Interferometry

...Other refractometers that use total reflection include the Abbe refractometer, the Pulfrich refractometer, and the crystal refractometer. When measuring the refractive index of a solid sample, the polished surface of the sample is placed in contact with a prism surface with a known refractive index through a thin liquid layer, and the critical angle of total reflection is measured. Interference methods determine the refractive index by measuring the optical path length nd ( n is the refractive index, d is the thickness of the measurement medium, which is known) or the optical path difference ⊿ nd (⊿ n is the refractive index difference). Figure 3 shows an example of interference methods, the Jamin interference refractometer, in which parallel flat glass plates of the same thickness with silver plating on the back side are placed almost parallel to each other, and the light reflected from the front and back sides is divided into two beams, one of which is passed through a reference cell and the other through a sample cell, and the two beams are then brought together to interfere, and the interference fringes are observed with a telescope. ...

*Some of the terminology that refers to "interferometry" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…全反射法を用いる屈折計には，このほかにアッベの屈折計，プルフリヒの屈折計，結晶屈折計などがあり，固体試料の屈折率測定の場合は，試料の研磨した面を屈折率既知のプリズム面に薄い液層を介して密着させ，全反射の臨界角を測定する。　干渉法は光路長nd(nは屈折率，dは測定媒質の厚さで既知)，または光路差⊿nd(⊿nは屈折率差)の測定から屈折率を求めるものである。図3は干渉法の例であるジャマンの干渉屈折計を示したもので，裏面に銀めっきした同じ厚さの平行平面ガラス板をほぼ平行に置き，表面，裏面で反射する光を用い光線束を二つに分け，一方を基準セル，他方を試料セルに通した後，二つの光線束をいっしょにして干渉させ，干渉縞を望遠鏡で観測する。…

※「干渉法」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報