Goniophotometer

Japanese: ゴニオフォトメーター（英語表記）goniophotometer

A device that measures the distribution of light intensity in each direction, i.e., light distribution, of objects that emit light or that diffusely transmit or reflect light, such as light sources, lighting fixtures, and lighting and optical materials. The receiver rotates on a circle or sphere centered on the object, always with the light receiving surface facing toward the center, and measures the light intensity. In the case of a transmitting (reflecting) object, a parallel beam of light is made to enter from a fixed direction, and the light distribution of the transmitted (reflected) light is measured. There are also devices that rotate a reflector instead of rotating the receiver, and measure the reflected light.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

光源，照明器具，照明用･光学用材料など，光を発したり，光を拡散透過または拡散反射する物体の，各方向への光の強度の分布，すなわち配光を測定する装置。受光器がその物体を中心とする円周上または球面上を，つねに受光面を中心方向に向けながら回転し，光の強度を測定する。透過(反射)物体の場合には光を平行ビームにして一定方向から入射させ，その透過(反射)光の配光を測定する。受光器を回転させる代りに反射鏡を回転させ，その反射光を測定する装置もある。

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

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