JP2015141202A

JP2015141202A - Zinc selenide optical element and method for manufacturing the same

Info

Publication number: JP2015141202A
Application number: JP2014011925A
Authority: JP
Inventors: 信治亀田; Shinji Kameda; 克仁吉田; Katsuto Yoshida; 賢一栗巣; Kenichi Kurisu
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2014-01-27
Filing date: 2014-01-27
Publication date: 2015-08-03

Abstract

PROBLEM TO BE SOLVED: To provide a ZnSe optical element and a method for manufacturing the optical element having high transmittance for light at a wavelength shorter than 543.5 nm and requiring no mechanical finishing of a surface by using ultraprecision cutting or polishing.SOLUTION: The ZnSe optical element in the form of a measurement sample having a thickness of 3 mm has a transmittance of 45% or more and 65% or less for light at a wavelength of 532 nm and surface roughness Ra of 0.03 μm or less in a portion transmitting the light.

Description

本発明は、赤外線透過窓や赤外線レンズとして使用されるセレン化亜鉛光学素子とその製造方法に関する。 The present invention relates to a zinc selenide optical element used as an infrared transmission window or an infrared lens and a method for manufacturing the same.

セレン化亜鉛（以下、ＺｎＳｅという。）は赤外線の透過特性に優れていることから、切断加工や板金に用いられている炭酸ガスレーザー用の透過窓やレンズ等の光学素子として使用されている。本用途ではレーザー光の出力が非常に高いことから、透過窓やレンズでの吸収を極めて小さく抑える必要がある。炭酸ガスレーザーは９．４μｍと１０．６μｍを中心とする２つの波長帯の赤外線レーザーを発光するが、前記赤外線レーザー光の吸収を極めて小さく抑えるために、高い純度と適切なＺｎ：Ｓｅの化学量論組成比が要求され、現在はＣＶＤ（ＣｈｅｍｉｃａｌＶａｐｏｕｒＤｅｐｏｓｉｔｉｏｎ）法で多結晶体が合成されている（特許文献１）。 Zinc selenide (hereinafter referred to as ZnSe) is excellent in infrared transmission characteristics, and thus is used as an optical element such as a transmission window or a lens for a carbon dioxide laser used in cutting and sheet metal. In this application, since the output of the laser beam is very high, it is necessary to suppress the absorption by the transmission window and the lens to be extremely small. The carbon dioxide laser emits infrared lasers in two wavelength bands centered at 9.4 μm and 10.6 μm. In order to minimize the absorption of the infrared laser light, high purity and appropriate Zn: Se chemistry are used. A stoichiometric composition ratio is required, and a polycrystal is currently synthesized by a CVD (Chemical Vapor Deposition) method (Patent Document 1).

一方、ＺｎＳｅ多結晶体を炭酸ガスレーザー用のレンズとして用いる際に、レーザー光を被加工材に正確に照射するための光学系の光軸調整が必要となるが、炭酸ガスレーザーは上述の通り非可視域の赤外線を発光するため、視認することができない。このため、光軸調整の際の操作性や安全性等の面から、非可視レーザーである炭酸ガスレーザーにヘリウムネオンレーザー等の可視レーザーを重畳することが行われている（特許文献２）。 On the other hand, when the ZnSe polycrystal is used as a lens for a carbon dioxide gas laser, it is necessary to adjust the optical axis of the optical system for accurately irradiating the workpiece with laser light. Since it emits infrared rays in a non-visible region, it cannot be visually recognized. For this reason, a visible laser such as a helium neon laser is superposed on a carbon dioxide gas laser that is an invisible laser in terms of operability and safety during optical axis adjustment (Patent Document 2).

また、ＺｎＳｅ光学素子の製造コストにおいては、ＺｎＳｅ多結晶体の素材コストと機械加工コストの占める割合が高く、これらのコストを低減することがＺｎＳｅ光学素子を普及させる上で重要である。超精密切削や研磨といった機械加工では、加工時間が長いだけでなく、大きな素材から光学素子の形状を削り出す必要があるため、少なからず加工屑として素材を無駄にしており、製造コストを高くする原因となっている。このため、ＣＶＤ法により合成したＺｎＳｅ多結晶体を用い、機械加工を採用せず、前記多結晶体を高温に保持した状態で加圧してプレス成形することにより、素子形状を作製することが提案されている（特許文献３）。 Moreover, in the manufacturing cost of the ZnSe optical element, the ratio of the material cost and the machining cost of the ZnSe polycrystal is high, and it is important to reduce these costs to spread the ZnSe optical element. In machining such as ultra-precise cutting and polishing, not only the processing time is long, but also it is necessary to cut out the shape of the optical element from a large material, so the material is wasted as processing waste and the manufacturing cost is increased. It is the cause. For this reason, it is proposed to use a ZnSe polycrystal synthesized by the CVD method, without using machining, and to press and press-mold the polycrystal while keeping it at a high temperature, thereby proposing a device shape. (Patent Document 3).

特公昭６１−２４４６５号公報Japanese Patent Publication No.61-24465 特開昭６０−２２３８５号公報Japanese Patent Laid-Open No. 60-22385 特開２０１３−１８６３９０号公報JP 2013-186390 A

ヘリウムネオンレーザーは、緑色（波長５４３．５ｎｍ）、黄色（波長５９４．１ｎｍ）、橙色（波長６１２．０ｎｍ）、赤色（波長６３２．８ｎｍ）等の可視レーザーを発振できるが、なかでも人間の視感度は緑色の光に対して最も高く、緑色レーザーを光軸調整に使用できれば、肉眼での光軸調整が容易になる。しかしながら、ＣＶＤ法で作製されたＺｎＳｅ多結晶体は、波長が５４３．５ｎｍより短い光では４５％未満の透過率しかなく、緑色レーザーを用いて光軸調整を行うには光が弱くて視認しにくいという問題があった。このため、５４３．５ｎｍより短い波長の光に対するＺｎＳｅ多結晶体の透過率の向上が求められていた。 The helium neon laser can oscillate visible lasers such as green (wavelength 543.5 nm), yellow (wavelength 594.1 nm), orange (wavelength 612.0 nm), and red (wavelength 632.8 nm). The sensitivity is the highest for green light. If a green laser can be used for optical axis adjustment, the optical axis adjustment with the naked eye becomes easy. However, the ZnSe polycrystal produced by the CVD method has a transmittance of less than 45% for light having a wavelength shorter than 543.5 nm, and the light is weak when visually adjusting the optical axis using a green laser. There was a problem that it was difficult. For this reason, the improvement of the transmittance | permeability of the ZnSe polycrystal with respect to the light of a wavelength shorter than 543.5 nm was calculated | required.

加えて、透過窓やレンズ等の光学素子の用途においては、素子の表面における光の散乱を抑制するために表面粗さＲａが０．０３μｍ以下であることが求められる。一方、特許文献３に記載された方法を用いて、ＣＶＤ法により合成したＺｎＳｅ多結晶体を高温に保持した状態で加圧してプレス成形した場合、レンズの曲率半径などマクロな寸法形状は所望の形状が得られるが、たとえＺｎＳｅ多結晶体に接する成形型の面を表面粗さＲａ０．０３μｍ以下にしたとしても、素子表面のミクロな領域における塑性変形が追随せず、成形型の表面粗さが素子の表面に十分転写されないため、成形後の素子の表面粗さＲａは０．０３μｍを超えるものとなっていた。このため、素子の表面粗さＲａを０．０３μｍ以下にするためには、ＺｎＳｅ多結晶体を高温に保持した状態で加圧してプレス成形した後、さらに素子の表面を超精密切削や研磨を用いて機械的に仕上げ加工する必要があった。 In addition, in applications of optical elements such as transmission windows and lenses, the surface roughness Ra is required to be 0.03 μm or less in order to suppress light scattering on the surface of the element. On the other hand, when the ZnSe polycrystalline body synthesized by the CVD method is pressed and press-molded while being kept at a high temperature using the method described in Patent Document 3, the macro dimension such as the curvature radius of the lens is desired. Although the shape can be obtained, even if the surface of the mold contacting the ZnSe polycrystal is made to have a surface roughness Ra of 0.03 μm or less, the plastic deformation in the micro area of the element surface does not follow, and the surface roughness of the mold Is not sufficiently transferred onto the surface of the element, the surface roughness Ra of the element after molding exceeds 0.03 μm. For this reason, in order to reduce the surface roughness Ra of the element to 0.03 μm or less, after press-molding the ZnSe polycrystalline body while maintaining a high temperature, the surface of the element is further subjected to ultraprecision cutting and polishing. It was necessary to use and finish mechanically.

本発明の第１の態様は、測定試料の厚み３ｍｍかつ反射防止コートをしない状態における波長５３２ｎｍの光の透過率が４５％以上６５％以下であり、前記光が透過する部分の表面粗さＲａが０．０３μｍ以下である、ＺｎＳｅ光学素子である。 In the first aspect of the present invention, the transmittance of light having a wavelength of 532 nm in a state where the thickness of the measurement sample is 3 mm and no antireflection coating is 45% or more and 65% or less, and the surface roughness Ra of the portion through which the light is transmitted. Is a ZnSe optical element having 0.03 μm or less.

本発明の第２の態様は、ＣＶＤ法によりＺｎＳｅ多結晶体を合成する工程と、前記ＺｎＳｅ多結晶体と接触する面の表面粗さＲａを０．００８μｍ以下とした上下押型の間に前記ＺｎＳｅ多結晶体を挟んだ後、上下押型のそれぞれの外径と胴型の内径とのクリアランスが、前記ＺｎＳｅ多結晶体を加圧変形する温度において０．０１０ｍｍ以下となるように設計した胴型内に収納し、不純物濃度が０．００１ｖｏｌ％以下かつ圧力が０．１気圧以上１０気圧以下の非酸化性ガス雰囲気中において、前記上下押型を加圧しながら１０５０℃を超え１１５０℃以下の温度に保持して、前記胴型と前記上下押型で構成される形状に前記ＺｎＳｅ多結晶体を変形させる工程と、を備えるＺｎＳｅ光学素子の製造方法である。 According to a second aspect of the present invention, the ZnSe is formed between a step of synthesizing a ZnSe polycrystal by a CVD method and a vertical pressing mold in which the surface roughness Ra of the surface in contact with the ZnSe polycrystal is 0.008 μm or less. After sandwiching the polycrystalline body, the clearance between the outer diameter of each of the upper and lower pressing molds and the inner diameter of the body mold is 0.010 mm or less at the temperature at which the ZnSe polycrystalline body is pressure-deformed. In a non-oxidizing gas atmosphere with an impurity concentration of 0.001 vol% or less and a pressure of 0.1 atm or more and 10 atm or less, while maintaining the temperature above 1050 ° C. and 1150 ° C. or less while pressurizing the upper and lower molds. And a step of deforming the ZnSe polycrystalline body into a shape constituted by the body mold and the vertical pressing mold.

上記の各態様によれば、緑色の波長域の光の透過率が高いＺｎＳｅ光学素子を提供することができ、また、ＺｎＳｅ多結晶体を高温に保持しながら加圧しプレス成形したままの状態で、光が透過する部分の表面粗さＲａを０．０３μｍ以下にすることが可能になる。 According to each of the above aspects, a ZnSe optical element having a high transmittance of light in the green wavelength region can be provided, and the ZnSe polycrystalline body is pressed and pressed while being kept at a high temperature. The surface roughness Ra of the portion through which light is transmitted can be made 0.03 μm or less.

加圧変形前のＺｎＳｅ多結晶体、上下押型と胴型の構成を示す断面模式図である。It is a cross-sectional schematic diagram which shows the structure of the ZnSe polycrystal body before and under pressure deformation, a vertical pressing die, and a trunk | drum type | mold. 加圧変形終了時のＺｎＳｅ多結晶体、上下押型と胴型の構成を示す断面模式図である。It is a cross-sectional schematic diagram which shows the structure of the ZnSe polycrystal at the time of completion | finish of a pressurization deformation | transformation, an up-down pressing die, and a trunk | drum.

以下、本発明の第１の態様であるＺｎＳｅ光学素子の実施形態について説明する。 Hereinafter, embodiments of the ZnSe optical element according to the first aspect of the present invention will be described.

本発明のＺｎＳｅ光学素子は、厚み３ｍｍの測定試料における波長５３２ｎｍの光の透過率が４５％以上６５％以下であり、前記光が透過する部分の表面粗さＲａが０．０３μｍ以下である。かかる透過率と光が透過する部分の表面粗さを有するＺｎＳｅ光学素子を、炭酸ガスレーザーの光学系に用いることにより、緑色レーザーを使用して肉眼で光軸調整を行うことができるようになり、光学素子の表面における光の散乱も抑制することができる。 In the ZnSe optical element of the present invention, the transmittance of light having a wavelength of 532 nm in a measurement sample having a thickness of 3 mm is 45% or more and 65% or less, and the surface roughness Ra of the portion through which the light is transmitted is 0.03 μm or less. By using a ZnSe optical element having such transmittance and surface roughness of a portion through which light is transmitted in an optical system of a carbon dioxide gas laser, the optical axis can be adjusted with the naked eye using a green laser. Further, light scattering on the surface of the optical element can also be suppressed.

人間の視感度は緑色の光に対して最も高く、波長が５００〜５６０ｎｍの緑色レーザーをレンズなどの光軸調整に使用できれば、肉眼での調整が容易になる。一般的な緑色のレーザー光としてはＮｄ−ＹＡＧレーザーの倍波に当たる５３２ｎｍの波長を持つものが多く、５３２ｎｍの波長の光に対して透過率を向上できれば光軸調整が容易になる。透過率は分光光度計を用いて測定することができる。分光光度計としては例えば日本分光社製のＶ−６７０が挙げられる。本発明のＺｎＳｅ光学素子の波長５３２ｎｍの光に対する透過率４５％以上６５％以下という値は、測定試料の厚み３ｍｍかつ反射防止コートをしない状態で測った値である。これに対して、ＣＶＤ法で合成した直後のＺｎＳｅ多結晶体の波長５３２ｎｍの光に対する透過率は、測定試料の厚み３ｍｍかつ反射防止コートをしない状態で４０％以上４５％未満である。 Human visual sensitivity is the highest for green light, and if a green laser with a wavelength of 500 to 560 nm can be used for optical axis adjustment of a lens or the like, adjustment with the naked eye becomes easy. Many common green laser beams have a wavelength of 532 nm, which is a harmonic of an Nd-YAG laser, and the optical axis can be easily adjusted if the transmittance can be improved with respect to light having a wavelength of 532 nm. The transmittance can be measured using a spectrophotometer. An example of the spectrophotometer is V-670 manufactured by JASCO Corporation. The value of the transmittance of 45% to 65% with respect to light having a wavelength of 532 nm of the ZnSe optical element of the present invention is a value measured in a state where the thickness of the measurement sample is 3 mm and no antireflection coating is applied. On the other hand, the transmittance of the ZnSe polycrystal immediately after being synthesized by the CVD method with respect to light having a wavelength of 532 nm is 40% or more and less than 45% when the thickness of the measurement sample is 3 mm and the antireflection coating is not applied.

本願において使用する表面粗さＲａは、ＪＩＳＢ０６０１２００１年で規定される一次元の算術平均粗さを二次元に拡張した概念であり、表面粗さ計を用いて測定することができる。例えば表面粗さ計としてＺｙｇｏ社のＮｅｗＶｉｅｗ１００を用いる場合、干渉計の組み込まれた２０倍対物レンズによってＺｎＳｅ表面の０．３２ｍｍ×０．６４ｍｍの任意の視野内の凹凸（高さ分布）を観察し、大きなうねり成分を除去した粗さ曲面の絶対値を積分して体積を求め、視野面積（０．２０４８ｍｍ^２）で除することによって視野内平均としての表面粗さＲａを算出する。以下、本願において表面粗さＲａと記載する場合、前記視野内平均としての表面粗さを意味している。 The surface roughness Ra used in the present application is a concept obtained by extending the one-dimensional arithmetic average roughness defined in JIS B 0601 2001 to two dimensions, and can be measured using a surface roughness meter. For example, when using Zygo's New View 100 as a surface roughness meter, the 20-times objective lens incorporating the interferometer allows the unevenness (height distribution) in an arbitrary visual field of 0.32 mm × 0.64 mm on the ZnSe surface. The surface roughness Ra as the average in the visual field is calculated by observing and calculating the volume by integrating the absolute value of the roughness curved surface from which the large undulation component has been removed and dividing by the visual field area (0.2048 mm ² ). Hereinafter, when described as surface roughness Ra in the present application, it means the surface roughness as the average in the visual field.

このとき、ＺｎＳｅ光学素子の光が透過する部分が機械加工されていないことが好ましい。ここで機械加工とは、旋盤や研磨機などの工作機械を使用し、切削工具や砥石などの加工工具を用いて加工することをいう。具体的にはＺｎＳｅ光学素子の光が透過する部分を超精密切削や研磨などの方法により、仕上げ加工することを指す。前記光が透過する部分の表面粗さＲａを０．０３μｍ以下にするために、表面を超精密切削や研磨を用いて機械的に仕上げ加工すると、製造コストが増大するからである。本発明者らは、ＣＶＤ法により合成したＺｎＳｅ多結晶体を高温に保持しながら加圧し、プレス成形する際の条件を制御することにより、ＺｎＳｅ多結晶体に接する面の表面粗さがＲａ０．０３μｍ以下である成形型を用いて、素子表面のミクロな領域における塑性変形を前記成形型の表面の凹凸に追随させ、成形型の表面粗さを素子の表面に転写することを可能にした。これにより、機械的な仕上げ加工をすることなく、ＺｎＳｅ多結晶体を高温に保持しながら加圧しプレス成形したままの状態で、光が透過する部分の表面粗さＲａを０．０３μｍ以下にすることが可能になった。前記制御の具体的な方法については後述する。 At this time, it is preferable that the portion of the ZnSe optical element that transmits light is not machined. Here, machining refers to machining using a machining tool such as a cutting tool or a grindstone using a machine tool such as a lathe or a polishing machine. Specifically, it means that a portion of the ZnSe optical element through which light passes is finished by a method such as ultra-precise cutting or polishing. This is because if the surface is mechanically finished using ultra-precise cutting or polishing in order to make the surface roughness Ra of the light transmitting portion 0.03 μm or less, the manufacturing cost increases. The inventors pressurize the ZnSe polycrystal synthesized by the CVD method while maintaining a high temperature, and control the conditions at the time of press molding, whereby the surface roughness of the surface in contact with the ZnSe polycrystal is Ra0. Using a molding die having a size of 03 μm or less, plastic deformation in a micro area on the surface of the element was made to follow the irregularities on the surface of the molding die, and the surface roughness of the molding die could be transferred to the surface of the element. As a result, the surface roughness Ra of the light transmitting portion is set to 0.03 μm or less in a state where the ZnSe polycrystalline body is pressed and pressed while maintaining a high temperature without mechanical finishing. It became possible. A specific method of the control will be described later.

上記のＺｎＳｅ多結晶体において、酸素の含有量が１ｐｐｍ以下であることが好ましい。酸素の含有量が１ｐｐｍを超えると、５３２ｎｍの波長において４５％以上の透過率を確保することが困難となるためである。ＺｎＳｅ多結晶体中に含まれる酸素の量は、ＳＩＭＳ（二次イオン質量分析計）で分析することにより、定量化できる。ＣＶＤ法により溶融亜鉛からの亜鉛蒸気とセレン化水素を反応させて作製されたＺｎＳｅ多結晶体は、不純物として数ｐｐｍ程度の酸素を含んでいる。このＺｎＳｅ多結晶体中の不純物酸素が５３２ｎｍの波長域の光の透過を阻害するメカニズムについては、現時点では必ずしも明らかではないが、本発明者らは、ＺｎＳｅ多結晶体中の不純物酸素を減少させることにより、５３２ｎｍの波長域の光の透過率が向上することを見出した。ＣＶＤ法により作製されたＺｎＳｅ多結晶体中の不純物酸素は、前記ＺｎＳｅ多結晶体を９２０℃以上１１５０℃以下の温度に保持して熱処理することにより、減少させることができる。前記熱処理の際には、その雰囲気を精密に制御する必要があるが、具体的な雰囲気制御の内容については後述する。 In the above ZnSe polycrystal, the oxygen content is preferably 1 ppm or less. This is because if the oxygen content exceeds 1 ppm, it becomes difficult to ensure a transmittance of 45% or more at a wavelength of 532 nm. The amount of oxygen contained in the ZnSe polycrystal can be quantified by analyzing with a SIMS (secondary ion mass spectrometer). A ZnSe polycrystal produced by reacting zinc vapor from molten zinc with hydrogen selenide by a CVD method contains about several ppm of oxygen as an impurity. The mechanism by which the impurity oxygen in the ZnSe polycrystal inhibits the transmission of light in the wavelength region of 532 nm is not necessarily clear at this time, but the present inventors reduce the impurity oxygen in the ZnSe polycrystal. As a result, it has been found that the transmittance of light in the wavelength region of 532 nm is improved. Impurity oxygen in the ZnSe polycrystal produced by the CVD method can be reduced by heat-treating the ZnSe polycrystal at a temperature of 920 ° C. or higher and 1150 ° C. or lower. At the time of the heat treatment, it is necessary to precisely control the atmosphere, and specific contents of the atmosphere control will be described later.

本発明の第２の態様である、ＺｎＳｅ光学素子の製造方法の一実施形態について、以下、工程順に説明する。 An embodiment of a method for producing a ZnSe optical element according to the second aspect of the present invention will be described below in the order of steps.

（ＺｎＳｅ多結晶体の合成工程）
本発明のＺｎＳｅ多結晶体は、高純度の材料が得られるという観点から、ＣＶＤ法を用いて作製することが好ましい。具体的には、搬送ガスとして純度９９．９９９％程度のアルゴンガスを用い、純度９９．９９９％程度のセレン化水素および純度９９．９９９％程度の溶融亜鉛からの亜鉛蒸気を、温度６００〜８００℃、雰囲気圧力１０ｋＰａ以下の反応炉内で反応させ、黒鉛基板上にＺｎＳｅ多結晶体を成長させることによって、合成することができる。 (Synthesis process of ZnSe polycrystal)
The ZnSe polycrystal of the present invention is preferably produced using a CVD method from the viewpoint that a high-purity material can be obtained. Specifically, argon gas having a purity of about 99.999% is used as a carrier gas, and hydrogen vapor from a hydrogen selenide having a purity of about 99.999% and a molten zinc having a purity of about 99.999% is heated to a temperature of 600 to 800. It can be synthesized by reacting in a reactor having a temperature of 10 ° C. and an atmospheric pressure of 10 kPa or less to grow a ZnSe polycrystal on a graphite substrate.

（加圧成形工程）
前記ＺｎＳｅ多結晶体から成形用の素材（以下、成形素材という。）を切り出し、成形素材と接触する面の表面粗さＲａを０．００２〜０．００８μｍとした上下押型の間に成形素材を挟んだ後、上下押型のそれぞれの外径と胴型の内径との直径差（以下、クリアランスという。）が、成形素材を加圧変形する温度において０．０１０ｍｍ以下となるように設計した胴型内に収納する（図１）。次に、不純物濃度が０．００１ｖｏｌ％以下かつ圧力が０．１気圧以上１０気圧以下の非酸化性ガス雰囲気中において、前記上下押型を加圧しながら１０５０℃を超え１１５０℃以下の温度に保持して、前記胴型と前記上下押型で構成される形状に前記成形素材を変形させる（図２）。 (Pressure forming process)
A molding material (hereinafter referred to as a molding material) is cut out from the ZnSe polycrystalline body, and the molding material is placed between the upper and lower molds having a surface roughness Ra of 0.002 to 0.008 μm on the surface in contact with the molding material. After sandwiching, the barrel die designed so that the difference in diameter (hereinafter referred to as clearance) between the outer diameter of each of the upper and lower pressing molds and the inner diameter of the barrel mold is 0.010 mm or less at the temperature at which the molding material is pressure-deformed. It is housed inside (FIG. 1). Next, in a non-oxidizing gas atmosphere with an impurity concentration of 0.001 vol% or less and a pressure of 0.1 atm or more and 10 atm or less, the upper and lower pressing molds are maintained at a temperature exceeding 1050 ° C. and not exceeding 1150 ° C. Then, the molding material is deformed into a shape constituted by the body mold and the vertical pressing mold (FIG. 2).

このとき、１０５０℃を超え１１５０℃以下の温度に保持することにより、成形素材の表面が昇華し、微細な欠陥が導入されることによって前記表面が塑性変形しやすくなる。このため加圧成形の際に、成形素材表面の微細な凹凸が押し潰され、成形素材の表面が上下押型の表面粗さに倣うため、加圧成形後のＺｎＳｅ光学素子の表面粗さが改善する。ただし、成形素材が過度に昇華しないよう、上下押型のそれぞれの外径と胴型の内径とのクリアランスが、成形素材を加圧変形する温度において０．０１０ｍｍ以下となるように設計した成形型を用いて、密閉度の高い空間内で成形素材を変形させる必要がある。前記クリアランスが成形素材を加圧変形する温度において０．０１０ｍｍを超える場合、成形素材が過度に昇華してしまい、所望の光学素子が得られないことがある。前記成形型を用いる場合、１０５０℃以下の温度では表面の昇華、微細な欠陥導入が不十分となり、成形素材表面の微細な凹凸を押し潰すことができず、成形素材の表面が上下押型の表面粗さに倣わないため、加圧成形後のＺｎＳｅ光学素子の表面粗さが大きくなることがある。逆に、１１５０℃を超える温度で加圧成形すると、たとえ前記成形型を用いたとしても、成形素材が過度に昇華してしまい、所望の光学素子が得られないことがある。 At this time, the surface of the molding material is sublimated by being maintained at a temperature exceeding 1050 ° C. and not higher than 1150 ° C., and the surface is easily plastically deformed by introducing fine defects. For this reason, the surface roughness of the ZnSe optical element after pressure molding is improved because the fine irregularities on the surface of the molding material are crushed during pressure molding, and the surface of the molding material follows the surface roughness of the upper and lower molds. To do. However, in order to prevent the molding material from being excessively sublimated, a molding die designed so that the clearance between the outer diameter of each of the upper and lower pressing molds and the inner diameter of the body mold is 0.010 mm or less at the temperature at which the molding material is subjected to pressure deformation. It is necessary to deform the molding material in a space with a high degree of sealing. When the clearance exceeds 0.010 mm at the temperature at which the molding material is pressure-deformed, the molding material is excessively sublimated, and a desired optical element may not be obtained. When using the mold, sublimation of the surface and introduction of fine defects are insufficient at a temperature of 1050 ° C. or less, and the fine irregularities on the surface of the molding material cannot be crushed. Since it does not follow the roughness, the surface roughness of the ZnSe optical element after pressure molding may increase. On the other hand, when pressure molding is performed at a temperature exceeding 1150 ° C., even if the molding die is used, the molding material is excessively sublimated, and a desired optical element may not be obtained.

加圧成形の際に、成形素材の表面が上下押型の表面粗さに倣い易くする目的で、ＺｎＳｅ多結晶体から切り出した成形素材の上下面を、表面粗さＲａ０．０３〜０．０８μｍに両面研磨することが好ましい。 For the purpose of facilitating the surface of the molding material to follow the surface roughness of the upper and lower pressing molds during the pressure molding, the upper and lower surfaces of the molding material cut out from the ZnSe polycrystal are made to have a surface roughness Ra of 0.03 to 0.08 μm. It is preferable to perform double-side polishing.

加圧成形は、不純物濃度が０．００１ｖｏｌ％以下、かつ圧力が０．１気圧以上１０気圧以下の非酸化性ガス雰囲気中で行う。非酸化性ガスとしては、窒素ガス、アルゴンガス、水素ガスまたはこれらの混合ガスを用いることができる。１０５０℃を超え１１５０℃以下の温度に保持することにより、ＣＶＤ法により合成したＺｎＳｅ多結晶体中に数ｐｐｍのオーダーで含有されていた不純物酸素を、１ｐｐｍ以下に減少させることができ、これに伴って、加圧成形後のＺｎＳｅ多結晶体の５３２ｎｍの波長の光の透過率を、４５％以上６５％以下に増大させることが可能になる。このとき、非酸化性ガスの不純物濃度を０．００１ｖｏｌ％以下、かつ雰囲気圧力を０．１気圧以上１０気圧以下とするのは、非酸化性ガス雰囲気中に不純物として含まれる酸素ガスの分圧を抑えるためである。非酸化性ガスの不純物濃度が０．００１ｖｏｌ％を超えるか、あるいは雰囲気圧力が１０気圧を超えるような場合には、非酸化性ガス雰囲気中に不純物として含まれる酸素ガスの分圧が高くなり、ＺｎＳｅ多結晶体中からの不純物酸素の離脱が十分に進行せず、熱処理後のＺｎＳｅ多結晶体中の不純物酸素を１ｐｐｍ以下に減少させるのが困難になることがある。一方、雰囲気圧力が０．１気圧未満の場合、前記成形型を用いたとしても、１０５０℃を超え１１５０℃以下の温度に保持する際に、ＺｎＳｅが過度に昇華する可能性があるため、雰囲気圧力は０．１気圧以上とすることが好ましい。 The pressure molding is performed in a non-oxidizing gas atmosphere having an impurity concentration of 0.001 vol% or less and a pressure of 0.1 to 10 atm. Nitrogen gas, argon gas, hydrogen gas, or a mixed gas thereof can be used as the non-oxidizing gas. By maintaining the temperature above 1050 ° C. and below 1150 ° C., the impurity oxygen contained in the order of several ppm in the ZnSe polycrystal synthesized by the CVD method can be reduced to 1 ppm or less. Along with this, it becomes possible to increase the light transmittance of the wavelength of 532 nm of the ZnSe polycrystalline body after pressure molding to 45% or more and 65% or less. At this time, the impurity concentration of the non-oxidizing gas is 0.001 vol% or less and the atmospheric pressure is 0.1 to 10 atm because the partial pressure of oxygen gas contained as impurities in the non-oxidizing gas atmosphere It is for suppressing. When the impurity concentration of the non-oxidizing gas exceeds 0.001 vol% or the atmospheric pressure exceeds 10 atm, the partial pressure of the oxygen gas contained as impurities in the non-oxidizing gas atmosphere increases, Desorption of impurity oxygen from the ZnSe polycrystal does not proceed sufficiently, and it may be difficult to reduce the impurity oxygen in the ZnSe polycrystal after heat treatment to 1 ppm or less. On the other hand, when the atmospheric pressure is less than 0.1 atm, even if the mold is used, ZnSe may excessively sublimate when held at a temperature exceeding 1050 ° C. and not exceeding 1150 ° C. The pressure is preferably 0.1 atm or more.

加圧成形の際には、成形素材に後述する所定の圧力を加えた状態で、１０５０℃を超え１１５０℃以下の温度に１０分以上保持することが好ましい。保持時間が１０分未満の場合、ＺｎＳｅ多結晶体中からの不純物酸素の離脱が十分に進行せず、加圧成形後のＺｎＳｅ多結晶体中の不純物酸素を１ｐｐｍ以下に減少させるのが困難になることがある。また、保持時間が１０分未満では、成形素材表面の微細な凹凸を十分に押し潰すことができず、成形素材の表面が上下押型の表面粗さに倣わないことがあり、加圧成形後のＺｎＳｅ光学素子の表面粗さが大きくなることがある。 At the time of pressure molding, it is preferable to hold at a temperature exceeding 1050 ° C. and not exceeding 1150 ° C. for 10 minutes or more in a state where a predetermined pressure described later is applied to the molding material. When the holding time is less than 10 minutes, the release of impurity oxygen from the ZnSe polycrystal does not proceed sufficiently, and it is difficult to reduce the impurity oxygen in the ZnSe polycrystal after pressure molding to 1 ppm or less. May be. In addition, if the holding time is less than 10 minutes, the fine irregularities on the surface of the molding material cannot be sufficiently crushed, and the surface of the molding material may not follow the surface roughness of the upper and lower molds. The surface roughness of the ZnSe optical element may increase.

さらに、加圧成形工程において、１０５０℃を超え１１５０℃以下の温度に保持する際に、ＺｎＳｅ多結晶体に５０ＭＰａ以上８０ＭＰａ以下の圧力を加えることが好ましい。このとき、プレス成形用の上下一対の型の間に成形素材をセットし、上下方向に荷重を加えることにより、成形素材を加圧することができる。成形型の材料としては、黒鉛やグラッシーカーボン、シリコンカーバイド、窒化ケイ素等の熱処理温度においても耐熱性のある材料を用いる。５０ＭＰａ未満の圧力では、成形素材表面の微細な凹凸を十分に押し潰すことができず、成形素材の表面が上下押型の表面粗さに倣わないことがあり、加圧成形後のＺｎＳｅ光学素子の表面粗さが大きくなることがある。一方、８０ＭＰａを超える圧力を加えると、成形素材が破損することがあるため、加圧成形において加える圧力は、５０ＭＰａ以上８０ＭＰａ以下であることが好ましい。 Furthermore, it is preferable to apply a pressure of 50 MPa or more and 80 MPa or less to the ZnSe polycrystal when the temperature is maintained at a temperature exceeding 1050 ° C. and not exceeding 1150 ° C. in the pressure molding step. At this time, the molding material can be pressurized by setting a molding material between a pair of upper and lower molds for press molding and applying a load in the vertical direction. As a material of the mold, a material having heat resistance even at a heat treatment temperature such as graphite, glassy carbon, silicon carbide, silicon nitride or the like is used. If the pressure is less than 50 MPa, fine irregularities on the surface of the molding material cannot be sufficiently crushed, and the surface of the molding material may not follow the surface roughness of the upper and lower pressing molds. The surface roughness of may increase. On the other hand, if a pressure exceeding 80 MPa is applied, the molding material may be damaged. Therefore, the pressure applied in the pressure molding is preferably 50 MPa or more and 80 MPa or less.

本発明の第３の態様である、ＺｎＳｅ光学素子の製造方法の他の実施形態について、以下に説明する。 Another embodiment of the method for producing a ZnSe optical element according to the third aspect of the present invention will be described below.

本発明の第２の態様であるＺｎＳｅ光学素子の製造方法の、ＺｎＳｅ多結晶体の合成工程に記載したのと同じ製造方法により、ＺｎＳｅ多結晶体を合成する。ＺｎＳｅ多結晶体から成形素材を切り出した後、成形素材の上下押型と接触する面、および表面粗さＲａを０．００２〜０．００８μｍとした上下押型の成形素材と接触する面の少なくとも一方に、粒径１０９μｍ以下のＺｎＳｅ粉末を散布した後、前記成形素材を上下押型で挟んで胴型内に収納する（図１）。次に、不純物濃度が０．００１ｖｏｌ％以下かつ圧力が０．１気圧以上１０気圧以下の非酸化性ガス雰囲気中において、前記上下押型を加圧しながら９２０℃以上１０５０℃以下の温度に保持して、前記胴型と前記上下押型で構成される形状に前記成形素材を変形させる（図２）。 A ZnSe polycrystalline body is synthesized by the same manufacturing method as described in the ZnSe polycrystalline body synthesizing step of the ZnSe optical element manufacturing method according to the second aspect of the present invention. After cutting the molding material from the ZnSe polycrystal, at least one of the surface that contacts the upper and lower pressing mold of the molding material and the surface that contacts the molding material of the upper and lower pressing mold whose surface roughness Ra is 0.002 to 0.008 μm After spraying ZnSe powder having a particle size of 109 μm or less, the molding material is sandwiched between upper and lower pressing molds and stored in a barrel mold (FIG. 1). Next, in a non-oxidizing gas atmosphere having an impurity concentration of 0.001 vol% or less and a pressure of 0.1 to 10 atm, the upper and lower pressing molds are maintained at a temperature of 920 to 1050 ° C. while being pressed. Then, the molding material is deformed into a shape constituted by the body mold and the vertical pressing mold (FIG. 2).

このとき、ＪＩＳ規格の１５０メッシュ（目開き１０９μｍ）の篩を用いて、ＺｎＳｅ粉末を篩分することにより、粒径１０９μｍ以下のＺｎＳｅ粉末を得ることができる。成形素材が例えば直径１０ｍｍの円盤形状の場合、成形素材の表面または成形素材と接触する上下押型の表面に、粒径１０９μｍ以下のＺｎＳｅ粉末を０．０１〜１ｇ程度散布した後、成形素材を上下押型で挟んで９２０℃以上１０５０℃以下の温度に保持しながら加圧成形する。加圧成形の際に、成形素材と上下押型の間に挟み込まれたＺｎＳｅ粉末は、成形素材表面の凹みに入り込み凹みを埋めると共に、ＺｎＳｅ粉末自身も体積拡散が起こって焼結体となる。このため成形素材の表面に新たにＺｎＳｅ焼結体の薄い層が形成されて上下押型の表面粗さに倣うため、加圧成形後のＺｎＳｅ光学素子の表面粗さが改善する。９２０℃未満の温度ではＺｎＳｅ粉末の焼結が十分に進行しないため、成形素材の表面が上下押型の表面粗さに倣わず、加圧成形後のＺｎＳｅ光学素子の表面粗さが大きくなることがある。逆に、１０５０℃を超える温度で加圧成形すると、ＺｎＳｅ粉末が昇華してしまい焼結が阻害されるため、加圧成形後のＺｎＳｅ光学素子の表面粗さが大きくなることがある。 At this time, a ZnSe powder having a particle size of 109 μm or less can be obtained by sieving the ZnSe powder using a JIS standard 150 mesh (aperture 109 μm) sieve. For example, when the molding material is a disk shape having a diameter of 10 mm, about 0.01 to 1 g of ZnSe powder having a particle size of 109 μm or less is sprayed on the surface of the molding material or the surface of the upper and lower molds in contact with the molding material. It press-molds, hold | maintaining at the temperature of 920 degreeC or more and 1050 degrees C or less by pinching with a pressing die. At the time of pressure molding, the ZnSe powder sandwiched between the molding material and the upper and lower molds enters into the recess on the surface of the molding material and fills the recess, and the ZnSe powder itself also undergoes volume diffusion and becomes a sintered body. For this reason, a thin layer of a ZnSe sintered body is newly formed on the surface of the molding material to follow the surface roughness of the upper and lower pressing molds, so that the surface roughness of the ZnSe optical element after pressure molding is improved. Since the sintering of ZnSe powder does not proceed sufficiently at temperatures below 920 ° C., the surface of the molding material does not follow the surface roughness of the upper and lower molds, and the surface roughness of the ZnSe optical element after pressure molding increases. There is. Conversely, when pressure molding is performed at a temperature exceeding 1050 ° C., the ZnSe powder sublimates and sintering is hindered, so that the surface roughness of the ZnSe optical element after pressure molding may increase.

加圧成形の際に成形素材と上下押型の間にＺｎＳｅ粉末を挟み込むため、上下押型のそれぞれの外径と胴型の内径とのクリアランスが、成形素材を加圧変形する温度において０．０１０ｍｍ以下となるように設計したクリアランスの狭い成形型を用いると、加圧成形中に前記クリアランスにＺｎＳｅ粉末が入り込み、上下押型と胴型が噛み込んで動かなくなることがある。このため、成形素材と上下押型の間にＺｎＳｅ粉末を挟み込んで加圧成形する場合には、前記クリアランスが成形素材を加圧変形する温度において０．０１０ｍｍを超えるように、クリアランスを広めに設計することが好ましい。その結果、成形型の密閉度が悪くなり、１０５０℃を超える温度で加圧成形すると、ＺｎＳｅ粉末が昇華し易くなる。 Since the ZnSe powder is sandwiched between the molding material and the upper and lower pressing molds during pressure molding, the clearance between the outer diameter of each of the upper and lower pressing molds and the inner diameter of the barrel mold is 0.010 mm or less at the temperature at which the molding material is pressure-deformed. If a molding die with a narrow clearance designed so as to be used is used, ZnSe powder may enter the clearance during pressure molding, and the upper and lower pressing molds and the body mold may get stuck and may not move. For this reason, when the pressure is formed by sandwiching the ZnSe powder between the molding material and the upper and lower molds, the clearance is designed to be wide so that the clearance exceeds 0.010 mm at the temperature at which the molding material is pressure-deformed. It is preferable. As a result, the sealing degree of the mold becomes poor, and when pressure molding is performed at a temperature exceeding 1050 ° C., the ZnSe powder is easily sublimated.

加圧成形は、不純物濃度が０．００１ｖｏｌ％以下、かつ圧力が０．１気圧以上１０気圧以下の非酸化性ガス雰囲気中で行う。非酸化性ガスとしては、窒素ガス、アルゴンガス、水素ガスまたはこれらの混合ガスを用いることができる。９２０℃以上１０５０℃以下の温度に保持することにより、ＣＶＤ法により合成したＺｎＳｅ多結晶体中に数ｐｐｍのオーダーで含有されていた不純物酸素を、１ｐｐｍ以下に減少させることができ、これに伴って、加圧成形後のＺｎＳｅ多結晶体の５３２ｎｍの波長の光の透過率を、４５％以上６５％以下に増大させることが可能になる。 The pressure molding is performed in a non-oxidizing gas atmosphere having an impurity concentration of 0.001 vol% or less and a pressure of 0.1 to 10 atm. Nitrogen gas, argon gas, hydrogen gas, or a mixed gas thereof can be used as the non-oxidizing gas. By maintaining the temperature at 920 ° C. or more and 1050 ° C. or less, the impurity oxygen contained in the ZnSe polycrystal synthesized by the CVD method on the order of several ppm can be reduced to 1 ppm or less. Thus, it becomes possible to increase the light transmittance of the wavelength of 532 nm of the ZnSe polycrystalline body after pressure molding to 45% or more and 65% or less.

このとき、非酸化性ガスの不純物濃度を０．００１ｖｏｌ％以下、かつ雰囲気圧力を０．１気圧以上１０気圧以下とするのは、非酸化性ガス雰囲気中に不純物として含まれる酸素ガスの分圧を抑えるためである。非酸化性ガスの不純物濃度が０．００１ｖｏｌ％を超えるか、あるいは雰囲気圧力が１０気圧を超えるような場合には、非酸化性ガス雰囲気中に不純物として含まれる酸素ガスの分圧が高くなり、ＺｎＳｅ多結晶体中からの不純物酸素の離脱が十分に進行せず、加圧成形後のＺｎＳｅ多結晶体中の不純物酸素を１ｐｐｍ以下に減少させるのが困難になることがある。一方、雰囲気圧力が０．１気圧未満の場合、９２０℃以上１０５０℃以下の温度に保持する際に、成形素材の表面または成形素材と接触する上下押型の表面に散布したＺｎＳｅ粉末の分解・昇華が激しくなり、ＺｎＳｅ粉末の焼結が阻害されるため、加圧成形後のＺｎＳｅ光学素子の表面粗さが大きくなることがある。 At this time, the impurity concentration of the non-oxidizing gas is 0.001 vol% or less and the atmospheric pressure is 0.1 to 10 atm because the partial pressure of oxygen gas contained as impurities in the non-oxidizing gas atmosphere It is for suppressing. When the impurity concentration of the non-oxidizing gas exceeds 0.001 vol% or the atmospheric pressure exceeds 10 atm, the partial pressure of the oxygen gas contained as impurities in the non-oxidizing gas atmosphere increases, The separation of impurity oxygen from the ZnSe polycrystal does not proceed sufficiently, and it may be difficult to reduce the impurity oxygen in the ZnSe polycrystal after pressure molding to 1 ppm or less. On the other hand, when the atmospheric pressure is less than 0.1 atm, decomposition / sublimation of ZnSe powder sprayed on the surface of the molding material or the surface of the upper and lower molds contacting the molding material when the temperature is maintained at 920 ° C. or more and 1050 ° C. or less. Since the sintering of ZnSe powder is hindered, the surface roughness of the ZnSe optical element after pressure molding may increase.

加圧成形の際には、成形素材に後述する所定の圧力を加えた状態で、９２０℃以上１０５０℃以下の温度に１０分以上保持することが好ましい。保持時間が１０分未満の場合、ＺｎＳｅ多結晶体中からの不純物酸素の離脱が十分に進行せず、加圧成形後のＺｎＳｅ多結晶体中の不純物酸素を１ｐｐｍ以下に減少させるのが困難になることがある。また、保持時間が１０分未満では、成形素材表面の微細な凹凸を十分に押し潰すことができず、成形素材の表面が上下押型の表面粗さに倣わないことがあり、加圧成形後のＺｎＳｅ光学素子の表面粗さが大きくなることがある。 At the time of pressure molding, it is preferable to hold at a temperature of 920 ° C. or higher and 1050 ° C. or lower for 10 minutes or more in a state where a predetermined pressure described later is applied to the molding material. When the holding time is less than 10 minutes, the release of impurity oxygen from the ZnSe polycrystal does not proceed sufficiently, and it is difficult to reduce the impurity oxygen in the ZnSe polycrystal after pressure molding to 1 ppm or less. May be. In addition, if the holding time is less than 10 minutes, the fine irregularities on the surface of the molding material cannot be sufficiently crushed, and the surface of the molding material may not follow the surface roughness of the upper and lower molds. The surface roughness of the ZnSe optical element may increase.

さらに、加圧成形工程において、９２０℃以上１０５０℃以下の温度に保持する際に、ＺｎＳｅ多結晶体に５０ＭＰａ以上８０ＭＰａ以下の圧力を加えることが好ましい。このとき、プレス成形用の上下一対の型の間に成形素材をセットし、上下方向に荷重を加えることにより、成形素材を加圧することができる。成形型の材料としては、黒鉛やグラッシーカーボン、シリコンカーバイド、窒化ケイ素等の熱処理温度においても耐熱性のある材料を用いる。５０ＭＰａ未満の圧力では、成形素材表面の微細な凹凸を十分に押し潰すことができず、成形素材の表面が上下押型の表面粗さに倣わないことがあり、加圧成形後のＺｎＳｅ光学素子の表面粗さが大きくなることがある。一方、８０ＭＰａを超える圧力を加えると、成形素材が破損することがあるため、加圧成形において加える圧力は、５０ＭＰａ以上８０ＭＰａ以下であることが好ましい。 Furthermore, in the pressure molding step, it is preferable to apply a pressure of 50 MPa or more and 80 MPa or less to the ZnSe polycrystal when the temperature is maintained at 920 ° C. or more and 1050 ° C. or less. At this time, the molding material can be pressurized by setting a molding material between a pair of upper and lower molds for press molding and applying a load in the vertical direction. As a material of the mold, a material having heat resistance even at a heat treatment temperature such as graphite, glassy carbon, silicon carbide, silicon nitride or the like is used. If the pressure is less than 50 MPa, fine irregularities on the surface of the molding material cannot be sufficiently crushed, and the surface of the molding material may not follow the surface roughness of the upper and lower pressing molds. The surface roughness of may increase. On the other hand, if a pressure exceeding 80 MPa is applied, the molding material may be damaged. Therefore, the pressure applied in the pressure molding is preferably 50 MPa or more and 80 MPa or less.

本発明の第４の態様である、ＺｎＳｅ光学素子の製造方法のさらに別の実施形態について、以下に説明する。 Still another embodiment of the method for producing a ZnSe optical element according to the fourth aspect of the present invention will be described below.

本発明の第２の態様であるＺｎＳｅ光学素子の製造方法の、ＺｎＳｅ多結晶体の合成工程に記載したのと同じ製造方法により、ＺｎＳｅ多結晶体を合成する。前記ＺｎＳｅ多結晶体から成形素材を切り出し、成形素材と接触する面の表面粗さＲａを０．００２〜０．００８μｍとした上下押型の間に成形素材を挟んだ後、胴型内に収納する（図１）。次に、１００Ｐａ以上２０００Ｐａ以下の真空中において、前記上下押型を加圧しながら９２０℃以上１０５０℃以下の温度に保持して、前記胴型と前記上下押型で構成される形状に前記成形素材を変形させる（図２）。 A ZnSe polycrystalline body is synthesized by the same manufacturing method as described in the ZnSe polycrystalline body synthesizing step of the ZnSe optical element manufacturing method according to the second aspect of the present invention. A molding material is cut out from the ZnSe polycrystalline body, and the molding material is sandwiched between upper and lower pressing dies having a surface roughness Ra of 0.002 to 0.008 μm on the surface in contact with the molding material, and then stored in the body mold. (FIG. 1). Next, in a vacuum of 100 Pa or more and 2000 Pa or less, the upper and lower pressing molds are held at a temperature of 920 ° C. or higher and 1050 ° C. or lower while being pressed, and the molding material is deformed into a shape constituted by the barrel mold and the upper and lower pressing molds. (FIG. 2).

このとき、１００Ｐａ以上２０００Ｐａ以下の真空中において、９２０℃以上１０５０℃以下の温度に保持することにより、成形素材の表面が昇華し、微細な欠陥が導入されることによって前記表面が塑性変形しやすくなる。このため加圧成形の際に、成形素材表面の微細な凹凸が押し潰され、成形素材の表面が上下押型の表面粗さに倣うため、加圧成形後のＺｎＳｅ光学素子の表面粗さが改善する。真空度が１００Ｐａ未満の場合、成形素材が過度に昇華してしまい、成形素材の重量減少が無視できなくなって、所望の光学素子が得られないことがある。逆に、真空度が２０００Ｐａを超える場合には、成形素材表面の昇華、微細な欠陥導入が不十分となり、成形素材表面の微細な凹凸を押し潰すことができず、成形素材の表面が上下押型の表面粗さに倣わないため、加圧成形後のＺｎＳｅ光学素子の表面粗さが大きくなることがある。このため、真空ポンプを用いて加圧成形炉の内部を排気しながら、炉内の真空度を１００Ｐａ以上２０００Ｐａ以下に保ちつつ加圧成形する。 At this time, by maintaining the temperature at 920 ° C. or more and 1050 ° C. or less in a vacuum of 100 Pa or more and 2000 Pa or less, the surface of the molding material is sublimated, and the surface is easily plastically deformed by introducing fine defects. Become. For this reason, the surface roughness of the ZnSe optical element after pressure molding is improved because the fine irregularities on the surface of the molding material are crushed during pressure molding, and the surface of the molding material follows the surface roughness of the upper and lower molds. To do. When the degree of vacuum is less than 100 Pa, the molding material is excessively sublimated, the weight reduction of the molding material cannot be ignored, and a desired optical element may not be obtained. On the other hand, when the degree of vacuum exceeds 2000 Pa, sublimation of the molding material surface and introduction of fine defects are insufficient, and the fine irregularities on the molding material surface cannot be crushed, and the surface of the molding material is up and down. Therefore, the surface roughness of the ZnSe optical element after pressure molding may increase. For this reason, pressure forming is performed while the degree of vacuum in the furnace is maintained at 100 Pa or more and 2000 Pa or less while exhausting the inside of the pressure forming furnace using a vacuum pump.

加圧成形の際に、１００Ｐａ以上２０００Ｐａ以下の真空中において、９２０℃以上１０５０℃以下の温度に保持することにより、ＣＶＤ法により合成したＺｎＳｅ多結晶体中に数ｐｐｍのオーダーで含有されていた不純物酸素を、１ｐｐｍ以下に減少させることができ、これに伴って、加圧成形後のＺｎＳｅ多結晶体の５３２ｎｍの波長の光の透過率を、４５％以上６５％以下に増大させることが可能になる。 During pressure forming, it was contained in the order of several ppm in the ZnSe polycrystal synthesized by the CVD method by maintaining the temperature at 920 ° C. or more and 1050 ° C. or less in a vacuum of 100 Pa or more and 2000 Pa or less. Impurity oxygen can be reduced to 1 ppm or less, and accordingly, the transmittance of light at a wavelength of 532 nm of the ZnSe polycrystalline body after pressure molding can be increased to 45% or more and 65% or less. become.

（実施例１）
搬送ガスとして純度９９．９９９％のアルゴンガスを用い、純度９９．９９９％のセレン化水素および純度９９．９９９％の溶融亜鉛からの亜鉛蒸気を、温度７００℃、雰囲気圧力７ｋＰａの反応炉内で反応させ、黒鉛基板上にＣＶＤ成長させてＺｎＳｅ多結晶体のバルクを合成した。前記バルクから密度測定用のサンプルを切り出し、アルキメデス法で絶対密度を測定した。前記絶対密度をＺｎＳｅの理論密度（５．２７ｇ／ｃｍ^３）で除することによって、相対密度を求めた結果、相対密度は９９．９％であった。 Example 1
Argon gas having a purity of 99.999% was used as a carrier gas, and zinc vapor from 99.999% pure hydrogen selenide and 99.999% pure molten zinc was introduced into a reactor having a temperature of 700 ° C. and an atmospheric pressure of 7 kPa. The bulk of ZnSe polycrystal was synthesized by reaction and CVD growth on the graphite substrate. A sample for density measurement was cut out from the bulk, and the absolute density was measured by Archimedes method. By dividing the absolute density by the theoretical density of ZnSe (5.27 g / cm ³ ), the relative density was determined. As a result, the relative density was 99.9%.

前記ＺｎＳｅ多結晶体のバルクから、直径１０．０ｍｍの円盤形状の成形素材を切り出し、前記成形素材の上下面を表面粗さＲａ０．０５μｍに両面研磨し、厚さ３．１ｍｍになるように仕上げた。成形素材と接触する面の表面粗さＲａを０．００３μｍとした上下押型の間に成形素材を挟んだ後、上下押型のそれぞれの外径と胴型の内径との直径差（クリアランス）が、１１００℃において０．００５ｍｍとなるように設計した胴型内に収納した。上下押型と胴型は共にグラッシーカーボン製のものを用いた。 A disk-shaped molding material having a diameter of 10.0 mm is cut out from the bulk of the ZnSe polycrystalline body, and the upper and lower surfaces of the molding material are both-side polished to a surface roughness Ra of 0.05 μm, and finished to a thickness of 3.1 mm. It was. After sandwiching the molding material between the upper and lower pressing dies having a surface roughness Ra of 0.003 μm on the surface in contact with the molding material, the difference in diameter (clearance) between the outer diameter of each of the upper and lower pressing dies and the inner diameter of the body die is It was housed in a barrel mold designed to be 0.005 mm at 1100 ° C. The upper and lower pressing molds and the body mold were both made of glassy carbon.

次に、不純物濃度が０．００１ｖｏｌ％以下かつ圧力が０．３気圧の窒素ガス雰囲気中において、前記上下押型を６３ＭＰａで加圧しながら１１００℃に１０分間保持して、前記成形素材を曲率１７０ｍｍの凸面と曲率１００ｍｍの凹面をもつ直径１０．０ｍｍ、中心厚３．０ｍｍのメニスカスレンズ形状の光学素子に変形させた。 Next, in a nitrogen gas atmosphere having an impurity concentration of 0.001 vol% or less and a pressure of 0.3 atm, the upper and lower pressing molds are held at 1100 ° C. for 10 minutes while pressing at 63 MPa, and the molding material has a curvature of 170 mm. The optical element was deformed into a meniscus lens-shaped optical element having a convex surface and a concave surface with a curvature of 100 mm and a diameter of 10.0 mm and a center thickness of 3.0 mm.

冷却後前記光学素子を成形型から取り出し、前記光学素子の光が透過する部分の凸面と凹面を表面粗さ計（Ｚｙｇｏ社製ＮｅｗＶｉｅｗ１００）を用いて測定した。その結果、凸面側中央部の表面粗さＲａは０．０１８１μｍ、凸面側端部の表面粗さＲａは０．０１３２μｍ、凹面側の表面粗さＲａは０．００９２μｍであった。また、分光光度計（日本分光社製Ｖ−６７０）を使って、反射防止コートをしない状態で波長５３２ｎｍの可視光に対する前記光学素子の透過率を測定した結果、６０．０％であった。 After cooling, the optical element was taken out from the mold, and the convex surface and concave surface of the optical element through which light was transmitted were measured using a surface roughness meter (New View 100, manufactured by Zygo). As a result, the surface roughness Ra of the convex surface side central portion was 0.0181 μm, the surface roughness Ra of the convex surface side end portion was 0.0132 μm, and the surface roughness Ra of the concave surface side was 0.0092 μm. Further, the transmittance of the optical element with respect to visible light having a wavelength of 532 nm was measured using a spectrophotometer (V-670 manufactured by JASCO Corporation) without an antireflection coating, and as a result, it was 60.0%.

（比較例１）
上下押型のそれぞれの外径と胴型の内径とのクリアランスが、１１００℃において０．０２０ｍｍとなるように設計した成形型を用いた以外は実施例１と同様にして、比較例１の光学素子を作製した。その結果、成形素材のＺｎＳｅが過度に昇華し、表面粗さおよび５３２ｎｍの可視光に対する透過率を測定することができなかった。 (Comparative Example 1)
Optical element of Comparative Example 1 in the same manner as in Example 1 except that a mold designed so that the clearance between the outer diameter of each of the upper and lower pressing molds and the inner diameter of the barrel mold is 0.020 mm at 1100 ° C. Was made. As a result, the molding material ZnSe was excessively sublimated, and the surface roughness and the transmittance for visible light of 532 nm could not be measured.

（実施例２）
実施例１と同様の方法で合成したＺｎＳｅ多結晶体のバルクから、直径１０．０ｍｍの円盤形状の成形素材を切り出し、厚さ３．０ｍｍになるように仕上げた。ＪＩＳ規格の１５０メッシュ（目開き１０９μｍ）の篩を用いて、ＺｎＳｅ多結晶体を粉砕した粉末を篩分することによって得た粒径１０９μｍ以下のＺｎＳｅ粉末を、前記成形素材の上面および下押型の上面にそれぞれ０．０２ｇずつ均一な厚みで散布した後、成形素材と接触する面の表面粗さＲａを０．００３μｍとした上下押型の間に成形素材を挟んで胴型内に収納した。このとき、上下押型のそれぞれの外径と胴型の内径とのクリアランスが、１０００℃において０．０２０ｍｍとなるように設計した成形型を用いた。上下押型と胴型は共にグラッシーカーボン製のものを用いた。 (Example 2)
A disk-shaped molding material having a diameter of 10.0 mm was cut out from the bulk of the ZnSe polycrystal synthesized by the same method as in Example 1, and finished to a thickness of 3.0 mm. Using a JIS standard 150 mesh (aperture 109 μm) sieve, a ZnSe powder having a particle size of 109 μm or less obtained by sieving the powder obtained by pulverizing the ZnSe polycrystal is obtained by using the upper surface of the molding material and the lower mold. After spraying 0.02 g each on the upper surface with a uniform thickness, the molding material was sandwiched between upper and lower molds having a surface roughness Ra of 0.003 μm on the surface in contact with the molding material, and housed in the body mold. At this time, a molding die designed so that the clearance between the outer diameter of each of the upper and lower pressing molds and the inner diameter of the barrel mold was 0.020 mm at 1000 ° C. was used. The upper and lower pressing molds and the body mold were both made of glassy carbon.

次に、不純物濃度が０．００１ｖｏｌ％以下かつ圧力が０．３気圧の窒素ガス雰囲気中において、前記上下押型を６３ＭＰａで加圧しながら１０００℃に１０分間保持して、前記成形素材を曲率１７０ｍｍの凸面と曲率１００ｍｍの凹面をもつ直径１０．０ｍｍ、中心厚３．０ｍｍのメニスカスレンズ形状の光学素子に変形させた。 Next, in a nitrogen gas atmosphere with an impurity concentration of 0.001 vol% or less and a pressure of 0.3 atm, the upper and lower pressing molds are held at 1000 ° C. for 10 minutes while pressing at 63 MPa, and the molding material has a curvature of 170 mm. The optical element was deformed into a meniscus lens-shaped optical element having a convex surface and a concave surface with a curvature of 100 mm and a diameter of 10.0 mm and a center thickness of 3.0 mm.

冷却後前記光学素子を成形型から取り出し、実施例１と同様にして前記光学素子の光が透過する部分の凸面と凹面の表面粗さ、および波長５３２ｎｍの可視光に対する前記光学素子の透過率を測定した。その結果、凸面側中央部の表面粗さＲａは０．０２８２μｍ、凸面側端部の表面粗さＲａは０．０２５４μｍ、凹面側の表面粗さＲａは０．００６５μｍであった。また、反射防止コートをしない状態における波長５３２ｎｍの可視光に対する前記光学素子の透過率は５０．４％であった。 After cooling, the optical element is taken out of the mold, and the surface roughness of the convex surface and concave surface of the optical element through which light is transmitted in the same manner as in Example 1, and the transmittance of the optical element with respect to visible light having a wavelength of 532 nm. It was measured. As a result, the surface roughness Ra of the central portion on the convex surface side was 0.0282 μm, the surface roughness Ra of the end portion on the convex surface side was 0.0254 μm, and the surface roughness Ra on the concave surface side was 0.0065 μm. Further, the transmittance of the optical element with respect to visible light having a wavelength of 532 nm in a state where no antireflection coating was applied was 50.4%.

（比較例２）
ＪＩＳ規格の１８メッシュ、線径０．４ｍｍ（目開き１．０１ｍｍ）の篩を用いて、ＺｎＳｅ多結晶体を粉砕した粉末を篩分することによって得た、粒径１．０１ｍｍ以下のＺｎＳｅ粉末を用いた以外は実施例２と同様にして、比較例２の光学素子を作製した。次に、実施例１と同様にして前記光学素子の光が透過する部分の凸面と凹面の表面粗さ、および波長５３２ｎｍの可視光に対する前記光学素子の透過率を測定した。その結果、凸面側中央部の表面粗さＲａは０．０８０９μｍ、凸面側端部の表面粗さＲａは０．１０４３μｍ、凹面側の表面粗さＲａは０．００５７μｍであった。また、反射防止コートをしない状態における波長５３２ｎｍの可視光に対する前記光学素子の透過率は４７．４％であった。 (Comparative Example 2)
ZnSe powder having a particle size of 1.01 mm or less obtained by sieving powder obtained by pulverizing ZnSe polycrystal using a JIS standard 18 mesh, wire diameter 0.4 mm (aperture 1.01 mm) sieve An optical element of Comparative Example 2 was produced in the same manner as Example 2 except that was used. Next, in the same manner as in Example 1, the surface roughness of the convex surface and the concave surface of the portion through which the light of the optical element transmits and the transmittance of the optical element with respect to visible light having a wavelength of 532 nm were measured. As a result, the surface roughness Ra of the central portion on the convex surface side was 0.0809 μm, the surface roughness Ra of the end portion on the convex surface side was 0.1043 μm, and the surface roughness Ra on the concave surface side was 0.0057 μm. Further, the transmittance of the optical element with respect to visible light having a wavelength of 532 nm in a state where no antireflection coating was applied was 47.4%.

（実施例３）
実施例１と同様の方法で合成したＺｎＳｅ多結晶体のバルクから、直径１０．０ｍｍの円盤形状の成形素材を切り出し、前記成形素材の上下面を表面粗さＲａ０．０５μｍに両面研磨し、厚さ３．１ｍｍになるように仕上げた。成形素材と接触する面の表面粗さＲａを０．００３μｍとした上下押型の間に成形素材を挟んで胴型内に収納した。このとき、上下押型のそれぞれの外径と胴型の内径とのクリアランスが、１０００℃において０．０２０ｍｍとなるように設計した成形型を用いた。上下押型と胴型は共にグラッシーカーボン製のものを用いた。 (Example 3)
A disc-shaped molding material having a diameter of 10.0 mm was cut out from the bulk of the ZnSe polycrystal synthesized by the same method as in Example 1, and the upper and lower surfaces of the molding material were both-side polished to a surface roughness Ra of 0.05 μm. Finished to 3.1 mm. The molding material was sandwiched between upper and lower pressing dies having a surface roughness Ra of 0.003 μm on the surface in contact with the molding material, and stored in the body mold. At this time, a molding die designed so that the clearance between the outer diameter of each of the upper and lower pressing molds and the inner diameter of the barrel mold was 0.020 mm at 1000 ° C. was used. The upper and lower pressing molds and the body mold were both made of glassy carbon.

次に、８００Ｐａの真空中において、前記上下押型を６３ＭＰａで加圧しながら１０００℃に１０分間保持して、前記成形素材を曲率１７０ｍｍの凸面と曲率１００ｍｍの凹面をもつ直径１０．０ｍｍ、中心厚３．０ｍｍのメニスカスレンズ形状の光学素子に変形させた。 Next, in a vacuum of 800 Pa, the upper and lower pressing molds are held at 1000 ° C. for 10 minutes while pressing at 63 MPa, and the molding material is 10.0 mm in diameter with a convex surface with a curvature of 170 mm and a concave surface with a curvature of 100 mm, and a center thickness of 3 It was transformed into an optical element having a meniscus lens shape of 0 mm.

冷却後前記光学素子を成形型から取り出し、実施例１と同様にして前記光学素子の光が透過する部分の凸面と凹面の表面粗さ、および波長５３２ｎｍの可視光に対する前記光学素子の透過率を測定した。その結果、凸面側中央部の表面粗さＲａは０．０１６７μｍ、凸面側端部の表面粗さＲａは０．０１２２μｍ、凹面側の表面粗さＲａは０．０１３９μｍであった。また、反射防止コートをしない状態における波長５３２ｎｍの可視光に対する前記光学素子の透過率は６０．１％であった。 After cooling, the optical element is taken out of the mold, and the surface roughness of the convex surface and concave surface of the optical element through which light is transmitted in the same manner as in Example 1, and the transmittance of the optical element with respect to visible light having a wavelength of 532 nm. It was measured. As a result, the surface roughness Ra of the central portion on the convex surface side was 0.0167 μm, the surface roughness Ra of the end portion on the convex surface side was 0.0122 μm, and the surface roughness Ra on the concave surface side was 0.0139 μm. Further, the transmittance of the optical element with respect to visible light having a wavelength of 532 nm in a state without an antireflection coating was 60.1%.

（実施例４）
成形素材を光学素子に変形させる際に、真空度を１２００Ｐａ、上下押型を加圧する圧力を５１ＭＰａとした他は実施例３と同様の方法により、実施例４の光学素子を作製した。次に、実施例１と同様にして前記光学素子の光が透過する部分の凸面と凹面の表面粗さ、および波長５３２ｎｍの可視光に対する前記光学素子の透過率を測定した。その結果、凸面側中央部の表面粗さＲａは０．０２３２μｍ、凸面側端部の表面粗さＲａは０．０１９３μｍ、凹面側の表面粗さＲａは０．００８９μｍであった。また、反射防止コートをしない状態における波長５３２ｎｍの可視光に対する前記光学素子の透過率は５９．８％であった。 Example 4
The optical element of Example 4 was produced in the same manner as in Example 3 except that when the molding material was deformed into an optical element, the degree of vacuum was 1200 Pa and the pressure for pressing the upper and lower pressing molds was 51 MPa. Next, in the same manner as in Example 1, the surface roughness of the convex surface and the concave surface of the portion through which the light of the optical element transmits and the transmittance of the optical element with respect to visible light having a wavelength of 532 nm were measured. As a result, the surface roughness Ra of the convex surface side central portion was 0.0232 μm, the surface roughness Ra of the convex surface side end portion was 0.0193 μm, and the surface roughness Ra of the concave surface side was 0.0089 μm. Further, the transmittance of the optical element with respect to visible light having a wavelength of 532 nm in a state where no antireflection coating was applied was 59.8%.

（実施例５）
成形素材を光学素子に変形させる際に、真空度を１２００Ｐａ、上下押型を加圧する圧力を４０ＭＰａとした他は実施例３と同様の方法により、実施例５の光学素子を作製した。次に、実施例１と同様にして前記光学素子の光が透過する部分の凸面と凹面の表面粗さ、および波長５３２ｎｍの可視光に対する前記光学素子の透過率を測定した。その結果、凸面側中央部の表面粗さＲａは０．０２０２μｍ、凸面側端部の表面粗さＲａは０．０２８９μｍ、凹面側の表面粗さＲａは０．０１３３μｍであった。また、反射防止コートをしない状態における波長５３２ｎｍの可視光に対する前記光学素子の透過率は５９．６％であった。 (Example 5)
The optical element of Example 5 was produced in the same manner as in Example 3 except that when the molding material was deformed into an optical element, the degree of vacuum was 1200 Pa and the pressure for pressing the upper and lower pressing molds was 40 MPa. Next, in the same manner as in Example 1, the surface roughness of the convex surface and the concave surface of the portion through which the light of the optical element transmits and the transmittance of the optical element with respect to visible light having a wavelength of 532 nm were measured. As a result, the surface roughness Ra of the convex surface side central portion was 0.0202 μm, the surface roughness Ra of the convex surface side end portion was 0.0289 μm, and the surface roughness Ra of the concave surface side was 0.0133 μm. Further, the transmittance of the optical element with respect to visible light having a wavelength of 532 nm in a state without an antireflection coating was 59.6%.

（比較例３）
成形素材を光学素子に変形させる際に、不純物濃度が０．００１ｖｏｌ％以下かつ圧力が０．３気圧の窒素ガス雰囲気中とした他は実施例３と同様の方法により、比較例３の光学素子を作製した。次に、実施例１と同様にして前記光学素子の光が透過する部分の凸面と凹面の表面粗さ、および波長５３２ｎｍの可視光に対する前記光学素子の透過率を測定した。その結果、凸面側中央部の表面粗さＲａは０．０３１９μｍ、凸面側端部の表面粗さＲａは０．０５０５μｍ、凹面側の表面粗さＲａは０．０１１７μｍであった。また、反射防止コートをしない状態における波長５３２ｎｍの可視光に対する前記光学素子の透過率は５５．４％であった。 (Comparative Example 3)
The optical element of Comparative Example 3 was manufactured in the same manner as in Example 3 except that the molding material was deformed into an optical element in a nitrogen gas atmosphere having an impurity concentration of 0.001 vol% or less and a pressure of 0.3 atm. Was made. Next, in the same manner as in Example 1, the surface roughness of the convex surface and the concave surface of the portion through which the light of the optical element transmits and the transmittance of the optical element with respect to visible light having a wavelength of 532 nm were measured. As a result, the surface roughness Ra of the convex side central part was 0.0319 μm, the surface roughness Ra of the convex side end part was 0.0505 μm, and the surface roughness Ra of the concave side was 0.0117 μm. Further, the transmittance of the optical element with respect to visible light having a wavelength of 532 nm in a state without an antireflection coating was 55.4%.

今回開示された実施形態および実施例はすべての点で例示であって制限的なものではない。本発明の技術的範囲は上記の説明ではなく特許請求の範囲によって示され、特許請求の範囲と均等の範囲でのすべての変更が含まれる。 The embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The technical scope of the present invention is shown not by the above description but by the scope of claims, and includes all modifications within the scope equivalent to the scope of claims.

本発明によるＺｎＳｅ多結晶体は、赤外線透過窓や赤外線レンズとして好ましく用いることができ、炭酸ガスレーザーの光学系に用いた場合は、光軸調整の際に波長５３２ｎｍの緑色レーザーを使用して、肉眼での光軸調整を可能にすることができる。 The ZnSe polycrystalline body according to the present invention can be preferably used as an infrared transmission window or an infrared lens, and when used in an optical system of a carbon dioxide gas laser, a green laser having a wavelength of 532 nm is used when adjusting the optical axis, The optical axis can be adjusted with the naked eye.

１上押型
２下押型
３胴型
４ＺｎＳｅ多結晶体（成形素材）
５ＺｎＳｅ多結晶体（光学素子）
６加圧力 1 Upper die 2 Lower die 3 Body die 4 ZnSe polycrystal (molding material)
5 ZnSe polycrystal (optical element)
6 Pressure

Claims

測定試料の厚み３ｍｍかつ反射防止コートをしない状態における波長５３２ｎｍの光の透過率が４５％以上６５％以下であり、
前記光が透過する部分の表面粗さＲａが０．０３μｍ以下である、
ＺｎＳｅ光学素子。 The transmittance of light having a wavelength of 532 nm in a state where the thickness of the measurement sample is 3 mm and the antireflection coating is not applied is 45% or more and 65% or less
The surface roughness Ra of the portion through which the light is transmitted is 0.03 μm or less.
ZnSe optical element.

前記光が透過する部分が機械加工されていない請求項１に記載のＺｎＳｅ光学素子。 The ZnSe optical element according to claim 1, wherein the light transmitting portion is not machined.

ＣＶＤ法によりＺｎＳｅ多結晶体を合成する工程と、
前記ＺｎＳｅ多結晶体と接触する面の表面粗さＲａを０．００８μｍ以下とした上下押型の間に前記ＺｎＳｅ多結晶体を挟んだ後、上下押型のそれぞれの外径と胴型の内径とのクリアランスが、前記ＺｎＳｅ多結晶体を加圧変形する温度において０．０１０ｍｍ以下となるように設計した胴型内に収納し、不純物濃度が０．００１ｖｏｌ％以下かつ圧力が０．１気圧以上１０気圧以下の非酸化性ガス雰囲気中において、前記上下押型を加圧しながら１０５０℃を超え１１５０℃以下の温度に保持して、前記胴型と前記上下押型で構成される形状に前記ＺｎＳｅ多結晶体を変形させる工程と、
を備えるＺｎＳｅ光学素子の製造方法。 A step of synthesizing a ZnSe polycrystal by a CVD method;
After sandwiching the ZnSe polycrystal body between the upper and lower pressing molds whose surface roughness Ra of the surface in contact with the ZnSe polycrystal body is 0.008 μm or less, the outer diameter of each of the upper and lower pressing molds and the inner diameter of the body mold The clearance is housed in a barrel mold designed to be 0.010 mm or less at the temperature at which the ZnSe polycrystal is pressure-deformed, the impurity concentration is 0.001 vol% or less, and the pressure is 0.1 to 10 atm. In the following non-oxidizing gas atmosphere, the upper and lower pressing molds are pressurized and held at a temperature exceeding 1050 ° C. and not higher than 1150 ° C. A step of deforming;
A method of manufacturing a ZnSe optical element.

ＣＶＤ法によりＺｎＳｅ多結晶体を合成する工程と、
前記ＺｎＳｅ多結晶体の上下押型と接触する面、および表面粗さＲａを０．００８μｍ以下とした上下押型の前記ＺｎＳｅ多結晶体と接触する面の少なくとも一方に、粒径１０９μｍ以下のＺｎＳｅ粉末を散布した後、前記ＺｎＳｅ多結晶体を上下押型で挟んで胴型内に収納し、不純物濃度が０．００１ｖｏｌ％以下かつ圧力が０．１気圧以上１０気圧以下の非酸化性ガス雰囲気中において、前記上下押型を加圧しながら９２０℃以上１０５０℃以下の温度に保持して、前記胴型と前記上下押型で構成される形状に前記ＺｎＳｅ多結晶体を変形させる工程と、
を備えるＺｎＳｅ光学素子の製造方法。 A step of synthesizing a ZnSe polycrystal by a CVD method;
ZnSe powder having a grain size of 109 μm or less is applied to at least one of the surface of the ZnSe polycrystal body that contacts the vertical pressing mold and the surface that contacts the vertical pressing mold with the surface roughness Ra of 0.008 μm or less. After spraying, the ZnSe polycrystalline body is sandwiched between upper and lower pressing molds and accommodated in a barrel mold, and in a non-oxidizing gas atmosphere having an impurity concentration of 0.001 vol% or less and a pressure of 0.1 atm or more and 10 atm or less, Maintaining the temperature at 920 ° C. or more and 1050 ° C. or less while pressurizing the upper and lower pressing molds, and deforming the ZnSe polycrystalline body into a shape constituted by the barrel mold and the upper and lower pressing molds;
A method of manufacturing a ZnSe optical element.

ＣＶＤ法によりＺｎＳｅ多結晶体を合成する工程と、
前記ＺｎＳｅ多結晶体と接触する面の表面粗さＲａを０．００８μｍ以下とした上下押型の間に前記ＺｎＳｅ多結晶体を挟んだ後、胴型内に収納し、１００Ｐａ以上２０００Ｐａ以下の真空中において、前記上下押型を加圧しながら９２０℃以上１０５０℃以下の温度に保持して、前記胴型と前記上下押型で構成される形状に前記ＺｎＳｅ多結晶体を変形させる工程と、
を備えるＺｎＳｅ光学素子の製造方法。 A step of synthesizing a ZnSe polycrystal by a CVD method;
The ZnSe polycrystal body is sandwiched between upper and lower pressing molds whose surface roughness Ra of the surface in contact with the ZnSe polycrystal body is 0.008 μm or less, and then accommodated in a body mold, and in a vacuum of 100 Pa or more and 2000 Pa or less. And holding the upper and lower pressing molds at a temperature of 920 ° C. or higher and 1050 ° C. or lower to deform the ZnSe polycrystalline body into a shape constituted by the body mold and the upper and lower pressing molds;
A method of manufacturing a ZnSe optical element.