The AOM-100-1 is Used to Control the Power of Femtosecond Lasers within bh TCSPC Systems.
The bh TCSPC Handbook
10th edition, September 2023
The principle of an Acousto-Optical Modulator is shown in the figure below.
An acoustic wave is excited in the AOM crystal electrically by a high-frequency RF signal. The wave acts like a grating, and diffracts away a part of the laser light. The amount of diffracted light depends on the amplitude of the high-frequency signal. The angle at which the light is diffracted depends on the frequency and on the wavelength of the light. To maintain a constant diffraction angle the frequency of the electrical signal must be adjusted to the wavelength to maintain a constant angle of the output beam. The AOM control software therefore interacts with the wavelength control software for the Ti:Sa laser. For each wavelength selected in the laser control it automatically selects the appropriate frequency of the RF signal.