Liquid prism.

摘要

A liquid prism is disclosed. It includes a liquid in order to obtain a free liquid surface which is perpendicular to the direction of gravity, and a liquid container for sealing the liquid in it. At least a part of the bottom surface portion of the container is formed of a light transmitting material. A good thermal conductive material such as a metallic material is provided deep enough under the free liquid surface of the liquid so that the free liquid surface will not interfere with the free liquid surface, even when the container is inclined at angles within the range of measurement. At least a part of the good thermal conductive material is formed with an opening to permit the light from the bottom surface portion of the liquid container to transmit therethrough. The good thermal conductive material may be formed with an irregular portion.