Laser-diode collimating light sources using micro-Fresnel lenses

Compact and low-cost laser-diode collimating light sources that employ a thin and mass-producible diffractive micro-Fresnel lens have been developed for optical information-processing equipment such as laser-beam printers. For the compensation of the defocusing of an output beam caused by temperature dependence of the laser-diode wavelength, engineering plastics with different thermal expansion coefficients are adopted for the components. The fabricated light source emits stably up to 60°C. The present laser light sources exhibit allowable optical characteristics for optical information-processing equipment as well as cost-efficient mass production.