Abstract: Light irradiated to a sample is detected by a detector in order to measure the optical properties of the sample. The image of a minute virtual light source for the light is focused in the neighborhood of the measuring face of the sample by a first optical system arranged between the light source and the sample. The light outgoing from the sample is incident to the detector by way of a second optical system arranged between the sample and the detector and having conjugate points in the neighborhood of the measuring face of the sample and of the light receiving point of the detector.

Abstract: A photoelastic effect measuring device comprising a single white light source, a prism dispersing light emitted by said white light source and a variable slit device, which selects an arbitrary spectrum of light thus dispersed is disclosed, in which for a photoelastic effect measurement using white light, the slit width is opened totally so that all the light spectrum pass therethrough so as to pass through a sample to be measured and for a photoelastic effect measurement using a specified monochromatic light beam, the slit width is controlled so as to have a predetermined opening so that only a specified light spectrum can pass therethrough so as to pass through a sample to be measured.

Abstract: In a spectrophotometer including a housing, an optical system mounted in the housing and a specimen chamber formed by partitioning a part of the housing for mounting therein a sample cell, the specimen chamber is formed with an opening through which the sample cell is mounted and dismounted and a cover plate is mounted so as to be slidably movable between a closing position where the opening of the chamber is wholly covered by the cover plate and an opening position where the specimen chamber is accessible from outside of the housing.