Abbe's refractometer - Abbe's refractometer

...By replacing the 30° prism with one with a different refractive index, refractive indices between 1.3 and 1.6 can be measured with an accuracy of about 4 to 5 decimal places. Other refractometers that use total reflection include the Abbe refractometer, Pulfrich refractometer, and crystal refractometer. When measuring the refractive index of a solid sample, the polished surface of the sample is placed in close contact with the surface of a prism with a known refractive index via 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, and d is the thickness of the measurement medium, both of which are known) or the optical path difference ⊿ nd (⊿ n is the refractive index difference). ...

*Some of the terminology used to refer to "Abbe refractometer" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…30゜プリズムをいろいろな屈折率をもつものに交換することによって，1.3～1.6の屈折率を小数点以下4～5桁程度の精度で測定できる。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。…

※「アッベの屈折計」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