Computer-generated holograms for optical spatial filtering drawn by a laser scanner have several advantages, such as they could be obtained with the proper size directly without further reduction photographically, and the pixels of the hologram with grey scales. We design and. construct such a system but with some modifications to meet the requirements of using simple and inexpensive optics as well as obtainable electronics. A field lens is adapted to keep the scanning beams almost fixed during their entering into the camera lens and hence it is unable to use a camera lens of f-number down to less than f/l:2. The reduction ratio of the dimensions of the input aperture to the final pixel is chosen to be 1:32, the galvanometer-driven scanning mirror could cover the first sidelobes of the diffraction pattern of the input aperture. The system is driven by a compact CMOS electronics which is assembled in our laboratory, and used to control the scanning mirror and the acoustooptio shutter synchronously. The present setup has the following capabilities: (1) grey scale: 127; (2) spatial resolution; (3) size of the hologram in mm2; 10.2×10.2; (4)space-bandwidth product: 1024×512; (5) time needed in minutes: 17. We have also fabricated several spatial filters for optical processing by using this system and the performances of such filters are presented.