm;

[0021] The total thickness h of all YbF3 layers in the second film stack Y1 = 1930 - 2454 nm;

[0022] The total thickness h of all YbF3 layers in the third film stack Y2 = 1520 - 1940 nm;

[0023] The total thickness h of all YbF3 layers in the fourth film stack Y3 = 1182 - 1564 nm;

[0024] The total thickness h of all YbF3 layers in the fifth film stack Y4 = 993 - 1345 nm;

[0025] The total thickness h of all YbF3 layers in the sixth film stack Y5 = 750 - 925 nm.

[0026] Furthermore, the physical thickness h1 of the first layer in the ten-layer film = 35 - 47 nm;

[0027] The physical thickness h2 of the second layer in the ten-layer film = 129 - 168 nm;

[0028] The physical thickness h3 of the third layer in the ten-layer film = 122 - 160 nm;

[0029] The physical thickness h4 of the fourth layer in the ten-layer film = 81 - 107 nm;

[0030] The physical thickness h5 of the fifth layer in the ten-layer film is 169 - 220 nm;

[0031] The physical thickness h6 of the sixth layer in the ten-layer film is 105 - 138 nm;

[0032] The physical thickness h7 of the seventh layer in the ten-layer film is 57 - 75 nm;

[0033] The physical thickness h8 of the eighth layer in the ten-layer film is 370 - 480 nm;

[0034] The physical thickness h9 of the ninth layer in the ten-layer film is 30 - 39 nm;

[0035] The physical thickness h of the tenth layer in the ten-layer film 10 = 823 - 1063 nm.

[0036] Further, T1 = 9, T2 = 8, T3 = 8, T4 = 8, T5 = 9, T6 = 9.

[0037] Meanwhile, the present invention also provides a method for preparing the above spectroscope, which is characterized in that it includes the following steps:

[0038] Step 1: Prepare a Ge substrate, measure and obtain the RMS1 value of the front surface profile of the Ge substrate, and then, according to actual requirements, perform film stack design on the spectroscopic film and the antireflection film respectively to obtain design data, where the design data includes the total thickness h G1 of all Ge layers in the first film stack of the spectroscopic film, the total thickness h Zi of all ZnS layers in the first to sixth film stacks, the total thickness h Yj of all YbF3 layers in the second to sixth film stacks, the physical thickness h k of the ten-layer film in the antireflection film, and the baking temperature, deposition rate, anode voltage of the ion source, and cathode current parameters during the preparation of the spectroscopic film and the antireflection film;

[0039] Step 2: Wipe and clean the front surface of the Ge substrate, then place the front surface of the Ge substrate downward into the coating tooling, and clamp the coating tooling onto the workpiece disk in the coating chamber;

[0040] Step 3: Evacuate the inside of the coating chamber; input the design data obtained in Step 1 into the coating program of the spectroscopic film, and then start coating. The workpiece disk starts to rotate, and the film thickness controller controls the thickness of each layer of film. The rotation speed of the workpiece disk is r1 = 10 - 20 r / min, and the baking temperature is T 01 = 100 - 120 °C;

[0041] Step 4: After the preparation of the beam-splitting film, check the surface appearance of the film layer on the front surface of the Ge substrate with the beam-splitting film, and test the visible-short wave infrared reflectivity and mid-long wave infrared transmittance of the beam-splitting film; if the test is qualified, measure the surface shape RMS2 value from the front surface direction of the Ge substrate, and then execute Step 5; if cracks or peeling occur on the appearance film layer, or at least one of the reflectivity and transmittance is unqualified, discard the Ge substrate with the beam-splitting film, return to Step 1, and optimize at least one parameter in the design data;

[0042] Step 5: Wipe and clean the back surface of the Ge substrate, then place the back surface of the Ge substrate downward into the coating tooling, and clamp the coating tooling onto the workpiece disk in the coating chamber;

[0043] Step 6: Evacuate the inside of the coating chamber;

[0044] Step 7: Use the deposition rate, anode voltage and cathode current parameters obtained in Step 1, and the RMS2 value obtained in Step 4 to perform surface shape correction on the Ge substrate with the beam-splitting film, and obtain the surface shape correction data RMS5 value;

[0045] Step 8: Execute Step 5 again;

[0046] Step 9: Evacuate the inside of the coating chamber; use the surface shape correction data RMS5 value obtained in Step 7 to correct the design data obtained in Step 1, input the corrected design data into the coating program of the anti-reflection film 3, and then start coating. The workpiece disk starts to rotate, and the film thickness controller controls the thickness of each layer of the film. The rotation speed of the workpiece disk is r2 = 10 - 20 r / min, and the baking temperature is T 02 = 100 - 120 °C;

[0047] Step 10: After the preparation of the anti-reflection film is completed, obtain the beam splitter and test the mid-long wave infrared transmittance of the beam splitter; if the test is qualified, execute Step 11; if the test is unqualified, discard the beam splitter, return to Step 1, and optimize at least one parameter in the design data;

[0048] Step 11: Conduct adhesion test, anti-friction test and damp heat test on the prepared beam splitter; if all three tests are qualified, determine that the beam splitter is qualified and the preparation is completed; if at least one of the three tests is unqualified, determine that the beam splitter is unqualified, discard the beam splitter prepared this time, and return to Step 1 to re-prepare.

[0049] Further, Step 7 is specifically:

[0050] Step 7.1: Edit the film system program of the single-layer Ge film, the first evaporation temperature T 03 = 90 - 110 °C, the first deposition rate is The anode voltage and cathode current parameters of the ion source are 100 V / 1 A, and the thickness h of the first Ge single-layer film is calculated using the RMS2 value. Ge-1 , and then a Ge single-layer film with a thickness of h Ge-1 is deposited on the back surface of the Ge substrate, where h Ge-1 = 120 - 1200 nm;

[0051] Step 7.2: After the deposition of the Ge single-layer film with a thickness of h Ge-1 is completed, the surface profile RMS3 value of the Ge substrate is measured from the front surface direction of the Ge substrate;

[0052] Step 7.3: Steps 5 and 6 are executed again to edit the film system program of the single-layer Ge film. The second evaporation temperature T 04 = 90 - 110 °C, and the second deposition rate The anode voltage and cathode current parameters of the ion source are 100 V / 1 A, and the thickness h of the second Ge single-layer film is calculated using the RMS3 value. Ge-2 , and then a Ge single-layer film with a thickness of h Ge-2 is deposited on the back surface of the Ge substrate, where h Ge-2 = 0 - 660 nm;

[0053] Step 7.4: After the deposition of the Ge single-layer film with a thickness of h Ge-2 is completed, the surface profile RMS4 value of the Ge substrate is measured from the front surface direction of the Ge substrate;

[0054] Step 7.5: Steps 5 and 6 are executed again to edit the film system program of the single-layer Ge film. The third evaporation temperature T 05 = 90 - 110 °C, and the third deposition rate The anode voltage and cathode current parameters of the ion source are 100 V / 1 A, and the thickness h of the third Ge single-layer film is calculated using the RMS4 value. Ge-3 , and then a Ge single-layer film with a thickness of h Ge-3 is deposited on the back surface of the Ge substrate, where h Ge-3 = 0 - 360 nm;

[0055] Step 7.6: After the deposition of the Ge single-layer film with a thickness of h Ge-3 is completed, the RMS5 value of the surface profile of the Ge substrate is measured from the front surface direction of the Ge substrate.

[0056] Furthermore, step 11 is specifically as follows:

[0057] Step 11a: Perform an adhesion test on the beam splitter

[0058] Use an adhesive strength greater than 3 N·cm -2The tape is closely attached to the front surface of the Ge substrate in the spectroscope, and then it is vertically pulled up along the surface of the spectroscopic film layer at a pulling speed of 25 mm / s. Check whether there are any peeling traces on the surface of the spectroscopic film under reflected light; if there are no peeling traces and step 11c has not been performed, then perform step 11b; if there are no peeling traces and step 11c has been performed, then determine that the adhesion test of the spectroscope is qualified and the preparation is completed; if there are peeling traces, then determine that the spectroscope is unqualified, discard the spectroscope prepared this time, and then return to step 1 to re-perform the preparation;

[0059] Step 11b: Conduct an anti-friction test on the spectroscope

[0060] Use absorbent cotton gauze to reciprocally rub on the surface of the spectroscopic film layer 25 times, and check for physical damage traces on the surface of the spectroscopic film under reflected light; if there are no physical damage traces, then determine that the anti-friction test of the spectroscope is qualified, and then perform step 11c; if there are physical damage traces, then determine that the spectroscope is unqualified, discard the spectroscope prepared this time, and then return to step 1 to re-perform the preparation;

[0061] Step 11c: Conduct a damp heat test on the spectroscope

[0062] Expose the spectroscope to the atmosphere with a relative humidity of 90% and a temperature of 55°C ± 2°C for 16 hours, with the front surface direction of the Ge substrate facing upwards, and then use a spectrophotometer to test the reflectivity and transmittance of the spectroscope; if both the reflectivity and transmittance meet the actual requirements, then determine that the damp heat test of the spectroscope is qualified, and then return to perform step 11a; if at least one of the reflectivity and transmittance is unqualified, then determine that the spectroscope is unqualified, discard the spectroscope prepared this time, and then return to step 1 to re-perform the preparation.

[0063] Furthermore, in steps 1, 4, 7, and 10, the device used to measure the surface profile of the Ge substrate is a Zygo interferometer;

[0064] In steps 2, 3, 5, 6, 8, and 9, the coating chamber is a ZZS1100 infrared vacuum coating chamber;

[0065] In step 4, the visible-short wave infrared reflectivity and mid-long wave infrared transmittance of the spectroscopic film are tested, and in step 10, the device used to test the mid-long wave infrared transmittance of the spectroscope is a spectrophotometer;

[0066] In steps 2 and 5, the tools used to wipe and clean the front and back surfaces of the Ge substrate are absorbent cotton dipped in a mixed solution of anhydrous ethanol and ether, where the volume ratio of anhydrous ethanol to ether is 3:1;

[0067] Step 2 further includes: using a strong light to check whether there is dust on the front surface of the Ge substrate, and if there is dust, using an ear syringe to clean it;

[0068] Step 5 further includes: using a strong light to check whether there is dust on the back surface of the Ge substrate, and if there is dust, using an ear syringe to clean it.

[0069] Further, in step 3, r1 = 15 r / min, T 01 = 100 °C;

[0070] In step 9, r2 = 15 r / min, T 02 = 100 °C;

[0071] In step 7.1, T 03 = 100 °C, h Ge-1 = 200 nm;

[0072] In step 7.3, T 04 = 100 °C, h Ge-2 = 650 nm;

[0073] In step 7.5, T 05 = 100 °C, h Ge-3 = 150 nm.

[0074] Compared with the prior art, the beneficial effects of the present invention are:

[0075] 1. The beam splitter provided by the present invention has the function of full-spectrum response, and its working wavelength takes into account visible light, short-wave infrared light, mid-wave infrared light, and long-wave infrared light; when it is applied to an optical system, it can greatly simplify the structure of the optical path system and meet the actual use requirements of advanced optoelectronic devices;

[0076] 2. For the beam splitter provided by the present invention, the beam splitting film on the upper surface of the Ge substrate is alternately deposited with three high, medium, and low refractive index materials of Ge, ZnS, and YbF3. ZnS and YbF3 have good transparency and small absorption in the visible light region and the infrared light region, and the ZnS / YbF3 film stack can achieve high reflection characteristics for visible light and short-wave infrared. The semiconductor material Ge has excellent infrared optical and physical properties and an extremely high refractive index. Therefore, Ge is combined with ZnS in the range of 1.7 μm to 23 μm, and the refractive index difference between the two materials is large. The Ge / ZnS film stack combination can achieve high transmission characteristics for mid-wave infrared and long-wave infrared while reducing the number of film layers, and the beam transmission efficiency is high;

[0077] 3. The beam splitter provided by the present invention has an average reflectivity of more than 86% in the visible band on its upper surface splitter film, an average reflectivity of more than 92% in the short-wave infrared range, and an average transmittance of both sides of more than 90% in the mid-wave infrared and long-wave infrared ranges;

[0078] 4. For the beam splitter provided by the present invention, the surface shape of the Ge substrate remains unchanged before and after coating. The biggest difficulty is that the relatively thick thickness of the front surface splitter film will inevitably cause a large change in the surface shape of the Ge substrate before and after coating the splitter film. By adopting a surface shape control technology on the back surface of the Ge substrate, establishing a surface shape correction model, and gradually improving the surface shape by calculating and depositing corresponding film layers, the surface shape accuracy after coating is successfully kept unchanged. The beam splitter with high surface shape accuracy can avoid beam divergence and defocus, ensuring the stability of beam quality and transmission reliability during actual application, thereby minimizing losses;

[0079] 5. The anti-reflection film on the lower surface of the beam splitter provided by the present invention is alternately deposited with three materials of Ge, ZnS, and YbF3 with high, medium, and low refractive indices. The refractive index difference is large. In the design of the multi-layer anti-reflection film, the Ge film is used to reduce the reflection loss and reduce the number of film layers. Only ten layers are required to meet the high transmittance characteristics in the mid-wave infrared and long-wave infrared, and it is in a relatively low stress state;

[0080] 6. The single-sided average transmittance of the anti-reflection film on the lower surface of the beam splitter provided by the present invention can reach more than 96% in the two bands of mid-wave infrared and long-wave infrared, improving the beam transmission efficiency;

[0081] 7. In the preparation method of the beam splitter provided by the present invention, after the adhesion test of the splitter film, no traces such as peeling are observed on the surface of the film layer with the naked eye under the reflected light. The adhesion between the film layer and the substrate is good, and it has high mechanical properties and can be directly applied to optoelectronic instruments;

[0082] 8. In the preparation method of the beam splitter provided by the present invention, after the friction test of the splitter film, no scratches or film peeling are observed on the surface of the film layer with the naked eye under the reflected light. The film layer has excellent anti-friction performance and can be directly applied to optoelectronic instruments;

[0083] 9. In the preparation method of the beam splitter provided by the present invention, no wrinkling, cracking, peeling, etc. occur on the surface of the film layer after humidity and heat treatment. The film layer has good environmental tolerance, can adapt to a humid environment, and can be directly applied to optoelectronic devices; BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 It is a schematic optical path diagram of the prior art "four-in-one" system;

[0085] Figure 2 It is a schematic diagram of an embodiment of the beam splitter of the present invention;

[0086] Figure 3 Flow chart of the preparation method of the beam splitter of the present invention

[0087] Figure 4 Graph of the relationship between the refractive indices of three materials, Ge, ZnS, and YbF3, and the wavelength of incident light

[0088] Figure 5 Designed spectrum of the beam splitting film in the beam splitter of the first embodiment of the present invention

[0089] Figure 6 Designed spectrum of the antireflection film in the beam splitter of the first embodiment of the present invention

[0090] Figure 7 Measured curve of visible to short-wave infrared reflection of the beam splitting film in the beam splitter of the first embodiment of the present invention

[0091] Figure 8 Measured curve of mid- and long-wave infrared transmission of the beam splitting film in the beam splitter of the first embodiment of the present invention

[0092] Figure 9 Measured curve of mid- and long-wave infrared transmission of the antireflection film in the beam splitter of the first embodiment of the present invention

[0093] Explanation of reference numerals

[0094] 1 - Ge substrate, 11 - front surface, 12 - rear surface, 2 - beam splitting film, 3 - antireflection film, 4 - first beam splitter, 5 - second beam splitter, 6 - third beam splitter Detailed implementation manners

[0095] The present invention will be further described below in conjunction with the accompanying drawings and five specific embodiments. Currently, the research and development of beam splitters mainly focus on splitting short-wave infrared and mid- and long-wave infrared. There is no report on a beam splitter that combines visible light band, short-wave infrared, mid-wave infrared, and long-wave infrared. Such a "four-in-one" spectral color separation method can greatly simplify the structure of the optical path system and improve the imaging quality. The difficulty lies in minimizing the coating difficulty of the beam splitter while ensuring the splitting efficiency, reducing the large cumulative error of film thickness control caused by problems such as a large number of layers and thick film layers, which results in poor spectral reflection / transmission of the beam splitting film. In addition, a beam splitter with high surface accuracy can ensure the stability of the beam transmission process and improve the reliability of the optical system. Therefore, the present invention provides an ultra-wide spectral beam splitting film and a preparation method, which enable the effective integration and comprehensive application of visible light, short-wave infrared, mid-wave infrared, and long-wave infrared, and obtain a "four-in-one" beam splitter with visible-near infrared reflection and mid- and far-infrared transmission

[0096] Embodiment 1

[0097] The beam splitter provided by the present invention has the function of full-spectrum response, and its working wavelength covers visible light: 0.5 - 0.8μm, short-wave infrared: 0.9 - 1.7μm, mid-wave infrared: 3 - 5μm, and long-wave infrared: 8 - 12μm. As Figure 1 shown in the schematic diagram of the "four-in-one" optical path system of the prior art. From Figure 1 it can be seen that the second beam splitter 5 reflects mid-wave infrared and transmits long-wave infrared; the third beam splitter 6 reflects visible light and transmits short-wave infrared. The first beam splitter 4 reflects visible light and short-wave infrared, transmits mid-wave infrared and long-wave infrared, and the bandwidths of the reflection band and the transmission band are both relatively wide, making it difficult to achieve in terms of technology. Therefore, the beam splitter provided by the present invention is applied to Figure 1 the first beam splitter 4 in the "four-in-one" optical path system of Figure 2 The schematic diagram of the embodiment of the beam splitter of the present invention shows that double-sided coating is carried out on a Ge substrate, a beam splitting film is deposited on the upper surface, and an antireflection film is deposited on the lower surface.

[0098] A beam splitter, see Figure 2 ; It includes a Ge substrate 1, a beam splitting film 2 deposited on the front surface 11 of the Ge substrate 1, and an antireflection film 3 deposited on the rear surface 12 of the Ge substrate 1; the beam splitting film 2 includes six film stacks from near to far from the front surface of the Ge substrate 1. The i-th film stack includes T i the i-th first film set stacked in sequence, i = 1 - 6, T i = 8 - 10, both i and T i are integers; in this embodiment, T1 = 9, T2 = 8, T3 = 8, T4 = 8, T5 = 9, T6 = 9;

[0099] Each first film set includes two Ge layers with an optical thickness of λ1 / 8, and a ZnS layer with an optical thickness of λ1 / 4 disposed between the two Ge layers; each second film set, third film set, fourth film set, fifth film set, and sixth film set includes two ZnS layers with an optical thickness of λ1 / 8, and a YbF3 layer with an optical thickness of λ1 / 4 disposed between the two ZnS layers; where λ1 is the central wavelength of the beam splitting film 2, λ1 = 1800nm;

[0100] Define the thickness of the Ge substrate 1 as h Ge0 , the total thickness of all Ge layers in the first film stack is h G1 , the total thickness of all ZnS layers in the i-th film stack is h Zi , the total thickness of all YbF3 layers in the (j + 1)-th film stack is h Yj , i = 1 - 6, j = 1 - 5, where both i and j are integers;

[0101] The anti-reflection film 3 is arranged from near to far from the back surface of the Ge substrate 1 and includes ten layers of films with an optical thickness of λ2 / 4 each, which are the first layer to the tenth layer in sequence, and are a ZnS layer, a Ge layer, a ZnS layer, a Ge layer, a ZnS layer, a YbF3 layer, a Ge layer, a YbF3 layer, a Ge layer, and a YbF3 layer respectively, where λ2 is the central wavelength of the anti-reflection film 3, and λ2 = 800 nm; the physical thicknesses of the ten layers of films are defined as h k , k = 1 to 10, and k is an integer.

[0102] In this embodiment, the thickness h Ge0 of the Ge substrate 1 is 2 mm;

[0103] The total thickness h G1 of all Ge layers in the first film stack is 958.02 nm;

[0104] The total thickness h Z1 of all ZnS layers in the first film stack is 1787.24 nm;

[0105] The total thickness h Z2 of all ZnS layers in the second film stack is 1270.93 nm;

[0106] The total thickness h Z3 of all ZnS layers in the third film stack is 1000.86 nm;

[0107] The total thickness h Z4 of all ZnS layers in the fourth film stack is 778.44 nm;

[0108] The total thickness h Z5 of all ZnS layers in the fifth film stack is 697.02 nm;

[0109] The total thickness h Z6 of all ZnS layers in the sixth film stack is 554.05 nm;

[0110] The total thickness h Y1 of all YbF3 layers in the second film stack is 1932.99 nm;

[0111] The total thickness h Y2 of all YbF3 layers in the third film stack is 1522.23 nm;

[0112] The total thickness h Y3 of all YbF3 layers in the fourth film stack is 1183.96 nm;

[0113] The total thickness h Y4 of all YbF3 layers in the fifth film stack is 1060.12 nm;

[0114] The total thickness h of all YbF3 layers in the sixth membrane stack Y5 = 842.66 nm.

[0115] The physical thickness h1 of the first layer in the ten-layer film = 41.44 nm;

[0116] The physical thickness h2 of the second layer in the ten-layer film = 148.99 nm;

[0117] The physical thickness h3 of the third layer in the ten-layer film = 141.3 nm;

[0118] The physical thickness h4 of the fourth layer in the ten-layer film = 94.8 nm;

[0119] The physical thickness h5 of the fifth layer in the ten-layer film = 195.04 nm;

[0120] The physical thickness h6 of the sixth layer in the ten-layer film = 121.29 nm;

[0121] The physical thickness h7 of the seventh layer in the ten-layer film = 66.64 nm;

[0122] The physical thickness h8 of the eighth layer in the ten-layer film = 424.37 nm;

[0123] The physical thickness h9 of the ninth layer in the ten-layer film = 34.63 nm;

[0124] The physical thickness h of the tenth layer in the ten-layer film 10 = 943.63 nm.

[0125] Meanwhile, this embodiment also provides a method for manufacturing the above beam splitter. For its flowchart, see Figure 3 , including the following steps:

[0126] Step 1: Prepare a Ge substrate (1), measure and obtain the RMS1 value of the front surface (11) of the Ge substrate (1). Then, according to actual requirements, perform film system design on the beam splitting film (2) and the anti-reflection film (3) respectively to obtain design data, where the design data includes the total thickness h of all Ge layers in the first membrane stack of the beam splitting film (2) G1 , the total thickness h of all ZnS layers in the first to sixth membrane stacks Zi , the total thickness h of all YbF3 layers in the second to sixth membrane stacks Yj , the physical thickness h of the ten-layer film in the anti-reflection film (3) k , as well as the baking temperature, deposition rate, anode voltage of the ion source, and cathode current parameters during the manufacturing processes of the beam splitting film (2) and the anti-reflection film (3);

[0127] Step 2: Wipe and clean the front surface of the Ge substrate 1 with absorbent cotton dipped in a mixed solution of anhydrous ethanol and ether, where the volume ratio of anhydrous ethanol to ether is 3:1. Then place the front surface of the Ge substrate 1 downward into the coating tooling; transfer and clamp the coating tooling with the Ge substrate 1 onto the workpiece plate in the ZZS1100 infrared vacuum coating chamber;

[0128] Step 3: Close the door of the ZZS1100 infrared vacuum coating chamber, and then evacuate the inside of the ZZS1100 infrared vacuum coating chamber; edit the coating program of the beam splitting film 2 according to the design data obtained in Step 1, and then start coating. The workpiece plate starts to rotate, and the film thickness controller controls the thickness of each layer of the film. The rotation speed of the workpiece plate is r1 = 15 r / min, and the baking temperature is T 01 = 100 °C;

[0129] Step 3a: Use a strong light to check and clean whether there is dust on the front surface of the Ge substrate 1. If there is dust, use an ear syringe to clean it;

[0130] Step 4: After the beam splitting film 2 is prepared, place the front surface of the Ge substrate 1 with the beam splitting film 2 under an incandescent lamp to check the appearance of the film layer surface, and observe whether there are cracks or peeling of the film layer. Then use a spectrophotometer to test the visible-short wave infrared reflectivity and mid-long wave infrared transmittance of the beam splitting film 2; if the test is qualified, use a Zygo interferometer to measure the surface shape RMS2 value from the front surface direction of the Ge substrate 1, and then execute Step 5; if there are cracks or peeling in the film layer, or at least one of the reflectivity and transmittance is unqualified, discard the Ge substrate 1 with the beam splitting film 2, and then return to Step 1 to optimize at least one parameter in the design data and re-prepare the beam splitting film 2;

[0131] Step 5: Wipe and clean the back surface of the Ge substrate 1 with absorbent cotton dipped in a mixed solution of anhydrous ethanol and ether, where the volume ratio of anhydrous ethanol to ether is 3:1. Then place the back surface of the Ge substrate 1 downward into the coating tooling; transfer and clamp the coating tooling with the Ge substrate 1 onto the workpiece plate in the ZZS1100 infrared vacuum coating chamber;

[0132] Step 5a: Use a strong light to check and clean whether there is dust on the back surface of the Ge substrate 1. If there is dust, use an ear syringe to clean it;

[0133] Step 6: Close the door of the ZZS1100 infrared vacuum coating chamber, and then evacuate the inside of the ZZS1100 infrared vacuum coating chamber;

[0134] Step 7. Use the deposition rate, anode voltage, and cathode current parameters of the ion source obtained in Step 1, and the RMS2 value obtained in Step 2 to perform surface shape correction on the Ge substrate 1 with the spectroscopic film 2.

[0135] Step 7.1. Edit the film system program for the single-layer Ge film. The first evaporation temperature T 03 = 100 °C, and the first deposition rate is The anode voltage and cathode current parameters of the ion source are 100 V / 1 A. Calculate the thickness h Ge-1 of the first Ge single-layer film using the RMS2 value, and then deposit a Ge single-layer film with a thickness of h Ge-1 on the back surface of the Ge substrate 1 according to this process, where h Ge-1 = 500 nm;

[0136] Step 7.2. After the deposition of the Ge single-layer film with a thickness of h Ge-1 is completed, use a Zygo interferometer to measure the surface shape RMS3 value from the front surface direction of the Ge substrate 1.

[0137] Step 7.3. Repeat Steps 5 and 6. Edit the film system program for the single-layer Ge film. The second evaporation temperature T 04 = 100 °C, and the second deposition rate The anode voltage and cathode current parameters of the ion source are 100 V / 1 A. Calculate the thickness h Ge-2 of the second Ge single-layer film using the RMS3 value, and then deposit a Ge single-layer film with a thickness of h Ge-2 on the back surface of the Ge substrate 1 according to this process, where h Ge-2 = 650 nm;

[0138] Step 7.4. After the deposition of the Ge single-layer film with a thickness of h Ge-2 is completed, use a Zygo interferometer to measure the surface shape RMS4 value from the front surface direction of the Ge substrate 1.

[0139] Step 7.5. Repeat Steps 5 and 6. Edit the film system program for the single-layer Ge film. The third evaporation temperature T 05 = 100 °C, and the third deposition rate The anode voltage and cathode current parameters of the ion source are 100 V / 1 A. Calculate the thickness h Ge-3 of the third Ge single-layer film using the RMS4 value, and then deposit a Ge single-layer film with a thickness of h Ge-3 on the back surface of the Ge substrate 1 according to this process, where h Ge-3 = 150 nm;

[0140] Step 7.6. After the deposition of the Ge single-layer film with a thickness of h Ge-3After the deposition of the Ge single-layer film is completed, the RMS5 value of its surface profile is measured from the front surface direction of the Ge substrate 1 using a Zygo interferometer;

[0141] Step 8: Open the door of the ZZS1100 infrared vacuum coating chamber and repeat Step 5;

[0142] Step 9: Close the door of the ZZS1100 infrared vacuum coating chamber, and then evacuate the inside of the ZZS1100 infrared vacuum coating chamber; input the design data obtained in Step 1 and the RMS5 value of the surface profile correction data obtained in Step 7 into the coating program of the antireflection film 3, and then start coating. The workpiece disk starts to rotate, and the film thickness controller controls the thickness of each layer of the film. The rotation speed of the workpiece disk is r2 = 15 r / min, and the baking temperature is T 02 = 100 °C;

[0143] Step 10: After the antireflection film 3 is prepared, a spectroscope is obtained, and the RMS6 value of its surface profile is measured from the front surface direction of the Ge substrate 1. The value of |RMS6 - RMS1| is used as the surface profile error E, and then the transmittance of the mid- and long-wave infrared of the spectroscope is tested using an infrared spectrophotometer; if the test is qualified, Step 11 is executed; if the test is unqualified, the spectroscope is discarded, and then return to Step 1 to optimize at least one parameter in the design data and re-prepare the spectroscopic film 2;

[0144] Step 11: Conduct adhesion test, anti-friction test and damp heat test on the spectroscope specifically as follows:

[0145] Step 11a: Conduct adhesion test on the spectroscope

[0146] Use a tape with a viscosity strength greater than 3 N·cm -2 、a width of 1 inch, and a model of 3M610 to closely adhere to the front surface of the Ge substrate 1 in the spectroscope, and then vertically pull it up along the surface of the spectroscopic film 2 layer at a pulling speed of 25 mm / s. Visually inspect whether there are any peeling marks on the surface of the spectroscopic film 2 under reflected light; if there are no peeling marks and Step 11c has not been executed, Step 11b is executed; if there are no peeling marks and Step 11c has been executed, it is determined that the spectroscope test is qualified and the preparation is completed; if there are peeling marks, it is determined that the spectroscope test is unqualified, discard the spectroscope prepared this time, and then return to Step 1 to re-prepare;

[0147] Step 11b: Conduct anti-friction test on the spectroscope

[0148] Use absorbent cotton gauze to reciprocally rub the surface of the spectroscopic film 2 for 25 times, and visually inspect the physical damage marks on the surface of the spectroscopic film 2 under reflected light; if there are no physical damage marks, then execute step 11c; if there are physical damage marks, then determine that the spectroscope test is unqualified, discard the spectroscope prepared this time, and then return to step 1 to re-prepare.

[0149] Step 11c: Conduct a damp heat test on the spectroscope

[0150] Expose the spectroscope to the atmosphere with a relative humidity of 90% and a temperature of 55°C ± 2°C for 16 hours, and make the front surface direction of the Ge substrate 1 face upward, and then use a spectrophotometer to test the reflectivity and transmittance of the spectroscope; if both the reflectivity and transmittance meet the actual requirements, then return to execute step 11a; if at least one of the reflectivity and transmittance is unqualified, then determine that the spectroscope test is unqualified, discard the spectroscope prepared this time, and then return to step 1 to re-prepare.

[0151] It is known from Figure 4 that the refractive index of Ge is 4.4 (λ = 2μm), the refractive index of ZnS is 2.26 (λ = 2μm), and the refractive index of YbF3 is 1.48 (λ = 2μm). The refractive index curves of Ge, ZnS, and YbF3 can fully illustrate that the refractive indices of these materials are uniform and stable, conforming to the normal dispersion relationship distribution.

[0152] It is known from Figure 5 that the spectroscopic film spectral design results are: the average reflectivity in the range of 0.5 - 1.7μm is 98.72%, the average transmittance in the range of 3 - 5μm is 96.22%, and the average transmittance in the range of 8 - 12μm is 96.27%.

[0153] It is known from Figure 6 that the spectral design results of the antireflection film are: the average transmittance in the wavelength range of 3μm - 12μm is 97.34%.

[0154] It is known from Figure 7 that the spectroscopic mirror reflection spectrum test results are: at an incidence angle of 45°, the average reflectivity in the range of 0.5 - 0.8μm is 86.58%, and the average reflectivity in the range of 0.9 - 1.7μm is 93.7%.

[0155] It is known from Figure 8 that the transmission spectrum test results of the spectroscopic mirror with the spectroscopic film plated on the front surface and the antireflection film plated on the back surface are: at an incidence angle of 45°, the average transmittance in the range of 3 - 5μm is 91.36%, and the average transmittance in the range of 8 - 12μm is 91.29%.

[0156] It is known from Figure 9It can be known that the double-sided transmission spectrum test results of the antireflection film are as follows: incident at 45°, the average transmittance in the range of 3-5 μm is 62%, and the average transmittance in the range of 8-12 μm is 62.55%.

[0157] Example 2

[0158] The difference between the spectroscope in this example and that in Example 1 lies in that the parameters of the spectroscopic film 2 and the antireflection film 3 are not completely the same. The difference in the preparation method of the spectroscope lies in that the number of times of surface shape correction and the thickness of each correction are not completely the same. For the detailed content, please refer to the content in the third column of Tables 1-4.

[0159] Example 3

[0160] The difference between the spectroscope in this example and that in Example 1 lies in that the parameters of the spectroscopic film 2 and the antireflection film 3 are not completely the same. The difference in the preparation method of the spectroscope lies in that the number of times of surface shape correction and the thickness of each correction are not completely the same. For the detailed content, please refer to the content in the fourth column of Tables 1-4.

[0161] Example 4

[0162] The difference between the spectroscope in this example and that in Example 1 lies in that the parameters of the spectroscopic film 2 and the antireflection film 3 are not completely the same. The difference in the preparation method of the spectroscope lies in that the number of times of surface shape correction and the thickness of each correction are not completely the same. For the detailed content, please refer to the content in the fifth column of Tables 1-4.

[0163] Table 1 The repetition period number T of the i-th film set in each i-th film stack in all examples i Table

[0164] Example 1 Example 2 Example 3 Example 4 <![CDATA[T1]]> 9 8 10 9 <![CDATA[T2]]> 8 10 9 8 <![CDATA[T3]]> 8 10 9 9 <![CDATA[T4]]> 8 9 9 10 <![CDATA[T5]]> 9 8 10 8 <![CDATA[T6]]> 9 8 8 10

[0165] Table 2 The central wavelength table of the spectroscopic film and the antireflection film in all examples

[0166]

[0167]

[0168] Table 3 The thickness parameter table of the spectroscopic film and the antireflection film in all examples

[0169] Example 1 Example 2 Example 3 Example 4 <![CDATA[h G1 / nm]]> 958.02 852.52 1123.76 1011.25 <![CDATA[h Z1 / nm]]> 1787.24 1589.70 2096.95 1887.24 <![CDATA[h Z2 / nm]]> 1270.93 1612.2 1517.2 1342.04 <![CDATA[h Z3 / nm]]> 1000.86 1274.76 1239.67 1188.96 <![CDATA[h Z4 / nm]]> 778.44 911.08 1017.64 1027.5 <![CDATA[h Z5 / nm]]> 697.02 659.88 884.01 654.24 <![CDATA[h Z6 / nm]]> 554.05 509.9 493.4 608.11 <![CDATA[h Y1 / nm]]> 1932.99 2452.95 2307.09 2040.5 <![CDATA[h Y2 / nm]]> 1522.23 1939.55 1885.06 1807.76 <![CDATA[h Y3 / nm]]> 1183.96 1386.2 1547.44 1562.26 <![CDATA[h Y4 / nm]]> 1060.12 1004 1344.24 994.74 <![CDATA[h Y5 / nm]]> 842.66 775.82 750.27 924.6 <![CDATA[h1 / nm]]> 41.44 36.26 39.16 46.62 <![CDATA[h2 / nm]]> 148.99 130.37 140.8 167.61 <![CDATA[h3 / nm]]> 141.3 123.64 133.53 158.97 <![CDATA[h4 / nm]]> 94.8 82.95 89.59 106.65 <![CDATA[h5 / nm]]> 195.04 170.66 184.31 219.41 <![CDATA[h6 / nm]]> 121.29 106.13 114.62 136.45 <![CDATA[h7 / nm]]> 66.64 58.31 62.97 74.97 <![CDATA[h8 / nm]]> 424.37 371.32 401.03 477.41 <![CDATA[h9 / nm]]> 34.63 30.3 32.73 38.96 <![CDATA[h 10 / nm]]> 943.63 825.68 891.73 1061.59

[0170] Table 4 The number of times and thickness of the surface shape correction of the Ge substrate in all examples

[0171] Example 1 Example 2 Example 3 Example 4 Number of surface shape corrections 3 2 1 3 <![CDATA[h Ge-1 > 200 380 1100 450 <![CDATA[h Ge-2 > 650 630 / 320 <![CDATA[h Ge-3 > 150 / / 350

[0172] Table 5 The test results of all examples

[0173]

[0174]

[0175] Note: For the reflectivity values in Table 5, the upper position in the cell is the average reflectivity in the range of 0.5 - 0.8 μm, and the lower position is the average reflectivity in the range of 0.9 - 1.7 μm; for the transmittance values in Table 5, the upper position is the average transmittance in the range of 3 - 5 μm, and the lower position is the average transmittance in the range of 8 - 12 μm; λ is the test wavelength of the Zygo interferometer (λ = 632.8 nm).

[0176] As can be seen from Table 5, Example 1 is the preferred solution because for the beam splitter in Example 1, there are no phenomena such as wrinkling, cracking, or peeling on the film layer surface. Generally speaking, the reflectivity of the beam splitting film in the visible light and short-wave infrared regions, and the transmittance of the beam splitting film and the antireflection film in the mid- and long-wave infrared regions are the highest. Moreover, the surface form accuracy error E of the substrate before and after coating is 0.001λ, which is the lowest among the four examples, making this beam splitter have the best effect.

[0177] It should be noted that in the full text all represent angstroms (10 -10 m). The reference basis for step 11a in the preparation method of the beam splitter of the present invention is "GB / T 26332.4 - 2015 / ISO 9211 - 4:2012 Optics and Photonics - Optical Thin Films - Part 4: Specified Test Methods", the reference basis for step 11b is "GB / T 26332.4 - 2015 / ISO 9211 - 4:2012 Optics and Photonics - Optical Thin Films - Part 4: Specified Test Methods", and the reference basis for step 11c is "GB / T 26332.3 - 2015 / ISO 9211 - 3:2008 Optics and Photonics - Optical Thin Films - Part 3: Environmental Adaptability". RMS refers to Root Mean Square (root mean square value).

Claims

1. A spectroscope, characterized in that: The invention comprises a Ge substrate (1), a spectral film (2) plated on the front surface (11) of the Ge substrate (1), and an anti-reflection film (3) plated on the rear surface (12) of the Ge substrate (1); the spectral film (2) comprises six film stacks from near to far from the front surface of the Ge substrate (1), and the i-th film stack comprises T i The i-th membrane set, i = 1 to 6, T i =8~10, i and T i All are integers; Each of the first film sets includes two Ge layers with an optical thickness of λ1 / 8, and a ZnS layer with an optical thickness of λ1 / 4 arranged between the two Ge layers; each of the second film set, the third film set, the fourth film set, the fifth film set and the sixth film set includes two ZnS layers with an optical thickness of λ1 / 8, and a YbF3 layer with an optical thickness of λ1 / 4 arranged between the two ZnS layers; wherein λ1 is the central wavelength of the spectroscopic film (2); The anti-reflection film (3) includes ten layers of films with an optical thickness of λ2 / 4 from near to far from the rear surface of the Ge substrate (1), which are the first to tenth layers, respectively, ZnS layer, Ge layer, ZnS layer, Ge layer, ZnS layer, YbF3 layer, Ge layer, YbF3 layer, Ge layer, and YbF3 layer, wherein λ2 is the central wavelength of the anti-reflection film (3).

2. The spectroscope according to claim 1, characterized in that: The λ1=1700nm~1900nm; The λ2=700-900nm.

3. The spectroscope according to claim 2, characterized in that: The thickness h of the Ge substrate (1) is Ge0 =2mm; The sum of the thicknesses of all Ge layers in the first film stack is h G1 =850~1125nm; The total thickness of all ZnS layers in the first film stack is h Z1 =1580~2020nm; The total thickness of all ZnS layers in the second film stack is h Z2 =1268~1615nm; The total thickness of all ZnS layers in the third film stack is h Z3 =1000~1278; The total thickness of all ZnS layers in the fourth film stack h Z4 =777~1030nm; The total thickness of all ZnS layers in the fifth film stack h Z5 =654~700nm; The total thickness of all ZnS layers in the sixth film stack h Z6 =492~609nm; The sum of the thicknesses of all YbF3 layers in the second film stack is h Y1 =1930~2454nm; The sum of the thicknesses of all YbF3 layers in the third film stack is h Y2 =1520~1940nm; The total thickness of all YbF3 layers in the fourth film stack h Y3 =1182~1564nm; The total thickness of all YbF3 layers in the fifth film stack h Y4 =993~1345nm; The total thickness of all YbF3 layers in the sixth film stack h Y5 =750~925nm.

4. The spectroscope according to claim 3, characterized in that: The physical thickness of the first layer of the ten-layer film is h1=35-47nm; The physical thickness of the second layer of the ten-layer film is h2 = 129-168 nm; The physical thickness of the third layer of the ten-layer film is h3 = 122-160 nm; The physical thickness of the fourth layer of the ten-layer film is h4 = 81-107 nm; The physical thickness of the fifth layer of the ten-layer film is h5 = 169-220 nm; The physical thickness of the sixth layer of the ten-layer film is h6 = 105-138 nm; The physical thickness of the seventh layer of the ten-layer film is h7 = 57-75 nm; The physical thickness of the eighth layer of the ten-layer film is h8=370-480nm; The physical thickness of the ninth layer of the ten-layer film is h9=30-39 nm; The physical thickness h of the tenth layer in the ten-layer film 10 =823~1063nm.

5. The spectroscope according to any one of claims 1 to 4, characterized in that: T1=9, T2=8, T3=8, T4=8, T5=9, T6=9.

6. A method for preparing a spectroscope according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: prepare a Ge substrate (1), measure and obtain the RMS1 value of the surface shape of the front surface (11) of the Ge substrate (1), and then design the film system of the beam splitting film (2) and the anti-reflection film (3) according to actual needs and obtain design data, wherein the design data includes the total thickness h of all Ge layers in the first film stack of the beam splitting film (2). G1 , the total thickness of all ZnS layers in the first to sixth film stacks h Zi , the sum of the thicknesses of all YbF3 layers in the second to sixth film stacks h Yj , the physical thickness of the ten layers in the antireflection film (3) h k , as well as the baking temperature, deposition rate, anode voltage and cathode current parameters of the ion source during the preparation process of the spectroscopic film (2) and the anti-reflection film (3); Step 2, wiping and cleaning the front surface of the Ge substrate (1), then placing the Ge substrate (1) with the front surface facing downward into a coating tool, and clamping the coating tool onto a workpiece tray in the coating chamber; Step 3, evacuate the interior of the coating chamber; input the design data obtained in step 1 into the coating program of the spectroscopic film (2), and then start coating. The workpiece disk starts to rotate, and the film thickness controller controls the thickness of each layer of film. The rotation speed of the workpiece disk is r1 = 10-20 r / min, and the baking temperature is T 01 =100~120℃; Step 4: After the preparation of the spectroscopic film (2), the surface appearance of the film layer on the front surface of the Ge substrate (1) with the spectroscopic film (2) is inspected, and the visible-short-wave infrared reflectivity and the medium- and long-wave infrared transmittance of the spectroscopic film (2) are tested; if the test is qualified, the surface RMS2 value of the Ge substrate (1) is measured from the front surface direction, and step 5 is executed; if the appearance film layer is cracked or peeled off, or at least one of the reflectivity and transmittance is unqualified, the Ge substrate (1) with the spectroscopic film (2) is discarded, and the process returns to step 1, and at least one parameter in the design data is optimized; Step 5, wipe and clean the rear surface of the Ge substrate (1), then place the Ge substrate (1) with the rear surface facing downward into a coating tool, and clamp the coating tool onto a workpiece tray in the coating chamber; Step 6, evacuating the interior of the coating chamber; Step 7, using the deposition rate, the anode voltage and cathode current parameters of the ion source obtained in step 1, and the RMS2 value obtained in step 4 to perform surface correction on the Ge substrate (1) with the spectroscopic film (2), and obtain the surface correction data RMS5 value; Step 8. Perform step 5 again; Step 9, evacuate the interior of the coating chamber; use the RMS5 value of the surface correction data obtained in step 7 to correct the design data obtained in step 1, input the corrected design data into the coating program of the anti-reflection film (3), and then start coating. The workpiece disk starts to rotate, and the film thickness controller controls the thickness of each layer of the film. The rotation speed of the workpiece disk is r2 = 10-20r / min, and the baking temperature is T 02 =100~120℃; Step 10: After the antireflection film (3) is prepared, a spectroscope is obtained, and the transmittance of the mid-wave and long-wave infrared of the spectroscope is tested; if the test is qualified, step 11 is executed; if the test is unqualified, the spectroscope is discarded, and the process returns to step 1, and at least one parameter in the design data is optimized; Step 11, conduct adhesion test, anti-friction test and wet heat test on the prepared spectroscope; if all three tests are qualified, the spectroscope is judged to be qualified and the preparation is completed; if at least one of the three tests is unqualified, the spectroscope is judged to be unqualified, the prepared spectroscope is discarded, and return to step 1 for re-preparation.

7. The method for preparing a spectroscope according to claim 6, characterized in that: Step 7 is as follows: Step 7.1, edit the film system program of the single-layer Ge film, the first evaporation temperature T 03 =90~110℃, the first deposition rate is The anode voltage and cathode current parameters of the ion source are 100V / 1A. The thickness of the first Ge monolayer is calculated using the RMS2 value. Ge-1 Then, a layer with a thickness of h is plated on the rear surface of the Ge substrate (1). Ge-1 Ge monolayer film, where h Ge-1 =120~1200nm; Step 7.2, thickness is h Ge-1 After the Ge single-layer film is deposited, the surface RMS3 value of the Ge substrate (1) is measured from the front surface direction; Step 7.3, execute steps 5 and 6 again, edit the film system program of the single-layer Ge film, and the second evaporation temperature T 04 =90~110℃, the second deposition rate The anode voltage and cathode current parameters of the ion source are 100V / 1A. The thickness of the second Ge monolayer is calculated using the RMS3 value. Ge-2 Then, a layer with a thickness of h is plated on the rear surface of the Ge substrate (1). Ge-2 Ge monolayer film, where h Ge-2 =0~660nm; Step 7.4, thickness is h Ge-2 After the Ge single-layer film is deposited, the surface RMS4 value of the Ge substrate (1) is measured from the front surface direction; Step 7.5: Execute steps 5 and 6 again to edit the film system program of the single-layer Ge film. The third evaporation temperature T 05 =90~110℃, the third deposition rate The anode voltage and cathode current parameters of the ion source are 100V / 1A. The thickness of the third Ge monolayer is calculated using the RMS4 value. Ge-3 Then, a layer with a thickness of h is plated on the rear surface of the Ge substrate (1). Ge-3 Ge monolayer film, where h Ge-3 =0~360nm; Step 7.6, thickness is h Ge-3 After the Ge single-layer film is deposited, the RMS5 value of the surface shape of the Ge substrate (1) is measured from the front surface direction.

8. The method for preparing a spectroscope according to claim 7, characterized in that: Step 11 is as follows: Step 11a: Adhesion test of the beam splitter Use adhesive strength greater than 3N·cm -2 The adhesive tape is tightly attached to the front surface of the Ge substrate (1) in the beam splitter, and then pulled up vertically along the surface of the beam splitter film (2) at a pulling speed of 25 mm / s, and the surface of the beam splitter film (2) is checked under reflected light to see if there are any signs of peeling off; if there are no signs of peeling off and step 11c has not been performed, then step 11b is performed; if there are no signs of peeling off and step 11c has been performed, then the beam splitter adhesion test is determined to be qualified and the preparation is completed; if there are signs of peeling off, then the beam splitter is determined to be unqualified, the beam splitter prepared this time is discarded, and then the preparation is repeated in step 1; Step 11b: Conduct anti-friction test on the spectroscope Use absorbent cotton gauze to rub the surface of the splitter film (2) back and forth 25 times, and inspect the physical damage marks on the surface of the splitter film (2) under reflected light; If there is no physical damage, the spectroscope anti-friction test is determined to be qualified, and then step 11c is performed; If there are physical damage marks, the spectroscope is judged to be unqualified, the spectroscope prepared this time is discarded, and then return to step 1 to prepare it again; Step 11c: Perform a wet heat test on the spectroscope The spectroscope is exposed to an atmosphere with a relative humidity of 90% and a temperature of 55°C ± 2°C for 16 hours, with the front surface of the Ge substrate (1) facing upwards, and then the reflectivity and transmittance of the spectroscope are tested using a spectrophotometer; if both the reflectivity and the transmittance meet the actual requirements, the spectroscope is judged to have passed the wet heat test, and then the process returns to step 11a; if at least one of the reflectivity and the transmittance is unqualified, the spectroscope is judged to have failed, the spectroscope prepared this time is discarded, and then the process returns to step 1 for re-preparation.

9. The method for preparing a spectroscope according to claim 8, characterized in that: In steps 1, 4, 7 and 10, the device used to measure the surface profile of the Ge substrate (1) is a Zygo interferometer; In steps 2, 3, 5, 6, 8, and 9, the coating chambers are all ZZS1100 infrared vacuum coating chambers; In step 4, the visible-short-wave infrared reflectivity and medium- and long-wave infrared transmittance of the spectroscopic film (2) are tested, and in step 10, the medium- and long-wave infrared transmittance of the spectroscope is tested using a spectrophotometer. In step 2 and step 5, the tools used to wipe and clean the front surface and the back surface of the Ge substrate (1) are both absorbent cotton dipped in a mixed solution of anhydrous ethanol and ether, wherein the volume ratio of anhydrous ethanol to ether is 3:1; Step 2 also includes: using a strong light to check whether there is dust on the front surface of the Ge substrate (1) before cleaning, and if there is dust, using an ear cleaning ball to clean it; Step 5 also includes: using a strong light to check whether there is dust on the surface of the Ge substrate (1) after cleaning, and if there is dust, using an ear cleaning ball to clean it.

10. The method for preparing a spectroscope according to claim 9, characterized in that: In step 3, r1 = 15 r / min, T 01 =100℃; In step 9, r2 = 15 r / min, T 02 =100℃; In step 7.1, the T 03 =100℃, h Ge-1 =200nm; In step 7.3, the T 04 =100℃, h Ge-2 =650nm; In step 7.5, the T 05 =100℃, h Ge-3 =150nm.

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