The property of the computer programmable optical devices is investigated. The programmable lenses have been performed by operating an electrically addressable liquid crystal spatial light modulator (LC-SLM) in amplitude mode, binary phase mode, and continuous phase mode. The programmable lenslet arrays have also been carried out experimentally. Both the experimental and calculating results show that the continuous phase mode provides the best results in terms of both light efficiency and focus quality. The advantage of the programmable lenslet array over the conventional one is that each lenslet in the array can be controlled individually. An 8×8 array mode without the central 4×4 light spot array generator has been demonstrated experimentally. The programmable lens was also implemented as a convenient way of investigating the aberration of the lenses experimentally. Although the computer programmable LC-SLM device has its great flexibility, its finite pixel size limits its fineness and, therefore, limits its applications.