Laser beam precision control in ultro-precision manufacturing or other applications is to manipulate the beam pointing, intensity distribution, shape, far field patterns and so on. The method of beam control we used is different from traditional way that with mechanical inertia parts. The Liquid Crystal Spacial Light Modulator (LCSLM) is an electronic controlled, programmable diffractive device, which is able to modulate the phase of incident beam, therefore generate the objective patterns in far field. To establish the relationship between phase distribution of LCSLM and the far field objective function that represents the requirement of application, FFT and improved G-S algorithm are employed. Multi-beam focal point 3D control, beam shaping from Gaussian distribution to square and annular distribution with flat-top are discussed. They were studied in both theoretical and experimental ways. The results are evaluated by using error of root mean square and diffraction efficiency, which are less than 1% and higher than 90%, respectively.
Visualization of sound field with uniform phase distribution using laser beam microphone coupled with computerized tomography method