A chalcogenide glass optical element and a preparation method thereof

Abstract

The present invention relates to a chalcogenide glass optical element. By forming symmetric antireflection film layers on both sides of the substrate, the stress of the antireflection film layers is kept substantially consistent, improving the surface shape quality of the substrate. In addition, in the present invention, ZnSe material is used as the transition layer. Since the composition of ZnSe is relatively close to that of the chalcogenide glass substrate and their microstructures are similar, the bonding force between ZnSe and the chalcogenide glass is good, which can significantly improve the bonding strength between the substrate and the antireflection film layer. In addition, the stress states of ZnS, ZnSe and the YbF3 film are opposite and cancel each other out, making the overall stress state of the antireflection film layer close to zero, and the film layer is more firm, thus solving the problem of film peeling. The average transmittance of the chalcogenide glass optical element of the present invention exceeds 95% in the wavelength ranges of 1.06 μm and 8 - 12 μm. The present invention also relates to a preparation method of the chalcogenide glass optical element. Through the optimization of process parameters such as film system structure design, transition layer selection and baking temperature, the purpose of controlling the change of the lens surface shape is achieved, and the firmness and transmittance of the film layer are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical thin films, and particularly relates to a chalcogenide glass optical element and a preparation method thereof. Background Art

[0002] In recent years, the development of infrared optical elements has been very rapid, and the preparation processes of traditional infrared materials such as Ge, ZnS, ZnSe, etc. have been very mature. However, the production processes of the above materials are relatively complex and the costs are very high. In view of this, people have begun to seek other alternative materials to reduce costs.

[0003] Chalcogenide glass is a multi-spectral infrared glass, which has the following main advantages: 1) It has a relatively high glass transition temperature, good mechanical properties, and a wide transmission range, covering the 1.064μm laser band and three important atmospheric windows of 1-3μm, 3-5μm, and 8-12μm; 2) Preparation and processing are easier than single crystal growth, and are not limited by size, and can even be directly molded; 3) In the design of infrared optical systems, chalcogenide glass is very suitable for use as a positive lens, has excellent compatibility with other infrared optical materials, can reduce the number of components, and improve the imaging performance of the optical system. Therefore, chalcogenide glass is regarded as an important candidate material to replace traditional infrared materials in thermal imaging systems. However, existing chalcogenide glass optical elements have problems such as out-of-tolerance surface shape and film peeling, which make the optical elements unable to meet the actual use requirements and even fail during use.

[0004] Therefore, it is necessary to develop a chalcogenide glass optical element and a preparation method thereof to solve problems such as poor surface shape and film peeling. Summary of the Invention

[0005] In order to overcome the disadvantages of the prior art, the present invention provides a chalcogenide glass optical element. By forming symmetric antireflection film layers on both sides of the substrate, the stress of the antireflection film layers is kept basically consistent, improving the surface shape quality of the substrate. In addition, the present invention uses a ZnSe material as a transition layer. Since the composition of ZnSe is relatively close to that of the chalcogenide glass substrate and the microstructures are similar, the bonding force between ZnSe and the chalcogenide glass is good, which can significantly improve the bonding strength between the substrate and the antireflection film layer. In addition, the stress states of ZnS, ZnSe, and the YbF3 film are opposite and cancel each other out, making the overall stress state of the antireflection film layer close to zero, and the film layer is more firm, thus solving the problem of film peeling.

[0006] In order to achieve the above object, the present invention provides the following technical solutions.

[0007] A chalcogenide glass optical element, comprising:

[0008] A substrate, the substrate being a chalcogenide glass; and

[0009] Two antireflection films are respectively disposed on the upper surface and the lower surface of the substrate. Each of the two antireflection films includes: a first layer film, a second layer film, a third layer film, a fourth layer film, a fifth layer film, a sixth layer film, a seventh layer film, and an eighth layer film sequentially disposed from the surface of the substrate. Among them, the first layer film is a ZnSe film, the second layer film, the fourth layer film, the sixth layer film, and the eighth layer film are all ZnS films, and the third layer film, the fifth layer film, and the seventh layer film are all YbF3 films.

[0010] In some embodiments, the film system structures on the upper and lower surfaces of the substrate can both be: Sub / x1H1 / x2H2 / x3L / x4H2 / x5L / x6H2 / x7L / x8H2 / Air, where Sub represents the substrate, Air represents air, H1 represents the ZnSe film with a 1 / 4 wavelength optical thickness, H2 represents the ZnS film with a 1 / 4 wavelength optical thickness, L represents the YbF3 film with a 1 / 4 wavelength optical thickness, and x1 to x9 respectively represent the optical thickness coefficients of each layer of film, and their values can be: x1 = 0.521, x2 = 0.703, x3 = 0.613, x4 = 0.055, x5 = 0.018, x6 = 0.093, x7 = 0.085, x8 = 0.009. By optimizing the thickness of each layer of film, the surface shape change can be further controlled and the firmness of the film layer can be improved.

[0011] The present invention also provides a method for preparing the chalcogenide glass optical element, including the following steps:

[0012] Put the substrate into a closed film-making environment and evacuate the film-making environment; and

[0013] Use the electron beam evaporation method to sequentially deposit the first to eighth layer films on one surface of the substrate; after the deposition is completed, use the same process to sequentially deposit the first to eighth layer films on the other surface of the substrate to obtain the chalcogenide glass optical element.

[0014] In some embodiments, before putting the substrate into a closed film-making environment, the substrate is cleaned. The cleaning may include: soaking and cleaning the surface of the substrate with anhydrous ethanol, cleaning it with an ultrasonic cleaner, and then wiping it with a mixture of alcohol and ether.

[0015] In some specific embodiments, the cleaning includes: first, soaking the substrate in alcohol for 10 - 20 minutes and gently wiping the surface of the substrate with long filament cotton; then, placing the substrate in an ultrasonic cleaning machine, ultrasonically cleaning it with deionized water for 10 minutes first, and then ultrasonically cleaning it with alcohol for 10 minutes; after ultrasonic cleaning, rinsing with alcohol, and then wiping the substrate 3 to 5 times with long filament cotton dipped in a mixed solution of alcohol and ether mixed in a certain ratio. After cleaning, the surface of the substrate can be inspected with a strong flashlight. If there are no stains, dust, or scratches on the surface, it can be placed in the enclosed film-forming environment for use.

[0016] In some embodiments, the film-forming environment is the vacuum chamber of a coating machine.

[0017] In some specific embodiments, the preparation method further includes: cleaning the dust in the vacuum chamber; respectively loading the ZnSe, ZnS, and YbF3 film materials into the oxygen-free copper crucibles in the vacuum chamber and placing them on the crucible chassis; loading the cleaned substrate into a coating collar, and then placing the substrate and the coating collar together on the planetary workpiece holder in the vacuum chamber; loading a new quartz crystal wafer.

[0018] In some specific embodiments, after loading the quartz crystal wafer, the vacuum system can be turned on. When the vacuum degree reaches below 8×10 -2 Pa, rotate the workpiece holder. The rotation speed can be set to 20 - 30 revolutions per minute.

[0019] In some embodiments, after placing the substrate in the enclosed film-forming environment and before coating, the substrate can be baked to increase the temperature of the substrate. In some specific embodiments, the baking can be performed after rotating the workpiece holder. In some specific embodiments, the baking temperature is 100°C - 150°C, and the baking time is 3 - 4 hours. The baking time can be counted from the start of heating. By baking the substrate and optimizing the baking temperature and time, the surface shape change can be further controlled and the film layer firmness can be improved. By baking the substrate at an appropriate temperature, the particles deposited on the surface of the substrate will obtain a certain ability to migrate on the surface of the substrate, ensuring a relatively uniform film formation and good smoothness; in addition, baking at an appropriate temperature can release some of the stress of the substrate and ensure the firmness of the coating.

[0020] In some embodiments, after baking, an ion source can be used to pre-bombard the substrate to remove the contaminants on the surface of the substrate. Through pre-bombardment, the cleanliness of the surface of the substrate can be improved, which helps to improve the film layer firmness.

[0021] In some embodiments, during the pre-bombardment, the ion source used can be a Kaufman ion source, the screen voltage of the ion source can be 340 - 360V, the ion beam current can be 55 - 65mA, and the bombardment time can be 5 - 10 min. By optimizing the ion source parameters and the bombardment time, the cleanliness of the substrate surface can be further improved.

[0022] In some embodiments, the deposition of the first to eighth layers of films all includes: depositing under a vacuum of 4×10 -3 Pa or less by electron beam evaporation, and the deposition rate can be 0.3 - 0.5 nm / s. The ion beam assisted evaporation coating process has the advantage of mature technology, and the film layer deposition rate and film layer thickness can be precisely controlled by a quartz crystal controller.

[0023] In some embodiments, baking is performed during the coating process, the baking temperature can be 90°C - 150°C, and at the same time, the ion source is turned on for bombardment.

[0024] In some embodiments, after the coating is completed, the baking switch is turned off, and the obtained chalcogenide glass optical element is cooled with the furnace; when the temperature of the vacuum chamber is not higher than 60°C, the vacuum chamber is opened, and the chalcogenide glass optical element is taken out.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention provides a chalcogenide glass optical element. By forming symmetric antireflection film layers on both sides of the substrate, the stress of the antireflection film layers is kept basically consistent, improving the surface shape quality of the substrate. In addition, in the present invention, ZnSe material is used as the transition layer. Since the composition of ZnSe is relatively close to that of the chalcogenide glass substrate and the microstructures are similar, the bonding force between ZnSe and the chalcogenide glass is good, which can significantly improve the bonding strength between the substrate and the antireflection film layer. In addition, the stress states of ZnS, ZnSe, and the YbF3 film are opposite and cancel each other out, making the overall stress state of the antireflection film layer close to zero, and the film layer is more firm, thus solving the problem of film peeling.

[0027] After the present invention deposits antireflection films on both sides of the chalcogenide glass substrate, the average transmittance in the wavelength ranges of 1.06 μm and 8 - 12 μm both exceeds 95%.

[0028] 2. The present invention achieves the purpose of controlling the change of the lens surface shape by optimizing process parameters such as film system structure design, transition layer selection, and baking temperature, improving the firmness and transmittance of the film layer, thereby ensuring the qualification rate and repeatability of the chalcogenide glass lens products. Description of the Drawings

[0029] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Also, throughout the drawings, the same reference symbols are used to represent the same components. In the drawings:

[0030] Figure 1 A schematic structural diagram of the chalcogenide glass optical element of the present invention is shown.

[0031] Figure 2 A transmittance curve graph of the chalcogenide glass substrate is shown.

[0032] Figure 3 A transmittance curve graph of the chalcogenide glass optical element of Example 1 of the present invention is shown.

[0033] Description of reference symbols:

[0034] 100 is the substrate, 200 is the antireflection film, 201 is the first layer film, 202 is the second layer film, 203 is the third layer film, 204 is the fourth layer film, 205 is the fifth layer film, 206 is the sixth layer film, 207 is the seventh layer film, and 208 is the eighth layer film. Detailed embodiments

[0035] To make the objectives, contents, and advantages of the present invention clearer, the following further describes the detailed embodiments of the present invention in conjunction with the drawings and examples. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein.

[0036] As Figure 1 shown, the chalcogenide glass optical element of the present invention includes:

[0037] A substrate 100, where the substrate 100 is a chalcogenide glass; and

[0038] Two antireflection films 200, which are respectively disposed on the upper surface and the lower surface of the substrate 100. The two antireflection films 200 both include: a first layer film 201, a second layer film 202, a third layer film 203, a fourth layer film 204, a fifth layer film 205, a sixth layer film 206, a seventh layer film 207, and an eighth layer film 208 that are sequentially disposed from the surface of the substrate 100. Among them, the first layer film 201 is a ZnSe film, and the second layer film 202, the fourth layer film 204, the sixth layer film 206, and the eighth layer film 208 are all ZnS films, and the third layer film 203, the fifth layer film 205, and the seventh layer film 207 are all YbF3 films.

[0039] The present invention also provides a method for preparing the chalcogenide glass optical element, including the following steps:

[0040] Place the substrate in a closed film - forming environment and evacuate the film - forming environment; and

[0041] Adopt the electron - beam evaporation method to deposit the first to eighth layers of films successively on one surface of the substrate; after the deposition is completed, adopt the same process to deposit the first to eighth layers of films successively on the other surface of the substrate to obtain a chalcogenide glass optical element.

[0042] The present invention realizes the preparation of a dual - band composite antireflection film with wavelengths of 1.06μm and 8 - 12μm on a chalcogenide glass substrate through means such as transition layer selection, film system design, and process optimization. The antireflection film is deposited by a double - side coating method, and the film system structures on both sides are the same.

[0043] In some specific embodiments, the film design and preparation method include the following steps:

[0044] 1. Film system design optimization: The substrate material is selected as chalcogenide glass, the high - refractive - index coating materials are zinc sulfide (ZnS) and zinc selenide (ZnSe), and the low - refractive - index coating material is YbF3. The antireflection film is deposited by a double - side coating method, and the film system structures on both sides are both:

[0045] Sub / x1H1 / x2H2 / x3L / x4H2 / x5L / x6H2 / x7L / x8H2 / Air, where Sub represents the substrate, Air represents air, H1 represents the ZnSe film with an optical thickness of 1 / 4 wavelength, H2 represents the ZnS film with an optical thickness of 1 / 4 wavelength, L represents the YbF3 film with an optical thickness of 1 / 4 wavelength, and x1~x9 respectively represent the optical thickness coefficients of each layer of film;

[0046] 2. Cleaning of the chalcogenide glass substrate: Immerse and clean the surface of the chalcogenide glass substrate to be coated with anhydrous ethanol, and clean it with an ultrasonic cleaner, and then wipe it with a mixture of alcohol and ether;

[0047] 3. Loading into the furnace: Load the chalcogenide glass substrate into the workpiece holder, install the crystal oscillator, and add appropriate amounts of ZnS, ZnSe, and YbF3 film materials;

[0048] 4. Baking of the substrate: Evacuate the equipment; before coating, bake and heat the chalcogenide glass substrate to increase the temperature of the chalcogenide glass substrate. The baking temperature is 100℃~150℃, and the baking time is 3~4 hours;

[0049] 5. Pre - bombardment of the chalcogenide glass substrate: After the baking is completed and before starting the coating, pre - bombard the coating substrate with a Kaufman ion source for 5~10 min;

[0050] 6. Anti-reflection coating deposition: According to the film system structure and film layer deposition process parameters, film layers are deposited on both the front and back sides of the chalcogenide glass substrate in sequence. The evaporation sequence of each layer of film material is ZnSe / ZnS / YbF3 / ZnS / YbF3 / ZnS / YbF3 / ZnS. The deposition process of each film layer is as follows:

[0051] Deposition of ZnSe film layer: The vacuum is pumped down to below 4×10 -3 Pa, and then electron beam evaporation is used for deposition. The deposition rate and thickness of the film layer are controlled by a quartz crystal oscillator thickness gauge;

[0052] Deposition of ZnS film layer: The vacuum is pumped down to below 4×10 -3 Pa, and then electron beam evaporation is used for deposition. The deposition rate of the film layer is 0.4 nm / s, and the deposition rate and thickness of the film layer are controlled by a quartz crystal oscillator thickness gauge;

[0053] Deposition of YbF3 film layer: The vacuum is pumped down to better than 4×10 -3 Pa, and then electron beam evaporation is used for deposition. The deposition rate of the film layer is 0.4 nm / s, and the deposition rate and thickness of the film layer are controlled by a quartz crystal oscillator thickness gauge.

[0054] Next, the technical solution of the present invention will be further explained in detail in the form of specific embodiments.

[0055] Example 1 Preparation method X1 of chalcogenide glass optical element

[0056] This method includes the following steps:

[0057] S1. Select chalcogenide glass As40Se60 (grade GG6) as the substrate, and the film system is designed as: Sub / 0.521H1 / 0.703H2 / 0.613L / 0.055H2 / 0.018L / 0.093H2 / 0.085L / 0.009H2 / Air, where H1 represents ZnSe with a 1 / 4 wavelength optical thickness, H2 represents ZnS with a 1 / 4 wavelength optical thickness, L represents YbF3 with a 1 / 4 wavelength optical thickness, Sub is the substrate, and Air is air.

[0058] S2. First, immerse the chalcogenide glass substrate in analytical pure alcohol for 10 min, and gently wipe the surface of the chalcogenide glass substrate with long filament cotton. Then, place the chalcogenide glass substrate in an ultrasonic cleaner, ultrasonically clean it with deionized water for 10 min first, and then ultrasonically clean it with alcohol for 10 min; after ultrasonic cleaning, rinse it clean with alcohol, and then wipe the substrate 3 to 5 times with long filament cotton dipped in a mixture of alcohol and ether mixed in a ratio of 3:1. Check the surface of the substrate with a strong light flashlight. After checking that there are no stains, dust, or scratches, it can be used.

[0059] S3. Clean the dust in the vacuum chamber, separately load the ZnSe, ZnS, and YbF3 film materials into oxygen-free copper crucibles, and place them on the crucible chassis; load the cleaned chalcogenide glass substrate into the coating collar, and then place the substrate and the coating collar together on the planetary workpiece holder in the vacuum chamber; load a new quartz crystal slice.

[0060] S4. Turn on the vacuum system. When the vacuum degree reaches 8×10 -2 Pa, turn on the rotation of the workpiece holder, and set the rotation speed to 20 revolutions per minute; turn on the baking switch of the vacuum chamber, heat the temperature of the chalcogenide glass substrate to 120 °C, and bake for 4 hours starting from the start of heating.

[0061] S5. Before the formal coating starts, turn on the ion source to pre-bombard the chalcogenide glass substrate for 10 min, set the ion source screen voltage to 350 V, and adjust the ion beam current to 60 mA.

[0062] S6. Evaporate the ZnSe film by electron beam evaporation method, and the deposition rate of the film layer is 0.4 nm / s; deposit the ZnS film by electron beam evaporation method, and the deposition rate of the film layer is 0.4 nm / s; deposit the YbF3 film by electron beam evaporation method, and the deposition rate of the film layer is 0.4 nm / s. Control the film layer deposition rate and film layer thickness through a quartz crystal controller. Bake during the coating process, the temperature is 120 °C, and at the same time turn on the ion source for bombardment.

[0063] After the coating is completed, turn off the baking switch, and the coated film cools down with the furnace; when the temperature of the vacuum chamber is not higher than 60 °C, open the vacuum chamber and take out the coated film to obtain the chalcogenide glass optical element.

[0064] Perform performance tests on the prepared dual-band chalcogenide glass optical element, and the test results are as follows.

[0065] 1. The transmittance of the chalcogenide glass optical element at 1.06 μm is 96.9%, and the average transmittance in the 8 - 12 μm wavelength range is 96.4%, as Figure 3 shown. The transmittance of the chalcogenide glass optical element of the present invention at 1.06 μm and in the 8 - 12 μm wavelength range is significantly higher than that of the chalcogenide glass substrate (as Figure 2 shown).

[0066] 2. Resistance to harsh environment performance: The chalcogenide glass optical element is tested as follows. The test results show that there are no obvious cracking, film peeling and other phenomena in the film layer, and the optical performance of the film layer remains unchanged.

[0067] ① High and low temperature test, keep at -50 °C and 65 °C for 2 h each, where the humidity is 95% at 65 °C, and cycle 24 periods.

[0068] ② Water solubility test, soak in pure water for 24 hours.

[0069] ③ Salt solubility test: Immerse in 4.5% brine for 24 hours.

[0070] ④ Adhesion test: Stick 3M Scotch tape on the surface of the film layer and then pull it down vertically with force.

[0071] Example 2 Preparation method of chalcogenide glass optical element X2

[0072] This method includes the following steps:

[0073] S1. Select chalcogenide glass (Ge22As20Se58) (grade GG4) as the substrate, and the film system is designed as: Sub / 0.521H1 / 0.703H2 / 0.613L / 0.055H2 / 0.018L / 0.093H2 / 0.085L / 0.009H2 / Air, where H1 represents ZnSe with a 1 / 4 wavelength optical thickness, H2 represents ZnS with a 1 / 4 wavelength optical thickness, L represents YbF3 with a 1 / 4 wavelength optical thickness, Sub is the substrate, and Air is air.

[0074] S2. First, immerse the chalcogenide glass substrate in analytical pure alcohol for 20 min and gently wipe the surface of the chalcogenide glass substrate with long filament cotton. Then, put the chalcogenide glass substrate into an ultrasonic cleaning machine, ultrasonically clean it with deionized water for 10 min first, and then ultrasonically clean it with alcohol for 10 min; after ultrasonic cleaning, rinse it with alcohol, and then wipe the substrate 3 to 5 times with long filament cotton dipped in a mixture of alcohol and ether mixed in a ratio of 3:1. Check the surface of the substrate with a strong light flashlight. It can be used after there are no stains, dust, or scratches.

[0075] S3. Clean the dust in the vacuum chamber, load ZnSe, ZnS, and YbF3 film materials into oxygen-free copper crucibles respectively, and put them into the crucible chassis; load the cleaned chalcogenide glass substrate into the coating collar, and then put the chalcogenide glass substrate and the coating collar together on the planetary workpiece holder in the vacuum chamber; load a new quartz crystal oscillator.

[0076] S4. Turn on the vacuum system. When the vacuum degree reaches 8×10 -2 Pa, turn on the rotation of the workpiece holder, and set the rotation speed to 20 revolutions per minute; turn on the baking switch of the vacuum chamber, heat the temperature of the chalcogenide glass substrate to 120 °C, and bake for 4 hours starting from the start of heating.

[0077] S5. Before the formal coating starts, turn on the ion source to pre-bombard the chalcogenide glass substrate for 10 min, set the ion source screen voltage to 350 V, and adjust the ion beam current to 60 mA.

[0078] S6. The ZnSe film is deposited by electron beam evaporation method with a deposition rate of 0.4 nm / s; the ZnS film is deposited by electron beam evaporation method with a deposition rate of 0.4 nm / s; the YbF3 film is deposited by electron beam evaporation method with a deposition rate of 0.4 nm / s. The deposition rate and thickness of the film layer are controlled by a quartz crystal controller. During the film coating process, baking is carried out at a temperature of 120 °C, and at the same time, the ion source is turned on for bombardment.

[0079] After the film coating is completed, turn off the baking switch, and the coated film cools down with the furnace; when the temperature of the vacuum chamber is not higher than 60 °C, open the vacuum chamber and take out the coated film to obtain the chalcogenide glass optical element.

[0080] Perform performance tests on the fabricated dual-band chalcogenide glass optical element, and the test results are as follows.

[0081] 1. The laser transmittance of the chalcogenide glass optical element at 1.06 μm is 95.1%, and the average transmittance in the 8 - 12 μm wavelength range is 95.4%.

[0082] 2. Performance in harsh environments: The chalcogenide glass optical element is tested as follows. The test results show that there are no obvious phenomena such as cracking or film peeling of the film layer, and the optical performance of the film layer remains unchanged.

[0083] ① High and low temperature test, maintaining at -50 °C and 65 °C for 2 hours each, with a humidity of 95% at 65 °C, and cycling for 24 periods.

[0084] ② Water solubility test, soaking in pure water for 24 hours.

[0085] ③ Salt solubility test, soaking in 4.5% saline for 24 hours.

[0086] ④ Adhesion test, using 3M Scotch tape to stick on the surface of the film layer, and then pulling it down vertically with force.

[0087] As described above, only the preferred specific embodiments of the present invention are shown, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A chalcogenide glass optical element, characterized in that, Comprising: A substrate, which is a chalcogenide glass; And Two antireflection films, which are respectively disposed on the upper surface and the lower surface of the substrate. The two antireflection films both include: a first layer film, a second layer film, a third layer film, a fourth layer film, a fifth layer film, a sixth layer film, a seventh layer film, and an eighth layer film sequentially disposed from the surface of the substrate. Among them, the first layer film is a ZnSe film, the second layer film, the fourth layer film, the sixth layer film, and the eighth layer film are all ZnS films, and the third layer film, the fifth layer film, and the seventh layer film are all YbF3 films; The film system structures on the upper and lower surfaces of the substrate are both: Sub / x1H1 / x2H2 / x3L / x4H2 / x5L / x6H2 / x7L / x8H2 / Air, Wherein, Sub represents the substrate, Air represents air, H1 represents the ZnSe film with an optical thickness of 1 / 4 wavelength, H2 represents the ZnS film with an optical thickness of 1 / 4 wavelength, L represents the YbF3 film with an optical thickness of 1 / 4 wavelength, x1 to x9 respectively represent the optical thickness coefficients of each layer of film, and their values are respectively: x1 = 0.521, x2 = 0.703, x3 = 0.613, x4 = 0.055, x5 = 0.018, x6 = 0.093, x7 = 0.085, x8 = 0.

009.

2. The method for preparing a chalcogenide glass optical element according to claim 1, characterized in that, Including the following steps: Put the substrate into a closed film-making environment and evacuate the film-making environment; And Use the electron beam evaporation method to sequentially deposit the first to eighth layer films on one surface of the substrate; after the deposition is completed, use the same process to sequentially deposit the first to eighth layer films on the other surface of the substrate to obtain a chalcogenide glass optical element.

3. The preparation method according to claim 2, wherein, After putting the substrate into a closed film-making environment and before coating, bake the substrate to increase the temperature of the substrate.

4. The preparation method according to claim 3, wherein The baking temperature is 100°C to 150°C, and the baking time is 3 to 4 hours.

5. The preparation method according to claim 3 or 4, characterized in that After baking, use an ion source to pre-bombard the substrate to remove contaminants on the surface of the substrate.

6. The preparation method according to claim 5, characterized in that, The ion source is a Kaufman ion source, the ion source screen voltage is 340 - 360V, the ion beam current is 55 - 65mA, and the bombardment time is 5 to 10 minutes.

7. The preparation method according to claim 2 or 3, characterized in that The deposition of the first to eighth layers of films all includes: under a vacuum of 4×10 -3 Pa or less, the deposition is carried out by electron beam evaporation method, and the deposition rate is 0.3 - 0.5 nm / s.

8. The preparation method according to claim 2 or 3, characterized in that, During the coating process, bake at a temperature of 90°C to 150°C, and at the same time turn on the ion source for bombardment.

9. The preparation method according to claim 2 or 3, characterized in that, Before putting the substrate into a closed film-making environment, clean the substrate; the cleaning includes: soaking and cleaning the surface of the substrate with anhydrous ethanol, cleaning with an ultrasonic cleaner, and then wiping with a mixture of alcohol and ether.

Images