Abstract: ：A simple method to calculate the diffraction field of the transmission rectangle phase grating is proposed. The diffraction spectrum of the transmission phase grating is analyzed. It is shown that the diffraction field of the transmission phase grating is closely related to the grating＇ s optical thickness and the incident wavelength. A condition under which the diffraction energy will move from zero order to the first order diffraction spectrum is obtained. The discussion on the passable applications of the grating is made.

Key words: phase grating, diffraction spectrum, spectrometer, light deflector