JP2023055193A - Immersion diffraction element and method of manufacturing the same - Google Patents

Abstract

To provide an immersion diffraction element which is easy to manufacture and offers improved design flexibility of a diffractive portion.SOLUTION: An immersion diffraction element 1 is provided, comprising a prism portion 2 and a diffractive portion 4. The prism portion 2 and the diffractive portion 4 are made of amorphous glass.SELECTED DRAWING: Figure 1

Description

The present invention relates to an immersion diffraction element and a method for manufacturing the immersion diffraction element.

In recent years, immersion diffraction elements have been attracting attention because they enable miniaturization of spectroscopes and improvement in wavelength resolution compared to general reflective elements. The immersion diffraction element has, for example, a structure in which a prism is provided with a diffraction section. A plurality of diffraction grooves are provided periodically in the diffraction section. In spectroscopy by the immersion diffraction element, light passes through the prism and is reflected and spectroscopy at the diffraction section. The split light is then emitted from the prism.

Assuming that the refractive index of the prism is n, the wavelength of the light becomes 1/n when the light passes through the prism. Therefore, the pitch of the diffraction grooves required for spectroscopy is 1/n. Therefore, even if the immersion diffraction element is miniaturized, a large number of diffraction grooves can be provided, and the wavelength resolution can be improved.

Patent Documents 1 and 2 below disclose a diffraction grating as an example of an immersion diffraction element. Patent Literature 1 discloses a diffraction grating in which a single-crystal Ge or single-crystal Si material is used and grating grooves are formed in the (111) plane of the crystal orientation. Further, Patent Document 2 discloses a diffraction grating in which grating grooves are provided in a crystal material of InP or InAs. The lattice grooves contain the (110) plane, which is the crystallographic orientation of the crystalline material.

JP-A-2003-75622 JP 2015-121605 A

However, when lattice grooves are formed in a crystal material as in Patent Documents 1 and 2, the lattice grooves are formed by processing the crystal material, such as cutting and etching. Therefore, there is a problem that it is difficult to easily manufacture the immersion diffraction element. In addition, since the shape to be processed is limited by the crystal orientation, there is a problem that the degree of freedom in designing the diffractive portion is not sufficient and it is difficult to improve the degree of freedom in optics.

An object of the present invention is to provide an immersion diffraction element and a method of manufacturing the immersion diffraction element that are easy to manufacture and can improve the degree of freedom in designing the diffraction section.

An immersion diffraction element according to the present invention includes a prism portion and a diffraction portion, and the prism portion and the diffraction portion are made of amorphous glass.

In the present invention, the amorphous glass preferably has a refractive index of 3.0 or more at a wavelength of 10 μm.

In the present invention, the amorphous glass is preferably chalcogenide glass.

In the present invention, even if the amorphous glass contains Te 4% to 80%, Ge 0% to 50% (but not including 0%), and Ga 0% to 20% in molar percentage. good.

In the present invention, the amorphous glass comprises, in terms of mole percentage, S 50% to 80%, Sb 0% to 40% (but not including 0%), and Ge 0% to 18% (but not including 0%). no), Sn 0% to 20%, and Bi 0% to 20%.

In the present invention, in the diffractive portion, it is preferable that the value obtained by dividing the angle R of the bottom point of the concave portion by the angle R of the apex portion of the convex portion is 2.0 or less. It is more preferable that the angle formed by the surfaces forming the bottom point of the concave portion is 60° or more and 120° or less.

In the present invention, it is preferable that the surface of the diffraction section is covered with a reflective film. More preferably, the reflective film is made of Au.

A method of manufacturing an immersion diffraction element according to the present invention is characterized by comprising the steps of preparing an amorphous glass and forming a diffraction portion by mold-pressing the amorphous glass.

In the present invention, when forming the unevenness of the diffraction portion, the amorphous Mold press molding of the glass is preferred. When forming the unevenness of the diffractive portion, the amorphous glass may be molded and press-molded so that the angle between the surfaces forming the bottom point portion of the concave portion is 60° or more and 120° or less. more preferred.

In the present invention, when forming the unevenness of the diffraction portion, the value obtained by dividing the angle R of the apex portion of the convex portion by the angle R of the bottom portion of the concave portion having a shape corresponding to the unevenness of the diffraction portion It is preferable that the amorphous glass is molded and press-molded using a press die in which the is 10.0 or less. More preferably, the amorphous glass is molded and press-molded using a press die in which the angles formed by the surfaces forming the apexes of the protrusions are 60° or more and 120° or less.

In the present invention, the amorphous glass preferably has a glass transition point of 140° C. or higher and 250° C. or lower.

In the present invention, when forming the diffraction portion, the amorphous glass is preferably press-molded at a temperature of +5°C to the glass transition temperature of the amorphous glass +50°C.

In the present invention, when forming the diffraction portion, it is preferable that the amorphous glass is mold-press molded using a press mold plated with nickel-phosphorus.

According to the present invention, it is possible to provide an immersion diffraction element and a method for manufacturing the immersion diffraction element, which are easy to manufacture and can improve the degree of freedom in designing the diffraction section.

FIG. 1 is a schematic cross-sectional view showing an immersion diffraction element according to a first embodiment of the invention. FIG. 2 is a schematic plan view showing a diffraction surface in the immersion diffraction element according to the first embodiment of the invention. FIG. 3 is a schematic cross-sectional view for explaining spectroscopy in the immersion diffraction element. 4 is an enlarged view of the diffractive portion in FIG. 3. FIG. FIG. 5 is a schematic cross-sectional view for explaining a press die used in the method for manufacturing an immersion diffraction element according to the first embodiment of the invention. FIG. 6 is a schematic cross-sectional view showing an immersion diffraction element according to a second embodiment of the invention. FIG. 7 is a schematic cross-sectional view showing an immersion diffraction element according to a third embodiment of the invention. FIG. 8 is a scanning electron microscope (SEM) photograph of the mold used in the experimental example. FIG. 9 is a scanning electron microscope (SEM) photograph of the mold used in the experimental example. FIG. 10 is a scanning electron microscope (SEM) photograph of the immersion diffraction element produced in Experimental Example. FIG. 11 is a scanning electron microscope (SEM) photograph of the immersion diffraction element produced in Experimental Example. FIG. 12 is a scanning electron microscope (SEM) photograph of the immersion diffraction element produced in Experimental Example.

Preferred embodiments are described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. Also, in each drawing, members having substantially the same function may be referred to by the same reference numerals.

[First Embodiment]
FIG. 1 is a schematic cross-sectional view showing an immersion diffraction element according to a first embodiment of the invention. Also, FIG. 2 is a schematic plan view showing a diffraction surface in the immersion diffraction element according to the first embodiment of the present invention. 1 is a schematic cross-sectional view along line II in FIG.

As shown in FIG. 1 , the immersion diffraction element 1 includes a prism section 2 and a diffraction section 4 . The prism section 2 and the diffraction section 4 are integrally provided.

The prism portion 2 has a triangular prism shape. The prism portion 2 has a first surface 2a, a second surface 2b, and a third surface 2c. The first surface 2a, the second surface 2b, and the third surface 2c correspond to the side surfaces of the triangular prism shape.

As shown in FIGS. 1 and 2, the first surface 2a of the prism portion 2 is provided with a plurality of diffraction grooves 3 periodically. The diffraction section 4 is thus configured. More specifically, the plurality of diffraction grooves 3 are provided so that the diffraction portion 4 has a stepped shape. The shape of the prism portion 2 is not particularly limited as long as it has a surface on which the diffraction portion 4 is provided.

The diffraction section 4 has a fourth surface 4a and a fifth surface 4b. By alternately and repeatedly providing the fourth surface 4a and the fifth surface 4b, the concave portions 4c and the convex portions 4d are alternately and repeatedly provided. Thereby, a stepped diffraction portion 4 is formed.

FIG. 3 is a schematic cross-sectional view for explaining spectroscopy in the immersion diffraction element. 4 is an enlarged view of the diffractive portion in FIG. 3. FIG. 3 and 4 are not hatched.

As shown in FIG. 3, the second surface 2b of the prism portion 2 is the incident portion of the immersion diffraction element 1. As shown in FIG. In addition, the diffraction portion 4 includes a bottom point portion 4c1 shown in FIG. More specifically, diffraction portion 4 includes a plurality of bottom point portions 4c1. As shown in FIG. 3, the light A enters from the second surface 2b, passes through the prism section 2, and reaches the diffraction section 4. As shown in FIG. Then, the light A is dispersed by being reflected and diffracted by each fourth surface 4a and each bottom point portion 4c1 in the diffraction portion 4. As shown in FIG. Dashed line arrows and dashed line arrows in FIG. 3 indicate examples of the dispersed light. The split light is emitted from the prism section 2 . As indicated by the wavy lines in FIG. 3, the wavelength of the light A inside the prism portion 2 is shorter than the wavelength of the light A outside the prism portion 2 . Therefore, it is possible to shorten the pitch of the diffraction grooves 3 required for spectroscopy. Therefore, in the immersion diffraction element 1, both improvement in wavelength resolution and miniaturization can be achieved.

In the immersion diffraction element 1 of this embodiment, the prism portion 2 and the diffraction portion 4 are made of amorphous glass. Therefore, manufacturing is easy, and the degree of freedom in designing the diffraction section 4 can be improved.

Conventionally, the diffraction portion of an immersion diffraction element is made of a crystal material such as single crystal Ge. Thus, when the diffraction section is made of a crystal material, the diffraction grooves are formed by processing the crystal material, such as cutting or etching. Therefore, there is a problem that it is difficult to easily manufacture the immersion diffraction element. Moreover, when the diffraction section is made of a crystal material, the processing shape is restricted by the crystal orientation, so there is a problem that the degree of freedom in designing the diffraction section is not sufficient and it is difficult to improve the optical degree of freedom.

On the other hand, in the immersion diffraction element 1 of this embodiment, the prism portion 2 and the diffraction portion 4 are made of amorphous glass. Therefore, the immersion diffraction element 1 can be easily formed by subjecting the prism portion 2 to mold press molding, as will be described later in the manufacturing method column. In addition, in the case of amorphous glass, since the processing shape is not restricted by the crystal orientation, the degree of freedom in designing the diffraction section 4 can be improved. Therefore, the immersion diffraction element 1 of this embodiment can improve the optical degree of freedom.

As used herein, the term "amorphous glass" refers to glass in which no crystalline peak is observed and a halo pattern peculiar to glass is observed as measured by powder X-ray diffraction.

In this embodiment, the refractive index at a wavelength of 10 μm of the amorphous glass forming the prism portion 2 and the diffraction portion 4 is preferably 3.0 or more, more preferably 3.1 or more, and still more preferably 3.2 or more. be. If the refractive index of the amorphous glass is equal to or higher than the above lower limit, the immersion diffraction element 1 can be further miniaturized. Although the upper limit of the refractive index of the amorphous glass is not particularly limited, it can be, for example, 4.1 or less due to the properties of the material.

The amorphous glass forming the prism portion 2 and the diffraction portion 4 is preferably chalcogenide glass. In this case, the refractive index of the amorphous glass can be further increased.

Above all, the amorphous glass preferably contains Te 4% to 80%, Ge 0% to 50% (but not including 0%), and Ga 0% to 20% in terms of molar percentage. . In this case, the refractive index of the amorphous glass can be further increased.

In the amorphous glass, the content of Te in terms of molar percentage is preferably 10% or more, more preferably 20% or more, particularly preferably 30% or more, more preferably 75% or less, and still more preferably 70%. It is below. When the content of Te in the amorphous glass is less than 4%, vitrification becomes difficult. On the other hand, when the Te content in the amorphous glass exceeds 80%, Te-based crystals precipitate from the glass, making it difficult to obtain the refractive index and transmittance that satisfy the characteristics of the immersion diffraction element 1. The surface quality of the immersion diffraction element 1 may deteriorate due to a large amount of Te evaporation during mold press molding.

In the amorphous glass, the Ge content is preferably 1% or more, more preferably 5% or more, more preferably 40% or less, and still more preferably 30% or less in terms of molar percentage. If the amorphous glass does not contain Ge, it becomes difficult to vitrify. On the other hand, when the Ge content in the amorphous glass exceeds 50%, Ge-based crystals precipitate from the glass, making it difficult to obtain the refractive index and transmittance that satisfy the characteristics of the immersion diffraction element 1. When the viscosity of the glass is increased during mold press molding, the followability of the shape of the diffraction section 4 to the press die 10 described later may be deteriorated.

In the amorphous glass, the content of Ga is preferably 0.1% or more, more preferably 1% or more, more preferably 15% or less, and still more preferably 10% or less in terms of molar percentage. By including Ga in the amorphous glass, the vitrification range can be broadened and the thermal stability (vitrification stability) of the glass can be further enhanced.

Alternatively, the amorphous glass is, in mole percentage, S 50%-80%, Sb 0%-40% (but not including 0%), Ge 0%-18% (but not including 0%), Sn A glass containing 0% to 20% Bi and 0% to 20% Bi is preferred. In this case, the refractive index of the amorphous glass can be further increased.

In the amorphous glass, the S content is more preferably 55% or more, more preferably 60% or more, more preferably 75% or less, and still more preferably 70% or less in terms of molar percentage. When the content of S in the amorphous glass is less than 50%, vitrification becomes difficult. On the other hand, when the content of S in the amorphous glass exceeds 80%, the weather resistance of the glass is lowered, which may limit the usage environment of the immersion diffraction element 1 .

In the amorphous glass, the Sb content is preferably 5% or more, more preferably 10% or more, more preferably 35% or less, and still more preferably 33% or less in terms of molar percentage. If the amorphous glass does not contain Sb, or if the content exceeds 40%, vitrification may become difficult.

In the amorphous glass, the Ge content is preferably 2% or more, more preferably 4% or more, and more preferably 15% or less in terms of molar percentage. If the glass does not contain Ge, it becomes difficult to vitrify. On the other hand, when the Ge content in the amorphous glass exceeds 18%, Ge-based crystals precipitate out of the glass, making it difficult to obtain the refractive index and transmittance that satisfy the characteristics of the immersion diffraction element 1. Also, when the viscosity of the glass is increased during mold press molding, there are cases where the followability of the shape of the diffraction section 4 to the press die 10, which will be described later, deteriorates.

In the amorphous glass, the Sn content is preferably 1% or more, more preferably 5% or more, more preferably 15% or less, and still more preferably 10% or less in terms of molar percentage. Sn in the amorphous glass is a component that promotes vitrification, but when the Sn content in the amorphous glass exceeds 20%, vitrification becomes difficult.

In the amorphous glass, the molar percentage of Bi content is preferably 0.5% or more, more preferably 2% or more, more preferably 10% or less, and still more preferably 8% or less. Bi in the amorphous glass is a component that reduces the energy required for vitrification of the raw material when the glass is melted. However, when the content of Bi in the amorphous glass exceeds 20%, Bi-based crystals are precipitated from the glass, making it difficult to obtain the refractive index and transmittance that satisfy the characteristics of the immersion diffraction element 1. There is

The density of the amorphous glass forming the prism portion 2 and the diffraction portion 4 is preferably 6.5 g/cm ³ or less, more preferably 6.3 g/cm ³ or less, and still more preferably 6.0 g/cm ³ or less. be. If the density of the amorphous glass satisfies the above range, the weight of the immersion diffraction element 1 can be further reduced.

In addition, the amorphous glass constituting the prism portion 2 and the diffraction portion 4 preferably has an internal transmittance of 80% or more, more preferably 85% or more, in an infrared wavelength range at a wavelength of 7.0 μm to 11.0 μm. Preferably it is 90% or more. In this case, desired optical performance can be obtained more reliably. The upper limit of the internal transmittance in the infrared wavelength region in the wavelength range of 7.0 μm to 11.0 μm can be set to 99.5%, for example. Here, the internal transmittance is for a wall thickness of 2.0 mm.

In this embodiment, in the diffraction portion 4, it is preferable that the bottom point portion 4c1 of the concave portion 4c has a shape that is sharper than the apex portion 4d1 of the convex portion 4d. Since the fourth surface 4a and the bottom point 4c1 of the recess 4c greatly affect the characteristic surface of the immersion diffraction element 1, the bottom point 4c1 of the recess 4c is sharper than the peak 4d1 of the projection 4d. That is, when the angle R (radius, μm) of the bottom point portion 4c1 of the concave portion 4c is R4c1, and the angle R (radius, μm) of the apex portion 4d1 of the convex portion 4d is R4d1, the value obtained by dividing R4c1 by R4d1 is By setting it to preferably 2.0 or less, more preferably 1.0 or less, the diffraction efficiency of the immersion diffraction element 1 can be further improved. The value of R4c1 is preferably 0.1 μm to 10 μm, and the value of R4d1 is preferably 5 μm to 20 μm.

Further, as shown in FIG. 3, the angle θ1 formed by the fourth surface 4a and the fifth surface 4b forming the bottom portion 4c1 of the recess 4c is preferably 60° or more, more preferably 65° or more, and further preferably 65° or more. It is preferably 70° or more, particularly preferably 80° or more, preferably 120° or less, more preferably 115° or less, still more preferably 110° or less, and particularly preferably 100° or less. The angle θ1 formed by the fourth surface 4a and the fifth surface 4b forming the bottom portion 4c1 of the recess 4c is preferably 90°±1°, more preferably 90°. In this case, the diffraction efficiency of the immersion diffraction element 1 can be further improved.

An example of a method for manufacturing the immersion diffraction element 1 will be described below.

(Production method)
In the manufacturing method of this embodiment, first, an amorphous glass is prepared. As the amorphous glass, the same amorphous glass as that constituting the prism portion 2 and the diffraction portion 4 can be used. As the amorphous glass, for example, chalcogenide glass with a glass composition of 60% S, 30% Sb, 5% Ge, and 5% Sn in terms of molar percentages, or a glass composition with a molar percentage of Te of 70%, A base glass made of chalcogenide glass of 25% Ge and 5% Ga is prepared. Next, the diffractive portion 4 is formed by mold-pressing the amorphous glass. Specifically, the prism portion 2 and the diffraction portion 4 can be formed by preparing a prism (precursor prism) made of amorphous glass and subjecting this precursor prism to mold press molding.

In the manufacturing method of the present embodiment, the diffractive portion 4 can be easily formed by mold-pressing the precursor prism. In addition, the amorphous glass can be transferred as described above, and the processed shape is not limited by the crystal orientation, so the degree of freedom in designing the diffraction section 4 can be improved. Therefore, in the manufacturing method of the present embodiment, the optical degree of freedom of the immersion diffraction element 1 can be improved.

In the present invention, when forming the unevenness of the diffraction portion 4, the angle R of the bottom point portion 4c1 of the concave portion 4c is R4c1, and the angle R of the apex portion 4d1 of the convex portion 4d is R4d1. is preferably 2.0 or less, more preferably 1.0 or less. As shown in FIG. 3, in the obtained diffraction portion 4, the fourth surface 4a and the bottom point portion 4c1 of the concave portion 4c greatly affect the characteristic surface of the immersion diffraction element 1. Therefore, R4c1 is divided by R4d1. By defining the values as described above, the diffraction efficiency of the immersion diffraction element 1 can be further improved. The value of R4c1 is preferably 0.1 μm to 10 μm, and the value of R4d1 is preferably 5 μm to 20 μm.

In the present invention, when forming the unevenness of the diffraction portion 4, the angle formed by the fourth surface 4a and the fifth surface 4b forming the bottom portion 4c1 of the concave portion 4c is 60° or more and 120° or less. It is preferable to mold-press the amorphous glass so as to obtain the following. The angle formed by the fourth surface 4a and the fifth surface 4b forming the bottom portion 4c1 of the recessed portion 4c is preferably 65° or more, more preferably 70° or more, and particularly preferably 80° or more. It is preferably 115° or less, more preferably 110° or less, and particularly preferably 100° or less. The angle formed by the fourth surface 4a and the fifth surface 4b forming the bottom portion 4c1 of the recess 4c is preferably 90°±1°, more preferably 90°. In this case, the diffraction efficiency of the immersion diffraction element 1 can be further improved.

FIG. 5 is a schematic cross-sectional view for explaining a press die used in the method for manufacturing an immersion diffraction element according to the first embodiment of the invention.

As shown in FIG. 5 , the press die 10 has a shape corresponding to the unevenness of the diffraction section 4 . In the press die 10, the apex 12a of the projection 12 is sharper than the bottom 11a of the recess 11. Assuming that the angle R is R11a, the value obtained by dividing R12a by R11a is preferably 10.0 or less, more preferably 8.0 or less. By molding and press-molding the amorphous glass using such a press die 10, the value obtained by dividing the above R4c1 by R4d1 in the diffraction portion 4 can more reliably be 10.0 or less, preferably 2.0. Below, it is more preferably 1.0 or less, and the diffraction efficiency of the immersion diffraction element 1 can be further improved. The value of R11a is preferably 1 μm to 20 μm, and the value of R12a is preferably 0.05 μm to 10 μm.

In addition, in the press die 10, the angle θ2 formed by the sixth surface 13 and the seventh surface 14 forming the apex portion 12a of the convex portion 12 is preferably 60° or more, more preferably 65° or more, more preferably 65° or more. is 70° or more, particularly preferably 80° or more, preferably 120° or less, more preferably 115° or less, even more preferably 110° or less, and particularly preferably 100° or less. The angle θ2 formed by the sixth surface 13 and the seventh surface 14 forming the apex portion 12a of the convex portion 12 is preferably 90°±1°, more preferably 90°. The angle formed by the fourth surface 4a and the fifth surface 4b forming the bottom point portion 4c1 of the concave portion 4c by press-molding amorphous glass using such a press die 10 is as described above. It can be adjusted within a preferable range, and the diffraction efficiency of the immersion diffraction element 1 can be further improved.

The material of the press die 10 is not particularly limited, but cemented carbide, STAVAX, HPM38, etc. can be used, for example. As the press die 10, a press die plated with nickel-phosphorus may be used.

In the present invention, when forming the diffractive portion 4, it is preferable to mold-press the amorphous glass at a temperature equal to or higher than the glass transition temperature of the amorphous glass +5°C and equal to or lower than the glass transition temperature +50°C. The temperature for the mold press molding of the amorphous glass is more preferably the glass transition temperature of the amorphous glass +10°C or higher and the glass transition temperature +45°C or lower, and more preferably the glass transition temperature of the amorphous glass +15°C or higher. , glass transition temperature + 40°C or less.

The glass transition point of the amorphous glass is preferably 140° C. or higher, more preferably 145° C. or higher, still more preferably 150° C. or higher, preferably 250° C. or lower, more preferably 245° C. or lower, further preferably 240° C. or higher. °C or less.

When the mold press molding is performed at the temperature as described above, the pressing can be performed at a lower temperature. Therefore, even when a large-sized amorphous glass is molded, the thermal variation is much less likely to occur. In addition, thermal strain that causes dimensional change can be made more difficult to occur.

In addition, nickel-phosphorus-plated press dies may become difficult to use due to crystallization at high temperatures, so they can be suitably used when pressing at low temperatures as described above. By using a nickel-phosphorus-plated press die, it becomes easier to obtain a specular surface of the press die, and the surface accuracy of the mold press molding can be further improved, so that the design freedom of the diffraction section 4 is further improved. can be made Here, as an example, a nickel-phosphorus plated press die is used, but the type of plating is not limited to this, and nickel-molybdenum plating, nickel-tungsten plating, or the like can be used.

(Experimental example)
In the experimental example, an immersion diffraction element was manufactured based on the method for manufacturing an immersion diffraction element according to the first embodiment of the present invention. Specifically, an immersion diffraction element was produced by mold-pressing amorphous glass under the conditions of a reduced pressure environment (degree of vacuum of 0.3 Pa), a temperature of 185°C, a press time of 1 minute, and a press pressure of 2 kN. . Chalcogenide glass containing 70% Te, 20% Ge, and 10% Ga in molar percentage was used as the amorphous glass.

8 and 9 are scanning electron microscope (SEM) photographs of the molds used in the experimental examples. FIG. 8 is a SEM photograph of the cross section of the diffraction surface forming portion of the mold used in the experimental example, and FIG. 9 is an enlarged view of the diffraction surface forming portion. A cemented carbide material (Cemented Carbide EF10, manufactured by Kyoritsu Gokin Seisakusho Co., Ltd.) was used as the material of the mold.

10 to 12 are scanning electron microscope (SEM) photographs of immersion diffraction elements fabricated in experimental examples. Note that FIG. 10 is an SEM photograph of the diffraction surface of the immersion diffraction element. FIG. 11 is a cross-sectional SEM photograph of the immersion diffraction element, and FIG. 12 is an enlarged view of the diffraction portion.

As shown in FIGS. 10 to 12, in the immersion diffraction element manufactured by mold press molding, chipping is less likely to occur in the diffraction portion 4 and the diffraction grooves 3. FIG. This point can be explained as follows.

A conventional immersion diffraction element obtained by directly cutting or polishing a crystalline material or an amorphous glass material has a problem that chipping is likely to occur in the diffraction portion. On the other hand, when a steel material such as a superhard material is subjected to cutting, polishing, or the like, chipping is less likely to occur in the diffraction portion. Therefore, by performing mold transfer to amorphous glass using a mold as shown in FIGS. 8 and 9, it is possible to provide the amorphous glass with a diffraction structure in which chipping is suppressed.

Thus, in the immersion diffraction element of this experimental example manufactured by mold press molding, chipping is less likely to occur in the diffraction portions 4 and the diffraction grooves 3 than in the case where the crystal material is cut, polished, or the like. It is possible to suppress the light scattering caused by , and it is possible to make it difficult to cause deterioration of optical characteristics (diffraction characteristics).

In addition, as shown in FIGS. 10 to 12, in the immersion diffraction element obtained by mold press molding, since processing chips due to chipping do not adhere to the diffraction portion 4 and the diffraction groove 3, after forming a reflective film, etc., which will be described later, In addition, it is possible to suppress peeling of the reflective film due to processing waste, thereby suppressing reflection loss and light scattering.

In addition, when the immersion diffraction element is manufactured by mold press molding as in this experimental example, it is difficult to generate processing waste due to chipping. Deterioration of the optical characteristics of the element can be made difficult to occur. More specifically, cleaning after cutting or polishing may damage the diffraction section during cleaning, or the aggregation of processing scraps or floating dust in the diffraction section or diffraction grooves may deteriorate the optical characteristics. However, this problem can be solved by manufacturing by mold press molding as in this experimental example.

[Second embodiment]
FIG. 6 is a schematic cross-sectional view showing an immersion diffraction element according to a second embodiment of the invention.

As shown in FIG. 6 , in the immersion diffraction element 21 , the surface of the diffraction section 4 is covered with a reflective film 22 . More specifically, the reflective film 22 covers the fourth surface 4 a and the fifth surface 4 b of the diffraction section 4 .

The material of the reflective film 22 is not particularly limited, but metal such as Au can be used. An appropriate dielectric multilayer film may be used as the reflective film 22 . The thickness of the reflective film 22 can be, for example, 1 μm or more and 10 μm or less. The reflective film 22 can be formed by vapor deposition or sputtering, for example. The reflective film 22 may use Si as its underlying film. Other points are the same as in the first embodiment.

Also in the immersion diffraction element 21 of the second embodiment, the prism portion 2 and the diffraction portion 4 are made of amorphous glass. Therefore, manufacturing is easy, and the degree of freedom in designing the diffraction section 4 can be improved.

Also, like the immersion diffraction element 21 , the surface of the diffraction section 4 may be covered with the reflective film 22 . In this case, the light that has entered the prism section 2 can be more reliably reflected by the diffraction section 4 and can be more reliably dispersed.

[Third Embodiment]
FIG. 7 is a schematic cross-sectional view showing an immersion diffraction element according to a third embodiment of the invention.

As shown in FIG. 7, in the immersion diffraction element 31, an antireflection film 32 is provided on the second main surface 2b of the prism portion 2. As shown in FIG.

The antireflection film 32 is preferably made of at least one selected from, for example, Ge, Si, fluoride, ZnSe, ZnS, and diamond-like carbon.

In addition, the antireflection film 32 can be formed by, for example, a vapor deposition method or a sputtering method. Also, the thickness of the antireflection film 32 can be set to, for example, 1.0 μm or more and 5.0 μm or less. Other points are the same as in the first embodiment.

Also in the immersion diffraction element 31 of the third embodiment, the prism portion 2 and the diffraction portion 4 are made of amorphous glass. Therefore, manufacturing is easy, and the degree of freedom in designing the diffraction section 4 can be improved.

Further, like the immersion diffraction element 31, an antireflection film 32 may be provided on the second main surface 2b of the prism portion 2. FIG. The second surface 2 b of the prism portion 2 is the incident portion of the immersion diffraction element 31 . Therefore, by providing the anti-reflection film 32 on this incident portion, the incident light is less likely to be reflected. Therefore, in this case, the utilization efficiency of light in the immersion diffraction element 31 can be further improved.

1, 21, 31... immersion diffraction element 2... prism parts 2a to 2c... first to third surfaces 3... diffraction grooves 4... diffraction parts 4a, 4b... fourth and fifth surfaces 4c, 11... concave parts 4c1, 11a Bottom point portions 4d, 12 Convex portions 4d1, 12a Vertex portion 10 Press molds 13, 14 Sixth and seventh surfaces 22 Reflective film 32 Antireflection film A Light R4c1 Bottom point portion Corner radius
R4d1 ... Corner R of the vertex
R11a ... corner R of the bottom point
R12a... Corner R of vertex part
θ1 Angle θ2 Angle

Claims (17)

comprising a prism section and a diffraction section,
The immersion diffraction element, wherein the prism section and the diffraction section are made of amorphous glass. 2. The immersion diffraction element according to claim 1, wherein said amorphous glass has a refractive index of 3.0 or more at a wavelength of 10 [mu]m. 3. The immersion diffraction element according to claim 1, wherein said amorphous glass is chalcogenide glass. 3. The amorphous glass according to claim 1 or 2, wherein the amorphous glass contains Te 4% to 80%, Ge 0% to 50% (but not including 0%), Ga 0% to 20%, in molar percentages. immersion diffraction element. The amorphous glass, in molar percentage, contains 50% to 80% S, 0% to 40% Sb (but not including 0%), 0% to 18% Ge (but not including 0%), and 0 Sn. % to 20% and Bi 0% to 20%. 3. The immersion diffraction element according to claim 1, wherein, in said diffractive portion, a value obtained by dividing the angle R of the bottom point portion of the concave portion by the angle R of the apex portion of the convex portion is 2.0 or less. 7. The immersion diffraction element according to claim 6, wherein the angles formed by the surfaces forming the bottom portions of the concave portions are 60[deg.] or more and 120[deg.] or less. 3. The immersion diffraction element according to claim 1, wherein the surface of said diffraction portion is covered with a reflective film. 9. The immersion diffraction element according to claim 8, wherein said reflective film is made of Au. providing an amorphous glass;
A method of manufacturing an immersion diffraction element, comprising: forming a diffraction portion by mold-pressing the amorphous glass. When forming the unevenness of the diffraction portion, the amorphous glass is mold-press molded so that the value obtained by dividing the angle R of the bottom point of the recess by the angle R of the top of the protrusion is 2.0 or less. 11. The method for manufacturing an immersion diffraction element according to claim 10, wherein When forming the unevenness of the diffraction portion, the amorphous glass is press-molded so that the angle between the surfaces forming the bottom point portion of the recess is 60° or more and 120° or less. Item 12. A method for manufacturing an immersion diffraction element according to Item 11. When forming the unevenness of the diffraction portion, it has a shape corresponding to the unevenness of the diffraction portion, and the value obtained by dividing the angle R of the apex portion of the convex portion by the angle R of the bottom portion of the concave portion is 10.0 or less. 12. The method of manufacturing an immersion diffraction element according to claim 10, wherein the amorphous glass is mold-press-molded using a press mold of . 14. The immersion diffraction diffraction method according to claim 13, wherein the amorphous glass is molded and press-molded using a press mold in which the angles formed by the surfaces forming the vertexes of the convex portions are 60° or more and 120° or less. A method for manufacturing an element. 12. The method for manufacturing an immersion diffraction element according to claim 10, wherein the amorphous glass has a glass transition point of 140[deg.] C. or higher and 250[deg.] C. or lower. 12. The amorphous glass according to claim 10 or 11, wherein when forming the diffraction portion, the amorphous glass is press-molded at a temperature of +5° C. or higher to the glass transition temperature of the amorphous glass, or +50° C. or lower. A method for manufacturing an immersion diffraction element. 12. The method of manufacturing an immersion diffraction element according to claim 10, wherein the amorphous glass is mold-press molded using a press die plated with nickel-phosphorus when forming the diffraction portion.

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