JPS58198007A - Diffraction grating having protective film - Google Patents

Abstract

PURPOSE:To obtain a diffraction grating having a protective film, light in weight and causing no defect, by uniformly coating the surface of the diffractive grating obtd. by forming a wavy relief on the surface of a light-transmitting resin, with a transparent material having a refractive index similar to said resin in such a thickness to keep that relief form. CONSTITUTION:A relief diffraction grating 2 made of light-transmitting resin having uniform refractive index is formed on a transparent flat glass plate base 1 or the like. The diffraction grating is obtained efficiently by forming interference fringes on a photoresist especially by the holographic technique. A protective film 14 made of transparent material having refractive index near that of the used resin is formed on the surface of the diffractive grating 2 in a uniform thickness so as to keep this relief form. For example, when the photoresist having 1.6-1.7 refractive index is used, polymono-chloroparaxylene having 1.64 refractive index is vapor deposited. SiO2 may be vapor deposited in accordance with refractive index of the grating 2. A light and uniform protective film 14 is thus formed, and trouble of crushing the relief face or causing stress strain is prevented.

Description

【発明の詳細な説明】 この発明はレリーフ（ロ）折格子において、その表面レ
リーフの形状を保護するための均一な保護膜を有する回
折格子に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a relief (b) diffraction grating having a uniform protective film for protecting the shape of its surface relief.

均一な屈折率を有する透明媒實が場所により厚さを変え
、その茨直にレリーフ状の凹凸が作られているｌ回折格
子け、表面レリーフ回折格子と呼ばれる。糠にホトレジ
ストに干渉縞を記録して作られる１回折格子は、正弦波
状の凹凸を有し、入射光に対する１」折効率も高く、ポ
ログラムスキャナー等として利用される。A diffraction grating in which the thickness of a transparent medium with a uniform refractive index varies depending on the location and relief-like irregularities are created along the thorns is called a surface relief diffraction grating. A single-diffraction grating made by recording interference fringes on a photoresist of rice bran has sinusoidal irregularities, has a high 1" refraction efficiency for incident light, and is used as a porogram scanner.

このようなレリーフ回υず格子の衣（栢レリーフの形状
を保護するた、め、子板ガラヌ會載斬接着するガラスシ
ール法がある。すなわち、第１図に示すように、表面に
レリーフ１ｌＩｉ２を有する基板ｌ上に保躾用ガラス３
を載１ｉｆｔ　Ｌ、周辺を接着剤４によってシールする
方法である。し７かし、この方法は、１呆謹用ガラス３
を接着する際に生ずる６カ歪みにより回折格子表面のレ
リーフ２がつぶれる欠点があり、呼だ、接着に部用する
接着剤４から発生するガスにより、回折格子戎面のレリ
ーフ２が破壊さね、る欠点も生じる口また接着なども手
間がかかり、回折格子としての゛直置も耐くなるという
問題もあった。In order to protect the shape of the relief grating (heather relief), there is a glass sealing method in which the relief grating is glued onto the surface of the relief grating. Maintenance glass 3 is placed on the substrate l having
This is a method of mounting 1ift L and sealing the periphery with adhesive 4. However, this method requires 1.
There is a drawback that the relief 2 on the surface of the diffraction grating is crushed due to the distortion that occurs when bonding the grating, and the relief 2 on the surface of the diffraction grating may be destroyed by the gas generated from the adhesive 4 used for bonding. However, there were also problems in that it took a lot of effort to bond, and it also became difficult to stand up directly as a diffraction grating.

この発明け、レリーフ２上に１．９１折格子材料とほぼ
同じ屈νｆ率の１呆謹１良を設けることにより、上記の
欠点のないレリーフのｖＩＡｔａ層を有する回折格子會
１８ようとするものである。This invention aims to provide a diffraction grating 18 having a vIAta layer of relief without the above-mentioned drawbacks by providing on the relief 2 a 1.91 grating material with a refractive νf almost the same as that of the 1.91 refraction grating material. It is.

以下、図面を参照（７て詳細に説明する。A detailed description will be given below with reference to the drawings.

第２図は６明平板カラスｌ上に４与が正弦波伏に変化し
た透光匪叫脂層２が形成されたレリ・−フ（ロ）折格子
ケ示す。このような透過型レリーフＩＱＩ折格子はホロ
グラフィック技術により製作されるが、そのための光学
系４第３図に示す。FIG. 2 shows a relief grating in which a translucent grating layer 2 with a sinusoidal wave pattern is formed on a 6-inch flat glass l. Such a transmission type relief IQI fold grating is manufactured by holographic technology, and an optical system 4 therefor is shown in FIG. 3.

レーザ光源５からの光分レンズ６で下行光とし、対物レ
ンズ７でピンホール８　ＶＣ集束する。ピンホール８を
通過した発散光はレンズ９により再び下行光となる。こ
の下行光はピンホール８のフィルタリング効呆によりほ
ぼガウス分布状の強虻分布を儒゛する。分布補正蒸着フ
ィルタ１゜け逆ガウス分布の透過率を持ち、ガウス強変
分布ケ有する下行光が透過すると一様分布の下行光とな
る。この一様分布の下行光はビームスプリッタ１１で２
つの光Ｗ、に分割され、１′）け反射＠１２で他方は反
射＠１３で反射され、共にガラス基板１上に塗布された
ホトレジスト２上に菫なり合うように照射される。この
ようにすれば、ホトレジスト２上でけ２つの光束は干渉
し、ψ１暗の縞を形成し、ホトレジスト２はこの明暗の
縞に応じて感光する。ホトレジストとしてポジタイプの
ものを用いた場合は、光照射後、現１埃処哩を行なえば
感光したＩＷ分／バ除去され、第２図のような正弦技法
のレリーフが形成される。The light from the laser light source 5 is split into downward light by a lens 6, and focused by an objective lens 7 through a pinhole 8VC. The diverging light that has passed through the pinhole 8 becomes downward light again by the lens 9. This descending light has a nearly Gaussian distribution due to the filtering effect of the pinhole 8. The 1° distribution correction vapor deposited filter has a transmittance of an inverse Gaussian distribution, and when downward light having a strong Gaussian distribution passes through it, it becomes downward light of a uniform distribution. This uniformly distributed downward light is split into two parts by the beam splitter 11.
The light W is split into two lights W, one of which is reflected by 1') and the other by reflection @13, and both of them are irradiated onto the photoresist 2 coated on the glass substrate 1 so as to overlap each other. In this way, the two light beams interfere on the photoresist 2, forming ψ1 dark stripes, and the photoresist 2 is exposed to light according to the bright and dark stripes. When a positive type photoresist is used, after light irradiation, dust treatment is performed to remove the exposed IW and form a sinusoidal relief as shown in FIG.

この発明においては、第４図に示すように、保護用ガラ
スの代りに透明固体被膜１４によって回折格子２の表１
ｔｉ］會被覆している。In this invention, as shown in FIG.
ti] is covered.

この固体被膜として要求される粂汗は透明体であること
、その屈折率はホトレジストの屈折率と同程変であるこ
と、保護膜として気密囲（ですぐれ、ある程度の強度を
持つことである。As a solid film, the film is required to be transparent, its refractive index to be as variable as the refractive index of photoresist, to be airtight as a protective film, and to have a certain degree of strength.

この粂１４：を満す材料として高分子物質、５ｉ０２７
などがある。Ｊｆｌを在市販のホトレジストの屈折率け
１６〜１７捏度であり、これにより製作されたレリーフ
回折格子に好適な保護膜材料の１し０をあげろと、屈折
率約１，６４のポリモノクロバラキシレンを・あけるこ
とが出来る。この高分子吻′−は蒸着法によって破膜を
形成することかで　　　・１きる。その１嘆阜が１回折
格子の溝の深さｈ以下であれば１回折格子の凹凸の形状
け（呆存出来る。A polymer substance, 5i027, is used as a material that satisfies this kettle 14:
and so on. Jfl has a refractive index of 16 to 17 degrees lower than that of commercially available photoresists, and a polymonochromatic material with a refractive index of about 1.64 was used to improve the protective film material suitable for relief diffraction gratings manufactured using this material. Can open xylene. This polymer proboscis can be formed by forming a membrane rupture using the vapor deposition method. If the depth of one groove is less than the depth h of the groove of one diffraction grating, the shape of the unevenness of one diffraction grating can be changed.

回折格子の材料が異なり、その屈折率が変った場合は、
当然、固体被膜の材料の屈折率もそれに近（八ものを選
ば斥ければなら々い。比較的屈折率の低いＩＯＩ折格子
材料に対しては、屈折率が１４６の５１０２　　を便う
ことが出来、これも蒸着法によパ］て被膜を作ることが
出来る。If the material of the diffraction grating is different and its refractive index changes,
Naturally, the refractive index of the solid coating material is close to that (one must be selected).For IOI grating materials with a relatively low refractive index, 5102 with a refractive index of 146 can be used. It is possible to form a film using the vapor deposition method.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は公知のガラスシール（′！″！１折格子の断面
図、第２図はレリーフ回折格子の断面図、第３図１しそ
の製作用光学系の光路図、第４図はこの発明の保朦被膜
ケ有するレリーフ回折格子の断面図 １：基板　２：ホトレジスト・レリーフ層３：保護ガラ
ス　４：接着剤　５：レーザ光源８：ピンホール　ｌＯ
：逆ガウス分布袖正フィルタ　ｌｌ：ビームスグリツタ
　１４：蒸着固体保護膜 特許出顧へ　　株式会社　リコー 出鵬人代理人　弁理士　佐　　藤　　文　　男（ほか１
名）Figure 1 is a cross-sectional view of a known glass seal ('!''!1 diffraction grating, Figure 2 is a cross-sectional view of a relief diffraction grating, Figure 3 is an optical path diagram of the optical system for its production, and Figure 4 is a cross-sectional view of this grating. Cross-sectional view of a relief diffraction grating with a protective coating according to the invention 1: Substrate 2: Photoresist relief layer 3: Protective glass 4: Adhesive 5: Laser light source 8: Pinhole lO
: Inverse Gaussian distribution sleeve positive filter ll: Beam sinter 14: Vapor-deposited solid protective film patent sponsorship Ricoh Co., Ltd. Patent attorney Fumi Sato (and 1 others)
given name)

Claims (1)

【特許請求の範囲】[Claims] 均一な屈折率の透光ケ四脂が、周期的に厚さが変化し、
ているレリーフ回折格子の表面に、上記透光１生働脂と
同程度の屈折率を持つ透明体により、表面レリーフの形
状を医存する程度の４与の均一な被覆を設けたことを特
徴とするレリーフ回折格子Translucent resin with a uniform refractive index changes thickness periodically,
The surface of the relief diffraction grating is coated with a transparent material having a refractive index similar to that of the above-mentioned translucent 1 living fat, and is coated uniformly to the extent that the shape of the surface relief is preserved. relief grating