Optical system transmittance detection base on the cross-correlation technique

The optical system transmittance is the ratio of optical instrument emergent light flux with incident light flux, and embodies the ability that transmitting light radiant energy of an optical instrument. It is an important performance index in optical system, especially in the telescopic optical system. In order to decrease the effect of the backlight, the traditional single channel detection method must be achieved in the darkroom. But it can not avoid the interference of 1/f noise and the illuminant wave because the detected signal is direct current signal, and the detecting accuracy is low. The paper proposes an optical transmittance detecting method with double beams and double frequencies based on the correlation detection technology. The method avoid the influences of 1/f, background light and illuminant wave effectively because of adopting the correlation detecting technology, and it not only can achieve the detecting in the bright field, but also improves the detecting accuracy finer than 1%, and could replace the single channel detection method that adopted at present.