Development of micro-ellipsometer for precise measurement of refractive index, and its application to tephrochronology

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K12805
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Cultural assets study and museology
• Research Institution: Yamagata University
• Principal Investigator: Tsuru Toshihide 山形大学, 地域教育文化学部, 教授 (30306526)
• Research Collaborator: YAGI Hiroshi
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 偏光解析 / 屈折率計測 / テフラ

Outline of Final Research Achievements

In order to optically directly measure the refractive index of a tephra sample with a size of several hundred μm, a microscopic ellipsometer combining a Schwarzschild objective and a null ellipsometer was successfully fabricated. It was confirmed that the objective has a long working distance and a sufficient spatial resolution in observation. The good extinction condition in 4-zone measurements was achieved, and the null setting could be accurately determined. By using two reference samples of known optical constants, new analysis method for evaluating the polarization characteristics of the optical path in the apparatus was devised.

Free Research Field

応用光学

Academic Significance and Societal Importance of the Research Achievements

フォトニック結晶や液晶素子を始めとして偏光を利用した機能性素子の新規開発が進んでおり、微小領域の精密偏光計測の要求は高いが、いまだ偏光顕微鏡の域を出ないのが現状である。顕微鏡と偏光解析を融合した革新的なハイブリッド顕微鏡によって、顕鏡者の能力差などヒューマンエラー、水和や温度ムラの影響を排除した屈折率の直接計測が実現する。また、テフラの計測に限らず生体応用、表面・界面、固・液界面の計測など、従来法では計測困難な研究分野にも応用でき、学術研究に留まらない広範囲な産業分野への応用が期待できる。