Optical detector employing an optically-addressed spatial light modulator

摘要

In an optical detector, a light source irradiates coherent light onto an objective. A Fourier transform lens receives the light diffracted and scattered at the objective and Fourier transforms the light to generate a Fourier image, the Fourier image having a high intensity spectral component corresponding to the periodic pattern on the objective and a low intensity spectral component corresponding to the abnormal portion. In an optically-addressed spatial light modulator, each of the optically-addressing part and the light modulating part receives the Fourier image at the corresponding portions. A threshold driving controller controls the spatial light modulator in its threshold operation so as to change a state in the light modulating part at a region where the high intensity spectral component of the Fourier image is incident while preventing the state from being changed in the light modulating part at a region where the low intensity spectral component of the Fourier image is incident, the changed state in the light modulating part modulating the high intensity spectral component of the Fourier image incident in the light modulating part. Thus, the modulated high intensity spectral component is separated from the unmodulated low intensity spectral component.