Transmittance detection method for optical instrument in the bright field

The transmittance detecting method for optical instrument is researched in this paper. The optical transmittance for instrument is ratio of emergent light flux to incident light flux and embodies the transmittance capability of optical instrument. At present optical transmittance is widely detected by a single channel method, which must be finished in the darkroom in order to ensure detecting accuracy. To solve above problem, a novel detecting method is proposed based on principle of crosscorrelation. Imaging acquisition and processing card for accomplishing correlation operation is specially developed. The detecting system of transmittance is designed with double channels and double frequencies. Transmittance image is obtained, then processed by adopting Otsu image binary and morphological erode-dilate operation. It is proved from experiments that the accuracy of transmittance can reach 0.4% and the transmittance detecting method on cross-correlation eliminates effectively the background noise and improves the detecting accuracy, as to accomplish the detecting in the bright field, which could replace the single channel optical system adopted at present.