Optical filter with one-dimensional density distribution produced by a laser diode Available to Purchase

A system for making patterns on a photographic film is newly developed, which is used for producing optical filters with one-dimensional density distribution. The system consists of a laser diode LD for exposure light source and a cylindrical lens for transforming a elliptical profile of a laser beam intensity into a linear profile. The principle of this system is to modulate the laser beam intensity according to the filter pattern density. In arranging the system, diffraction patterns which depend on numerical aperture of collimator are estimated and the most suitable focusing position of the LD beam is determined experimentally for obtaining a uniform power density distribution on the focus position of the cylindrical lens. The system is operated with a micro-processor with an 8 bit D/A converter, which can produce patterns of 256 level gradation density. Periodical sinusoidal pattern and functional pattern for optical range meter which does not use position sensitive device PSD are produced. Errors in the transmittance of the filter patterns are less than 10 %.