報告書番号

T51

タイトル（和文）

デフォーマブルミラーを用いたレーザー光空間強度分布制御に関する研究

タイトル（英文）

The Comprehensive Research on the Laser Beam Intensity Profile Control using Deformable Mirror

概要 （図表や脚注は「報告書全文」に掲載しております）

原子レーザー法同位体分離におけるレーザー光の照射技術の向上を目的として、レーザー光の強度分布を制御できる新しい照射技術の開発を行った。（１）光学的座標変換の原理に基づく、デフォーマブルミラーを用いた新しいレーザー光の強度分布制御方式を提案した。（２）ミラーの表面形状の設計手法として、フレネル エラーリダクションアルゴリズムを開発した。この計算精度は約１λである。（３）９つの駆動素子を有するデフォーマブルミラーとＣＣＤカメラ、画像処理装置から構成されるレーザー光強度分布制御システムを開発した。（４）複雑形状の加工ミラーを用いてガウス分布のレーザー光を四角形均一強度分布のビームへ変換することができた。さらに、この加工ミラーを利用した光学的座標変換型レーザー共振器を提案した。

概要 （英文）

In atomic vapor laser isotope separation, laser irradiation methods are very important for improvement of the laser energy utilization efficiency, and hence for the improvement economic characteristics. Although only the compensation of distorted wave front using deformable mirror was developed, the new technology is necessary for higher irradiation efficiency. Therefore, we have proposed a new irradiation method which can control laser beam intensity profile using deformable mirrors. We have developed a laser beam intensity profile control device. Main results are as follows.(1) We proposed a laser beam intensity profile control method using deformable mirrors. This method is on the basis of the optical coordinate-transformation.The laser beam intensity profile can be changed by modifying phase profiles and Fresnel transformation. We clarified the feasibility of this method through the simulation of laser beam propagation and glass plate deformation.(2) We developed a Fresnel error reduction algorithm for mirror surface shape designing. Its precision is about 1λ.(3) We developed a laser beam intensity profile control system consists of a deformable mirror with mine actuators, a CCD camera, an image processor and a computer. It is very difficult to construct a control algorithm because calculations of mirror surfaces for intensity profile transformation are equivalent to phase retrieval problem.We avoided this problem using the Genetic Algorithm, and could control laser beam intensity profile automatically at the first time.(4) We developed a fabricated mirror with complicated surface profile. The laser beam was successfully transformed from Gaussian to rectangular uniform profile using this mirror. However, we also find that the small fabrication error of 10 nm causes transformation error. This fabricated optics will become a low cost optical element for intensity profile transformation.Moreover, we proposed an optical coordinate-transformation laser cavity using fabricated optics.

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