Investigation of coherence properties of white light emission of tungsten lamp additionally excited with laser radiation

The coherence properties of white light emission of a tungsten incandescent lamp additionally excited with laser radiation are investigated. The degree of spatial coherence is determined from measurements of the contrast of interference fringe patterns obtained for a tungsten bulb as the light source. It is demonstrated that the degree of spatial coherence of an incandescent lamp is increased by additional excitation of the filament with focused laser radiation. Furthermore, the degree of spatial coherence can be adjusted by selecting the voltage applied to the filament. Such light sources can find applications in imaging techniques where precise control of spatial coherence of illumination is required.