Abstract: By combining with acousto-optic effect and Bragg diffraction of the monochromatic wave，the quantitative

relation between wavelength of the acoustic wave and the wavelength of the monochromatic wave are deduced.

Then the unknown monochromatic wavelength is measured by adjusting the acoustic frequency. The scheme is based

on Bragg diffraction as the theoretical basis. In contrast to different technologies，we use acousto-optic devices with

the most stable and large acousto-optic factor，and solved the environmental factors on the impact of such experiments

is too large，cumbersome experimental steps and other issues successful. This program can directly adjust the

acoustic frequency to achieve a variety of monochromatic wavelength measurement，and wide the measurement range

of the wavelength of monochromatic.

Key words: acousto-optic effect, Bragg diffraction, monochromatic wavelength