Wavefront Correction of Violet Laser Diode and Color Micro-marking on Plastic Surface

Abstract

The laser diode (LD) is a light source characterized by small size, light weight and high performance. Osaka University has been actively conducting research and development to precisely collect and directly process infrared LD light. Violet laser diode (VLD) light can be focused in a smaller spot because its wavelength is shorter than that of infrared LD light.
We report herein the development of a unit to precisely focus VLD light and the use of this unit, together with dyes and pigments, to create color micro-markings on a plastic plate. Concretely, we show corrections made to ensure that the single-mode VLD light can be changed to collimated light via a collimator lens and its wavefront aberration can be measured for precise light collection. The corrected light was precisely focused and used to irradiate a dye or pigment that was applied to a plastic surface. This resulted in markings on the part exposed to irradiation despite the fact that no absorption agent was used. We also achieved microscopic markings on a polyester (PET) plate by optimizing irradiation conditions, as well as 100-µm and 200-µm color markings.