Laser lithography is one of the main methods for manufacturing micro-optical and the binary optical masks. The smallest linewidth produced by laser lithography plays an important role in the properties of the micro-optical elements. The collimated laser beam (He-Cd laser λ=442 nm) was focused on the photoresist for exposure and light intensity distribution in the photoresist was derived out on the approximate assumption. One of its main properties, namely lithography resolution, was analyzed based on the light intensity distribution in the photoresist. When the incident beam is modulated by the amplitude elements or the phase elements, the light intensity distribution in the photoresist will be changed, and therefore the quality of the exposure line will be affected. The results of the calculations showed: normally, 1.0 μm linewidth on photresist can be achieved, when the central circle of the incident beam is obstructed, a super resolution linewidth of 0.6 μm can be achieved for the lithography lens, microscope objects (NA=0.65, 40x). However, it requires a more rigorous exposure energy control. The experimental exposure results on the laser direct writing system showed good agreements with the theoretical calculation.