JPS6212881B2 - - Google Patents
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- Publication number
- JPS6212881B2 JPS6212881B2 JP57064749A JP6474982A JPS6212881B2 JP S6212881 B2 JPS6212881 B2 JP S6212881B2 JP 57064749 A JP57064749 A JP 57064749A JP 6474982 A JP6474982 A JP 6474982A JP S6212881 B2 JPS6212881 B2 JP S6212881B2
- Authority
- JP
- Japan
- Prior art keywords
- film
- window
- transparent
- wavelength
- equation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- 230000001681 protective effect Effects 0.000 claims description 12
- 239000003513 alkali Substances 0.000 claims description 6
- 150000004820 halides Chemical class 0.000 claims description 6
- 239000005387 chalcogenide glass Substances 0.000 claims description 3
- MZQZQKZKTGRQCG-UHFFFAOYSA-J thorium tetrafluoride Chemical compound F[Th](F)(F)F MZQZQKZKTGRQCG-UHFFFAOYSA-J 0.000 claims description 3
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 claims 1
- 239000011521 glass Substances 0.000 claims 1
- 239000010408 film Substances 0.000 description 22
- 239000000758 substrate Substances 0.000 description 11
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 10
- 239000000463 material Substances 0.000 description 7
- 230000003287 optical effect Effects 0.000 description 7
- 229910002092 carbon dioxide Inorganic materials 0.000 description 5
- 239000001569 carbon dioxide Substances 0.000 description 5
- UKUVVAMSXXBMRX-UHFFFAOYSA-N 2,4,5-trithia-1,3-diarsabicyclo[1.1.1]pentane Chemical compound S1[As]2S[As]1S2 UKUVVAMSXXBMRX-UHFFFAOYSA-N 0.000 description 3
- 229940052288 arsenic trisulfide Drugs 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000011669 selenium Substances 0.000 description 2
- 229910004613 CdTe Inorganic materials 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- PXQJESZJGKEUJH-UHFFFAOYSA-N S=[Se](=S)=S Chemical compound S=[Se](=S)=S PXQJESZJGKEUJH-UHFFFAOYSA-N 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000012788 optical film Substances 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- SBIBMFFZSBJNJF-UHFFFAOYSA-N selenium;zinc Chemical compound [Se]=[Zn] SBIBMFFZSBJNJF-UHFFFAOYSA-N 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- PGAPATLGJSQQBU-UHFFFAOYSA-M thallium(i) bromide Chemical compound [Tl]Br PGAPATLGJSQQBU-UHFFFAOYSA-M 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000012780 transparent material Substances 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
- 239000002982 water resistant material Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/02—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of crystals, e.g. rock-salt, semi-conductors
Landscapes
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Surface Treatment Of Optical Elements (AREA)
- Lasers (AREA)
Description
【発明の詳細な説明】
本発明は耐水性の優れた保護膜を有し、アルカ
リハライドを基板としたブリユースター窓に関す
る。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Brewstar window having a protective film with excellent water resistance and having an alkali halide substrate.
従来、特に赤外線領域におけるブリユースター
窓の材料としては材料それ自身、耐水性が有り透
明な物質に限られた。例えばZnSe、GaAs、
CdTe、Ge、KRS−５等が挙げられるがそれぞれ
大きさや、透明な波長領域等に限りがあつたり、
光学歪が大きく高価であつたり又有毒性であつた
りして非常に使用条件が厳しいものであつた。一
方透明で光学歪が小さく、安価なアルカリハライ
ド（KCl、NaClなど）は潮解性があり湿度の多
い環境での長時間使用に耐えられないという欠点
を有していた。本発明はこれらの透明で光学歪が
小さく安価なアルカリハライドの様な材料の利点
を生かしかつ欠点である潮解性を透明で耐水性の
優れた保護膜を附することにより解決し、特に我
が国の様な多湿な状況下でかつ大パワーの炭酸ガ
スレーザ光に対しても使用出来る発生熱の少ない
ブリユースター窓を提供するものである。 Conventionally, materials for Brewster windows, particularly in the infrared region, have been limited to water-resistant and transparent materials. For example, ZnSe, GaAs,
Examples include CdTe, Ge, KRS-5, etc., but each has limitations in size, transparent wavelength range, etc.
It has a large optical distortion, is expensive, and is toxic, so its usage conditions are very strict. On the other hand, alkali halides (KCl, NaCl, etc.), which are transparent, have low optical distortion, and are inexpensive, have the disadvantage of being deliquescent and unable to withstand long-term use in humid environments. The present invention takes advantage of these materials such as transparent, low optical distortion, and inexpensive materials such as alkali halides, and solves the disadvantage of deliquescent properties by attaching a transparent and highly water-resistant protective film. To provide a Breustar window that generates little heat and can be used under various humid conditions and even with high power carbon dioxide laser light.
保護膜の材料としては水に溶けにくく、かつ透
明で、さらに薄膜状になつた時にピンホールの出
来にくいアモルフアス状態を示す三硫化ヒ素
As2S3、三硫化セレンAs2Se3等を代表とするカル
コゲナイドガラスや四弗化トリウム（ThF4）が挙
げられる。 As a material for the protective film, arsenic trisulfide is difficult to dissolve in water, is transparent, and exhibits an amorphous state that does not easily form pinholes when formed into a thin film.
Examples include chalcogenide glasses such as As 2 S 3 and selenium trisulfide As 2 Se 3 and thorium tetrafluoride (ThF 4 ).
屈折率ｎsなる基板はかならずＰ偏光の光に対
して反射率が零になる角度を一つもち、これを物
質固有のブリユースター角θBといい、屈折率ｎs
とθBとの間には一定の関係がある。 A substrate with a refractive index n s always has one angle at which the reflectance becomes zero for P-polarized light, and this is called the Brewster angle θ B unique to the material, and the refractive index n s
There is a certain relationship between and θ B.
θB＝tan-1（ｎs） ………(1)
さてこの様な基板の上に屈折率ｎFなる保護膜
を厚さｄFだけ附した場合、一般にはＰ偏光に対
する反射は零にならない。 θ B = tan -1 ( ns ) ......(1) Now, if a protective film with a refractive index n F and a thickness d F is attached to such a substrate, the reflection of P-polarized light will generally be zero. It won't happen.
波長と同じ程度の厚さの薄膜が屈折率ｎsの基
板上に着いている場合の反射率を求めるには、干
渉現象を考慮に入れなければいけない。従つて、
膜厚と光の波長との関係が問題になつてくる。膜
厚をｄF、膜の屈折率をｎF、基板と反対側の屈折
率をｎp（通常空気などでｎp＝１）とし、光の波
長をλとすると、この境界面での反射率は次の様
に求めることが出来る（今簡単のために垂直入射
を考える）。 To determine the reflectance when a thin film with a thickness similar to the wavelength is deposited on a substrate with a refractive index n s , interference phenomena must be taken into account. Therefore,
The relationship between film thickness and wavelength of light becomes an issue. When the film thickness is d F , the refractive index of the film is n F , the refractive index on the side opposite to the substrate is n p (normally n p = 1 in air, etc.), and the wavelength of light is λ, the reflection at this interface is The rate can be calculated as follows (for simplicity, consider normal incidence).
Ｒ＝γ１ ２＋γ２ ２＋２γ１・γ２ｃｏｓ（４πｎＦｄ
Ｆ／λ）／１＋γ１ ２・γ２ ２＋２γ１・γ２ｃｏｓ（
４πｎＦｄＦ／λ）……
…(2)
ここでｎFｄFは光学的膜厚で、４πｎFｄF／λ
は膜厚の往復の距離をラジアン単位で表わしたも
のである。γ１、γ２は振幅反射率で、γ１はｎ
pとｎFの境界；γ２はｎFとｎsの境界での振幅反
射率である。したがつて
γ１＝ｎＦ−ｎｐ／ｎＦ＋ｎｐ………(3
)
γ２＝ｎｓ−ｎＦ／ｎｓ＋ｎＦ………(4
)
の関係にある。R=γ 1 2 + γ 2 2 +2γ 1・γ 2 cos(4πn F d
F /λ)/1+γ 1 2・γ 2 2 +2γ 1・γ 2 cos(
4πn F d F /λ)…… …(2) Here, n F d F is the optical film thickness, and 4πn F d F /λ
is the round trip distance of the film thickness in radians. γ 1 and γ 2 are amplitude reflectances, and γ 1 is n
The boundary between p and n F ; γ 2 is the amplitude reflectance at the boundary between n F and n s . Therefore, γ 1 =n F −n p /n F +n p ………(3
) γ 2 = n s − n F /n s + n F ………(4
).
(2)式においてｎFｄF＝λ／２の条件を満足すると(2)
式は
Ｒ＝（γ１＋γ２）２／（１＋γ１γ２）
２………(5)
(5)式に(3)、(4)を代入すると
Ｒ＝〔ｎＳ−ｎｐ／ｎＳ＋ｎｐ〕２………
(6)
となり、これは正さに基板そのものの反射率を表
わし、膜が光学厚みｎFｄF＝λ／２の条件を満足する
と膜のない状態を示すことになる。 If the condition n F d F =λ/2 is satisfied in equation (2), equation (2) becomes R=(γ 1 + γ 2 ) 2 /(1+γ 1 γ 2 )
2 ………(5) Substituting (3) and (4) into equation (5), R=[n S −n p /n S +n p ] 2 ………
(6), which exactly represents the reflectance of the substrate itself, and when the film satisfies the condition of optical thickness n F d F =λ/2, it indicates a state where there is no film.
今まで考えて来たのは垂直入射の場合であるが
今度は入射角が基板のブリユースター角である場
合を考えることにする。屈折率ｎF、厚さｄFなる
保護膜が形成された基板に入射角θBで光が入射
すると光は屈折率θFとなり、屈折角θF、入射角
θB、屈折率ｎF、ｎpとの間にはスネルの関係式
が有する。 Up until now we have considered the case of normal incidence, but now we will consider the case where the angle of incidence is the Brewster angle of the substrate. When light is incident at an angle of incidence θ B on a substrate on which a protective film with a refractive index n F and a thickness d F is formed, the light has a refractive index θ F , an angle of refraction θ F , an angle of incidence θ B , a refractive index n F , Snell's relational expression exists between n p and n p .
ｓｉｎθＦ／ｓｉｎθＢ＝ｎｐ／ｎＦ…
……(7)
よつて
なる関係式が得られる。 sinθ F /sinθ B = n p /n F …
……(7) Yotsute The following relational expression is obtained.
一方(2)式に対応する入射角が垂直でない式にお
けるcosの項は、
cos〔４πｎＦｄＦｃｏｓθＦ／λ〕………(9)
となるので(9)式の値が１になるような膜厚を選べ
ば薄膜の影響は除去される。すなわち膜厚が
なる条件を満足すれば膜があつても膜のない状態
すなわち入射角θBでＰ偏光の反射率が零とな
り、ブリユースター窓となる。 On the other hand, the cos term in the equation where the angle of incidence is not perpendicular to equation (2) is cos[4πn F d F cosθ F /λ]...(9), so the value of equation (9) becomes 1. If such a film thickness is selected, the influence of the thin film will be removed. In other words, the film thickness is If the following conditions are satisfied, even if there is a film, the reflectance of P-polarized light becomes zero at an incident angle θ B , which means that there is no film, resulting in a Brewster window.
この様にして本発明は透明で光学歪が小さく、
安価なアルカリハライドの様な材料の利点を生か
し、かつ欠点である潮解性を保護膜を附すること
により解決したもので、特に我が国の様な多湿な
状況下でかつ大パワーの炭酸ガスレーザ光に対し
ても使用出来る発生熱の少ないブリユースター窓
を提供するものである。 In this way, the present invention is transparent and has low optical distortion.
It takes advantage of the advantages of inexpensive materials such as alkali halides, and solves the disadvantage of deliquescent properties by adding a protective film, making them particularly suitable for use in humid conditions like our country and with high-power carbon dioxide laser beams. To provide a brew star window that generates less heat and can also be used against other people.
実施例 １
炭酸ガスレーザ発振波長10.6μｍ用KCl基板を
使つた本発明によるブリユースター窓について説
明する。保護膜としては三硫化ヒ素As2S3を用
い、平行に仕上げられたKCl基板の両面に真空蒸
着法により附するものとする。蒸着すべき厚みは
式(10)を使い2.37μｍである。ここでλは10.6μ
ｍ、ｎFは2.38、θBは55.4゜を使つた。この様に
して作られた保護膜付ブリユースター窓を光軸に
対して55.4゜傾けておいた場合のＳ偏光とＰ偏光
に対する反射率の計算値を図に示す。図において
１はＳ偏光に対する反射率で、２はＰ偏光に対す
る反射率で、３は波長10.6μｍでＰ偏光に対する
反射率が零になりブリユースター窓として動作す
ることが示されている。Example 1 A Brewstar window according to the present invention using a KCl substrate for carbon dioxide laser oscillation wavelength of 10.6 μm will be described. Arsenic trisulfide (As 2 S 3 ) is used as the protective film, and it is applied to both sides of the parallel-finished KCl substrate by vacuum evaporation. The thickness to be deposited is 2.37 μm using equation (10). Here λ is 10.6μ
m, n F was 2.38, and θ B was 55.4°. The figure shows the calculated values of the reflectance for S-polarized light and P-polarized light when the Brewster window with a protective film made in this way is tilted at 55.4 degrees with respect to the optical axis. In the figure, 1 is the reflectance for S-polarized light, 2 is the reflectance for P-polarized light, and 3 is the reflectance for P-polarized light at a wavelength of 10.6 μm, which indicates that it operates as a Brewster window.
次に本発明のブリユースター窓に10KWという
大パワーの炭酸ガスレーザー光が入射したとした
時の中心点と周囲の冷却部との温度差を計算して
みる。ブリユースター窓は直径10cmで厚みが１cm
のKCl平行平板の両面に三硫化ヒ素As2S3が2.37
μｍづつ蒸着されている。このブリユースター窓
はその周辺で冷却されているものとする。計算を
簡単にするために、ブリユースター窓全面に一様
な強度分布のレーザ光が入射した場合の温度分布
を熱伝導方程式より計算すると結果は(11)式の様に
なる。 Next, let us calculate the temperature difference between the center point and the surrounding cooling section when a carbon dioxide laser beam with a high power of 10 KW is incident on the Brew Star window of the present invention. The Brewster window is 10cm in diameter and 1cm thick.
Arsenic trisulfide As 2 S 3 on both sides of KCl parallel plate is 2.37
It is deposited in μm increments. It is assumed that this brew star window is cooled around the area. To simplify the calculation, the temperature distribution when a laser beam with a uniform intensity distribution is incident on the entire surface of the Brewster window is calculated using the heat conduction equation, and the result is expressed as equation (11).
Ｔ−Ｔp＝（βＩ／４Ｋ）（Ｄ／２）２……
…(11)
ここでＴ（℃）は中心部での温度で、ＴO
（℃）は冷却されている周囲の温度で、β（cm
-1）はブリユースター窓の吸収係数であり、Ｄ
（cm）はブリユースター窓の直径、Ｋは熱伝導率
（Ｗ・cm-1・℃-1）Ｉはレーザ光強度（Ｗ・cm
-2）である。 T-T p = (βI/4K) (D/2) 2 ...
…(11) Here, T (℃) is the temperature at the center, T O
(℃) is the temperature of the surrounding area being cooled, β (cm
-1 ) is the absorption coefficient of the Brewster window, and D
(cm) is the diameter of the Brewstar window, K is the thermal conductivity (W cm -1 °C -1 ), I is the laser light intensity (W cm
-2 ).
ブリユースター窓の吸収係数βはKClの厚みｄ
にくらべ膜の厚みｄFが無視出来る時には(12)式で
求められる。 The absorption coefficient β of the Brewster window is the thickness d of KCl
In comparison, when the film thickness dF can be ignored, it can be found using equation (12).
β＝βAs2S3ｄＦ／ｄ＋βKCl＋βAs2S3ｄＦ／ｄ………(
12)
ここでβAs2S3≒１cm-1、βKCl≒１×10-4cm
-1dF＝2.37μｍ＝2.37×10-4cm-1、ｄ＝１cmの値
を代入すると、
β≒5.7×10-4cm-1 ………（13）
レーザ光強度Ｉは（14）式で求められる。β=βAs 2 S 3 d F /d+βKCl+βAs 2 S 3 d F /d……(
12) Here, βAs 2 S 3 ≒1cm -1 , βKCl≒1×10 -4 cm
-1 d F = 2.37 μm = 2.37 × 10 -4 cm -1 , and by substituting the value of d = 1 cm, β≒5.7 × 10 -4 cm -1 ...... (13) The laser light intensity I is (14) It is determined by the formula.
Ｉ＝10KW／π／４D2………（14）
Ｄ＝10cmを代入すると
Ｉ＝127W・cm-2 ………（15）
となる。(11)式にβ≒57×10-4cm-1、Ｉ≒127W・
cm-2、Ｋ＝0.065W・cm-1・℃-1の値を代入して、
中心部と周囲との温度差（Ｔ−To）を計算する
と、約７℃におさえることが出来、十分実用に耐
える。 I=10KW/π/4D 2 ......(14) Substituting D=10cm gives I=127W・cm -2 ......(15) In equation (11), β≒57×10 -4 cm -1 and I≒127W・
By substituting the values of cm -2 and K=0.065W・cm -1・℃ -1 ,
Calculating the temperature difference (T-To) between the center and the surrounding area, it can be kept to about 7 degrees Celsius, which is sufficient for practical use.
実施例 ２
KCl基板の両面に四弗化トリウム（ThF4）を蒸
着してなる保護膜付ブリユースター窓。ｎF＝
1.35、θB＝55.4゜、λ＝10.6μｍを使つて(10)式よ
り蒸着すべきThF4の厚みｄFは4.95μｍとなる。
実施例１と同様に55.4゜の入射角で入射して来る
Ｐ偏光に対する反射率は10.6μｍで零となりブリ
ユースター窓として動作する。Example 2 A Breustar window with a protective film formed by vapor depositing thorium tetrafluoride (ThF 4 ) on both sides of a KCl substrate. nF =
1.35, θ B = 55.4°, and λ = 10.6 μm, the thickness d F of ThF 4 to be deposited is 4.95 μm from equation (10).
As in Example 1, the reflectance for P-polarized light incident at an incident angle of 55.4° becomes zero at 10.6 μm, and it operates as a Brewstar window.
以上の実施例で示した様に本発明は、透明で光
学歪が小さく安価なKClの様なアルカリハライド
の材料の利点を生かし欠点である潮解性を、水に
溶けずアモルフアス状態の膜が得られるAs2S3、
As2Se2等のカルコゲナイドガラスやThF4等の保
護膜を附す事により解決したもので、10KWとい
う大パワーの炭酸ガスレーザ光にも使える安価な
ブリユースター窓が得られる利点を有する。 As shown in the examples above, the present invention takes advantage of the advantages of alkali halide materials such as KCl, which are transparent, have low optical distortion, and are inexpensive. As 2 S 3 ,
This problem was solved by attaching a protective film such as chalcogenide glass such as As 2 Se 2 or ThF 4 , and it has the advantage of providing an inexpensive Brewster window that can be used for carbon dioxide laser light with a high power of 10KW.
図はKClの平行平板の両面に保護膜として
As2S3を厚み2.37μｍ附したブリユースター窓の
入射角55.4゜に対する反射率の波長依存性を示す
図である。
The figure shows a protective film on both sides of a parallel plate of KCl.
FIG. 3 is a diagram showing the wavelength dependence of the reflectance of a Brewstar window with As 2 S 3 coated with a thickness of 2.37 μm at an incident angle of 55.4°.
Claims (1)
からなる平行平板の両面に膜厚（ｄF）が次式で
与えられ、赤外光に対して透明なカルコゲナイド
ガラスあるいは四弗化トリウムからなる保護膜を
設けたことを特徴とするブリユースター窓。 ここで、λは問題にしている波長、ｎFは波長
λにおける膜の屈折率、θBは平行平板に固有の
ブリユースター角である。[Claims] 1. The film thickness (d F ) on both sides of a parallel plate made of alkali halide that is transparent to infrared light is given by the following formula, and chalcogenide glass or tetragonal glass that is transparent to infrared light is given by the following formula. A brew star window characterized by having a protective film made of thorium fluoride. Here, λ is the wavelength in question, n F is the refractive index of the film at the wavelength λ, and θ B is the Brewster angle specific to parallel plates.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57064749A JPS58182602A (en) | 1982-04-20 | 1982-04-20 | Brewster window |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57064749A JPS58182602A (en) | 1982-04-20 | 1982-04-20 | Brewster window |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58182602A JPS58182602A (en) | 1983-10-25 |
| JPS6212881B2 true JPS6212881B2 (en) | 1987-03-23 |
Family
ID=13267116
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57064749A Granted JPS58182602A (en) | 1982-04-20 | 1982-04-20 | Brewster window |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58182602A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0797066B2 (en) * | 1985-10-22 | 1995-10-18 | 日本電信電話株式会社 | Transmission loss spectrum measuring device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3883214A (en) * | 1972-06-14 | 1975-05-13 | Westinghouse Electric Corp | Protective anti-reflective coatings for alkali-metal halide optical components |
| US4075885A (en) * | 1977-02-23 | 1978-02-28 | Iowa State University Research Foundation, Inc. | Rock borehole shear tester |
-
1982
- 1982-04-20 JP JP57064749A patent/JPS58182602A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3883214A (en) * | 1972-06-14 | 1975-05-13 | Westinghouse Electric Corp | Protective anti-reflective coatings for alkali-metal halide optical components |
| US4075885A (en) * | 1977-02-23 | 1978-02-28 | Iowa State University Research Foundation, Inc. | Rock borehole shear tester |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58182602A (en) | 1983-10-25 |
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