A multilayer chalcogenide glass with varying refractive index and its preparation method

Abstract

This invention provides a multilayer chalcogenide glass with a refractive index gradient, characterized in that the multilayer chalcogenide glass comprises a first surface matrix chalcogenide glass, an interlayer matrix chalcogenide glass, and a second surface matrix chalcogenide glass stacked sequentially; and the number of layers in the interlayer matrix chalcogenide glass is greater than or equal to 0; the matrix chalcogenide glass comprises Ge 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 The refractive index of the multilayer chalcogenide glass decreases sequentially from the first surface matrix chalcogenide glass to the interlayer matrix chalcogenide glass and then to the second surface matrix chalcogenide glass. This invention also provides a method for preparing this multilayer chalcogenide glass. The multilayer chalcogenide glass prepared by this invention requires no binder and produces multilayer chalcogenide glass with good imaging quality and a high refractive index difference, possessing high commercial and promotional value.

Description

Technical Field

[0001] This invention relates to the field of chalcogenide glass preparation technology, and more specifically, to a multilayer chalcogenide glass with a refractive index gradient and its preparation method. Background Technology

[0002] Each infrared spectral band has its unique advantages. For example, mid-wave infrared (MWIR) is typically used for imaging hot objects, while long-wave infrared (LWIR) is better suited for imaging and identification at ambient temperatures. The rapid growth of infrared (IR) imaging, sensing, and detection systems deployed in various military and civilian applications over the past decade has been largely due to advancements in infrared materials and detection technologies. Chalcogenide glasses, because their materials are not locked into a specific stoichiometry, can have their properties altered by changing their composition to obtain the desired material, offering excellent cost-effectiveness and making them widely used in infrared imaging and detection.

[0003] Traditional infrared optical imaging systems typically use adhesives to eliminate chromatic aberration by combining multiple optical elements of varying thicknesses and with a single refractive index. However, with the increasing complexity of applications, especially in multi-spectral fusion scenarios, the adhesive approach is no longer suitable. First, there is a lack of suitable transparent infrared or multispectral adhesives; second, the use of adhesives not only leads to light intensity attenuation, affecting image quality, but also results in more complex, heavier, and larger lens optical designs, which contradicts the current demands for miniaturization, precision, and lightweight optical systems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a multilayer chalcogenide glass with a refractive index gradient to solve the problems of poor imaging quality and low refractive index difference of conventional multilayer chalcogenide glasses.

[0005] To address the aforementioned problems, this invention provides a multilayer chalcogenide glass with a varying refractive index. The multilayer chalcogenide glass comprises a first surface matrix chalcogenide glass, an interlayer matrix chalcogenide glass, and a second surface matrix chalcogenide glass, which are stacked sequentially. The number of layers in the interlayer matrix chalcogenide glass is greater than or equal to 0.

[0006] The matrix chalcogenide glass includes Ge 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te15 ;

[0007] The refractive index of the multilayer chalcogenide glass decreases sequentially from the first surface matrix chalcogenide glass to the interlayer matrix chalcogenide glass and then to the second surface matrix chalcogenide glass.

[0008] As a preferred embodiment, the sandwich matrix chalcogenide glass has three layers, which sequentially include Ge5As. 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 The stacking order of the layers of the multilayer chalcogenide glass with varying refractive index gradient is as follows: Ge 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 .

[0009] As a preferred embodiment, the thickness of the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass, and the second surface matrix chalcogenide glass are all less than or equal to 3 mm, and the diameter is less than or equal to 50 mm.

[0010] This invention provides a multilayer chalcogenide glass with a refractive index gradient. By utilizing the similar thermodynamics of a series of matrix chalcogenide glasses, glasses with different refractive indices are stacked sequentially and hot-pressed together to obtain the multilayer chalcogenide glass with a refractive index gradient of this invention. In the multilayer chalcogenide glass of this invention, no glue or resin is used between the glasses, and they are tightly bonded without gaps, thereby reducing the size, weight and complexity of the system.

[0011] Another technical problem to be solved by the present invention is to provide a method for preparing multilayer chalcogenide glass with the aforementioned refractive index gradient, so as to solve the problem that other methods in the prior art require the use of adhesives in the preparation process, which affects the structure and imaging quality of multilayer chalcogenide glass.

[0012] To address the above problems, the present invention also provides a method for preparing the multilayer chalcogenide glass with a refractive index gradient, comprising the following steps:

[0013] S1: The raw materials of the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass are weighed and then sequentially subjected to the steps of tube insertion, vacuuming, sealing, melt quenching and annealing to prepare the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass. The first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass are then cut and polished.

[0014] S2: The first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass obtained in step S1 are stacked in sequence and then bonded by hot pressing and cooled to obtain a multilayer chalcogenide glass with a changing refractive index.

[0015] As a preferred embodiment, in step S1, the purity of the raw materials for the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass, and the second surface matrix chalcogenide glass is all greater than 5N; the polishing condition is: polishing until the transmittance of the chalcogenide glass is higher than 55%.

[0016] As a preferred embodiment, in step S1, the vacuuming step requires preheating at a temperature of 100°C, and the vacuum level during vacuuming is below 10. -5 The melting temperature is mbar, and the time is greater than or equal to 3 hours; the melting heating rate is 5-10℃ / h, the holding temperature is 850-900℃, and the holding time is 10-15h; the quenching method is air cooling.

[0017] As a preferred embodiment, in step S2, during the hot-press bonding, a 0.1mm molybdenum sheet is provided on the outside of the first surface matrix chalcogenide glass and the second surface matrix chalcogenide glass. The molybdenum sheet is respectively disposed between the contact surface of the first surface matrix chalcogenide glass and the second surface matrix chalcogenide glass and the mold to prevent the mold from sticking to the glass.

[0018] As a preferred embodiment, in step S2, the heating rate of the hot-press bonding is 5–20°C / min, the holding temperature is 180–230°C, the pressure is 0–50 MPa, the time is 1–5 h, and the vacuum degree is <10. -2 Pa.

[0019] As a preferred embodiment, the cooling rate is 1-2°C / min, and the pressure drops to 0 when the temperature drops to 180-190°C.

[0020] This invention provides a method for preparing multilayer chalcogenide glasses with a refractive index gradient. It provides a series of matrix chalcogenide glasses with similar glass transition temperatures and coefficients of thermal expansion but different refractive indices. This method produces multilayer chalcogenide glasses with a refractive index gradient without the use of any glue or resin. By cutting and polishing the matrix chalcogenide glasses to a smooth finish, the infrared window transmittance reaches over 55%. The matrix chalcogenide glasses are stacked sequentially in a specially designed mold with decreasing refractive indices. At 25°C, the refractive index of the matrix chalcogenide glasses at a wavelength of 10 μm is 2.564–2.835, and the refractive index difference (Δn) can reach up to 0.271, achieving a large refractive index gradient. This invention utilizes the thermodynamic properties of glass to tightly bond multiple matrix chalcogenide glasses without gaps, thereby reducing the size, weight, and complexity of the system, and has excellent application prospects in infrared imaging and detection systems. Attached Figure Description

[0021] Figure 1 This is a graph showing the refractive index of the matrix chalcogenide glass in Example 3 of the present invention. Figure 1 In the middle, from bottom to top, they correspond to Ge. 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 The curve.

[0022] Figure 2 This is a transmission curve of the multilayer chalcogenide glass in Example 3 of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This invention provides a multilayer chalcogenide glass with a refractive index gradient, the multilayer chalcogenide glass comprising a first surface matrix chalcogenide glass, an interlayer matrix chalcogenide glass, and a second surface matrix chalcogenide glass stacked sequentially; and the number of layers of the interlayer matrix chalcogenide glass is greater than or equal to 0.

[0025] The matrix chalcogenide glass includes Ge 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 ;

[0026] The refractive index of the multilayer chalcogenide glass decreases sequentially from the first surface matrix chalcogenide glass to the interlayer matrix chalcogenide glass and then to the second surface matrix chalcogenide glass.

[0027] As a preferred embodiment, the sandwich matrix chalcogenide glass has three layers, which sequentially include Ge5As. 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 The stacking order of the layers of the multilayer chalcogenide glass with varying refractive index gradient is as follows: Ge 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 .

[0028] Preferably, the thickness of the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass, and the second surface matrix chalcogenide glass are all less than or equal to 3 mm, and the diameter is less than or equal to 50 mm.

[0029] The present invention also provides a method for preparing the multilayer chalcogenide glass with the aforementioned refractive index gradient, comprising the following steps:

[0030] S1: The raw materials of the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass are weighed and then sequentially subjected to the steps of tube insertion, vacuuming, sealing, melt quenching and annealing to prepare the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass. The first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass are then cut and polished.

[0031] S2: The first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass obtained in step S1 are stacked in sequence and then bonded by hot pressing and cooled to obtain a multilayer chalcogenide glass with a changing refractive index.

[0032] Preferably, in step S1, the purity of the raw materials for the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass, and the second surface matrix chalcogenide glass is greater than 5N; the polishing condition is: polishing until the transmittance of the chalcogenide glass is higher than 55%.

[0033] Preferably, in step S1, the vacuuming step requires preheating at a temperature of 100°C, and the vacuum level is below 10. -5 The melting temperature is mbar, and the time is greater than or equal to 3 hours; the melting heating rate is 5-10℃ / h, the holding temperature is 850-900℃, and the holding time is 10-15h; the quenching method is air cooling.

[0034] Preferably, in step S2, during the hot-press bonding, a 0.1 mm molybdenum sheet is disposed on the outside of the first surface matrix chalcogenide glass and the second surface matrix chalcogenide glass.

[0035] Preferably, in step S2, the heating rate of the hot-press bonding is 5–20°C / min, the holding temperature is 180–230°C, the pressure is 0–50 MPa, the time is 1–5 h, and the vacuum degree is <10. -2 Pa.

[0036] Preferably, the cooling rate is 1-2°C / min, and the pressure drops to 0 when the temperature drops to 180-190°C.

[0037] Step S1 of this invention provides a method for preparing matrix chalcogenide glass, which includes steps such as weighing raw materials, inserting them into a tube, vacuuming, sealing, melting and quenching, and annealing. The purity of the raw materials for matrix chalcogenide glass is 5N. Preheating is required during the vacuuming process, with a preheating temperature of 80–100°C; the vacuum level during vacuuming is below 10. -5mbar, the time should be no less than 2 to 3 hours; in the melting and quenching stage, the temperature rise rate from 30℃ to the melting and holding temperature is 5 to 10℃ / h, the melting and holding temperature is 850 to 900℃, and the holding time is 10 to 15 hours; air cooling quenching is used.

[0038] In step S2 of this invention, a method for preparing a series of matrix chalcogenides with similar glass transition temperatures and coefficients of thermal expansion but different refractive indices is provided. The matrix chalcogenides include Ge... 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 The matrix chalcogenide glass is cut and polished until smooth and free of scratches, with a thickness of 2-3 mm and a diameter of 50 mm. The matrix chalcogenide glass is then stacked in the mold in order of decreasing refractive index. A 0.1 mm thick molybdenum sheet is inserted between the first and second surface layers and the mold's contact surface to prevent the mold from sticking to the glass. The mold is then placed in a hot press, and a vacuum is created to a level below 10. -2 Pa; the heating rate from room temperature to the holding temperature of the hot-press bonding is 5-20℃ / min, the holding temperature of the hot-press bonding is 180-230℃, the pressure is 0-50MPa, and the time is 1-5h; during the cooling stage of the hot-press bonding, the cooling rate is 1-5℃ / min, and the pressure drops to 0 when the temperature drops to 180-190℃; it is made into a multilayer chalcogenide glass with a refractive index gradient without using any glue or resin.

[0039] To better describe the above technical solutions, a detailed explanation will be provided below in conjunction with the embodiments and accompanying drawings.

[0040] The following provides specific embodiments, incorporating concrete data and equipment, to elaborate on the above-described technical solutions of the present invention:

[0041] Example 1

[0042] This embodiment provides a method for preparing a two-layer chalcogenide glass with a varying refractive index. The glass composition and related properties are as follows:

[0043] Example 1 provides a solution when the interlayer base chalcogenide glass has zero layers, i.e., it only includes the first layer and the second layer of base chalcogenide glass:

[0044]

[0045]

[0046] S1: Preparation of Ge 10 As 25 Se 65 Ge5As 40 Se 55 The specific preparation methods for two types of matrix chalcogenide glasses are as follows: First, weigh 100g of elemental Ge, As, and Se with a purity of 5N according to the glass composition, and mix the raw materials in a quartz tube with an inner diameter of 50mm. Then, evacuate the tube for at least 2-3 hours to ensure that the vacuum level inside the quartz tube is below 10. -5 mbar; Preheating is required during the vacuuming process at a temperature of 80–100℃ to remove surface moisture; after vacuuming, the opening of the quartz tube is sealed with an oxyhydrogen flame. The quartz tube is then placed in a oscillating furnace for high-temperature melting and oscillation to ensure a complete reaction. The furnace temperature is increased from 30℃ to the melting holding temperature at a rate of 5–10℃ / min, and the melting holding temperature is 850℃ for 12 hours. After the holding period, the furnace is stopped from oscillating and cooled. The furnace is cooled to 450–430℃ within 1 hour, and the glass is then removed and air-cooled to quench the chalcogenide glass and allow it to detach from its walls. The quenched quartz tube is then placed in an annealing furnace for annealing to eliminate internal stress in the chalcogenide glass. Ge 10 As 25 Se 65 Annealing holding temperature 180℃, Ge5As 40 Se 55 The annealing temperature was 185℃, and the annealing time for both types of glass was 6 hours. Subsequently, cooling annealing was performed at a rate of -3℃ / min.

[0047] The prepared matrix chalcogenide glass is cut and polished on both sides to a thickness of 2-3 mm and a diameter of 50 mm, with both sides parallel. Its transmittance is then tested, and the transmittance must be higher than 55%.

[0048] S2: Polished Ge 10 As 25 Se 65 Ge5As 40 Se 55 The materials are placed into the mold sequentially, with 0.1mm molybdenum sheets inserted between the contact surfaces with the mold. The mold is then placed in a hot press and a vacuum is applied, with a vacuum level <10. -2Pa. When the temperature inside the mold is gradually increased to 210℃ at a rate of 5℃ / min, the pressure is gradually applied to 10 MPa and the holding time is 1.5h. After hot pressing and bonding, the temperature is reduced at a rate of -5℃ / min. When the temperature drops to 193℃, the pressure is released to 0, and the furnace temperature is reduced to room temperature at a rate of 1℃ / min. Then the glass is taken out.

[0049] Grind and polish both sides of the glass sheet until they are parallel to each other. Test the transmittance of the multilayer glass; the transmittance must be greater than 55%.

[0050] The two chalcogenide glasses prepared in this embodiment have a refractive index difference (Δn) of 0.083 at a wavelength of 10 μm.

[0051] Example 2

[0052] Example 2 provides a solution when the interlayer base layer is two layers of chalcogenide glass:

[0053] This embodiment provides a method for preparing a four-layer chalcogenide glass with a refractive index gradient. The glass composition and related properties are as follows:

[0054]

[0055] S1: In Ge5As 40 Se 55 Based on glass, tellurium is gradually incorporated. Tellurium has a high atomic mass and polarizability, which can significantly improve the linear refractive index of multi-component chalcogenide glasses. It can also broaden the refractive index range while having a relatively small impact on the glass transition temperature and coefficient of thermal expansion. Preparation of Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 The specific preparation method for tetra-matrix chalcogenide glass is as follows: First, weigh 100g of elemental Ge, As, Se, or Te with a purity of 5N according to the glass composition, and mix the raw materials in a quartz tube with an inner diameter of 50mm. Then, evacuate the tube for at least 2-3 hours to ensure the vacuum level inside the quartz tube is below 10. -5mbar; Preheating is required during the vacuuming process at a temperature of 80–100℃ to remove surface moisture; after vacuuming, the opening of the quartz tube is sealed with an oxyhydrogen flame. The quartz tube is then placed in a gyratory furnace for high-temperature melting and gyratory operation to ensure complete reaction. The furnace temperature is increased from 30℃ to the melting holding temperature at a rate of 5–10℃ / min, and the melting holding temperature is 850℃ for 12 hours. Finally, after the holding period, the furnace is stopped from gyrating and the temperature is reduced to the outlet temperature within 1 hour. Ge5As 40 Se 55 Ge5As 40 Se 50 The furnace temperature for Te5 is 450℃, and for Ge5As... 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 The furnace exit temperature is 430℃. After exiting the furnace, the quartz glass tube is air-cooled to quench the internal chalcogenide glass, causing it to detach from its inner walls. The quenched quartz tube is then placed in an annealing furnace for annealing to relieve internal stress in the chalcogenide glass. Ge5As 40 Se 55 Ge5As 40 Se 50 The annealing holding temperature for Te5 is 185℃, and for Ge5As... 40 Se 45 Te 10 Annealing holding temperature 180℃, Ge5As 40 Se 40 Te 15 The annealing temperature was 175℃, and the annealing time for the three types of glass was 6 hours. Subsequently, cooling annealing was carried out at a rate of -3℃ / min.

[0056] The prepared matrix chalcogenide glass is cut and polished on both sides to a thickness of 2-3 mm and a diameter of 50 mm, with both sides parallel. Its transmittance is then tested, and the transmittance must be higher than 55%.

[0057] S2: Polished Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 Place them sequentially into the mold, and in Ge5As 40 Se 55 With molds and Ge5As 40 Se40 Te 15 Insert 0.1mm molybdenum sheets between the contact surfaces of the mold and the mold. Then place the mold in a hot press and evacuate it to a vacuum level <10. -2 Pa. When the temperature inside the mold is gradually increased to 210℃ at a rate of 5℃ / min, the pressure is gradually applied to 10 MPa and the holding time is 1.7h. After hot pressing and bonding, the temperature is reduced at a rate of -5℃ / min. When the temperature drops to the glass transition temperature of 185℃, the pressure is released to 0, and the furnace temperature is reduced to room temperature at a rate of 1℃ / min. Then the glass is taken out.

[0058] Grind and polish both sides of the glass sheet until they are parallel to each other. Test the transmittance of the multilayer glass; the transmittance must be greater than 55%.

[0059] The four-layer chalcogenide glass prepared in this embodiment has a refractive index difference (Δn) of 0.188 at a wavelength of 10 μm.

[0060] Example 3

[0061] Example 3 provides a solution when the interlayer base layer is 3 layers of chalcogenide glass:

[0062] This embodiment provides a method for preparing a five-layer chalcogenide glass with a varying refractive index. Figure 1 The five matrix chalcogenide glass components and their related properties are as follows:

[0063]

[0064] S1: Preparation of Ge 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 The specific preparation methods for five types of matrix chalcogenide glasses are as follows: First, weigh 100g of elemental Ge, As, Se, or Te with a purity of 5N according to the glass composition, and mix the raw materials in a quartz tube with an inner diameter of 50mm. Then, evacuate the tube for at least 2-3 hours to ensure the vacuum level inside the quartz tube is below 10. -5mbar; Preheating is required during the vacuuming process at a temperature of 80–100℃ to remove surface moisture; after vacuuming, the opening of the quartz tube is sealed with an oxyhydrogen flame. The quartz tube is then placed in a gyratory furnace for high-temperature melting and gyratory operation to ensure complete reaction. The furnace temperature is increased from 30℃ to the melting holding temperature at a rate of 5–10℃ / min, and the melting holding temperature is 850℃ for 12 hours. Finally, after the holding period, the furnace is stopped from gyrating and the temperature is reduced to the outlet temperature within 1 hour. Ge5As 40 Se 55 Ge5As 40 Se 50 The furnace temperature for Te5 is 450℃, Ge 10 As 25 Se 65 Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 The furnace exit temperature is 430℃. After exiting the furnace, the quartz glass tube is air-cooled to quench the internal chalcogenide glass, causing it to detach from its inner walls. The quenched quartz tube is then placed in an annealing furnace for annealing to relieve internal stress in the chalcogenide glass. Ge5As 40 Se 55 Ge5As 40 Se 50 The annealing holding temperature for Te5 is 185℃, Ge 10 As 25 Se 65 Ge5As 40 Se 45 Te 10 Annealing holding temperature 180℃, Ge5As 40 Se 40 Te 15 The annealing temperature was 175℃, and the annealing time for the five types of glass was 6 hours. Subsequently, cooling annealing was carried out at a rate of -3℃ / min.

[0065] The prepared matrix chalcogenide glass is cut and polished on both sides to a smooth finish. Its transmittance is then tested, and the transmittance must be higher than 55%.

[0066] S2: Polished Ge 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10Ge5As 40 Se 40 Te 15 Place them one by one into the mold, and in Ge 10 As 25 Se 65 With molds and Ge5As 40 Se 40 Te 15 Insert 0.1mm molybdenum sheets between the contact surfaces of the mold and the mold. Then place the mold in a hot press and evacuate it to a vacuum level <10. -2 Pa. When the temperature inside the mold is gradually increased to 210℃ at a rate of 5℃ / min, the pressure is gradually applied to 10 MPa and the holding time is 2 hours. After hot pressing and bonding, the temperature is reduced at a rate of -1℃ / min. When the temperature drops to the glass transition temperature of 185℃, the pressure is released to 0, and the furnace temperature is reduced to room temperature at a rate of 1℃ / min. Then the glass is taken out.

[0067] Grind and polish both sides of the glass sheet until they are parallel to each other. Test the transmittance of the multilayer glass; the transmittance must be greater than 55%.

[0068] The five-layer chalcogenide glass prepared in this embodiment has a refractive index difference (Δn) of 0.271 at a wavelength of 10 μm.

[0069] Further testing through the above embodiments also proves that the multilayer chalcogenide glass prepared by the method of the present invention can be made into multilayer chalcogenide glass with refractive index gradient without the use of any glue or resin. Moreover, the multilayer chalcogenide glass has high performance at a specific wavelength, can eliminate chromatic aberration to achieve imaging, and the technical effect is optimal when three layers of chalcogenide glass are used as the interlayer base layer, realizing a large gradient change in refractive index.

[0070] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A method for preparing a multilayer chalcogenide glass with a refractive index gradient, characterized in that, Includes the following steps: S1: The raw materials of the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass are weighed and then sequentially subjected to the steps of tube insertion, vacuuming, sealing, melt quenching and annealing to prepare the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass. The first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass are then cut and polished. S2: The first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass and the second surface matrix chalcogenide glass obtained in step S1 are stacked in sequence and then bonded by hot pressing and cooled to obtain a multilayer chalcogenide glass with a changing refractive index. The multilayer chalcogenide glass comprises a first surface matrix chalcogenide glass, an interlayer matrix chalcogenide glass, and a second surface matrix chalcogenide glass, which are stacked sequentially. The matrix chalcogenide glass includes Ge 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15 ; The refractive index of the multilayer chalcogenide glass decreases sequentially from the first surface matrix chalcogenide glass to the interlayer matrix chalcogenide glass and then to the second surface matrix chalcogenide glass. In step S1, the vacuuming step requires preheating at a temperature of 100°C, and the vacuum level is below 10. -5 mbar, time greater than or equal to 3 hours; the melting heating rate is 5~10℃ / h, the holding temperature is 850~900℃, and the holding time is 10~15h; the quenching method is air cooling; The interlayer matrix chalcogenide glass has three layers, which sequentially include Ge5As. 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 The stacking order of the layers of the multilayer chalcogenide glass with varying refractive index gradient is as follows: Ge 10 As 25 Se 65 Ge5As 40 Se 55 Ge5As 40 Se 50 Te5, Ge5As 40 Se 45 Te 10 Ge5As 40 Se 40 Te 15； In step S2, the heating rate of the hot-press bonding is 5–20°C / min, the holding temperature is 180–230°C, the pressure is 0–50 MPa, the time is 1–5 h, and the vacuum degree is <10. -2 Pa; The cooling rate is 1~2℃ / min, and the pressure drops to 0 when the temperature drops to 180~190℃.

2. The method for preparing multilayer chalcogenide glass with refractive index gradient according to claim 1, characterized in that: The diameters of the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass, and the second surface matrix chalcogenide glass are all less than or equal to 50 mm.

3. The method for preparing multilayer chalcogenide glass with refractive index gradient according to claim 1, characterized in that: The thicknesses of the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass, and the second surface matrix chalcogenide glass are all less than or equal to 3 mm.

4. The method for preparing multilayer chalcogenide glass with refractive index gradient according to claim 1, characterized in that: In step S1, the purity of the raw materials for the first surface matrix chalcogenide glass, the interlayer matrix chalcogenide glass, and the second surface matrix chalcogenide glass is greater than 5N; the polishing condition is: polishing until the transmittance of the chalcogenide glass is higher than 55%.

5. The method for preparing multilayer chalcogenide glass with refractive index gradient according to claim 1, characterized in that: In step S2, during the hot-press bonding, a 0.1mm molybdenum sheet is disposed on the outside of the first surface matrix chalcogenide glass and the second surface matrix chalcogenide glass.

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