Versatile microscope-coupled high-intensity pulsed light source for high-speed cine photomicrography of microactuators

A compact high-intensity pulsed light source has been developed in order to match a microdynamic test facility for highspeed motion analysis of micromechanical components. The test stand encompasses a universal microscope Zeiss Axioplan, the new light source and an electronic ultra high-speed multiple framing camera Hadland Imacon 468. The light source consists of a narrow cylindrical Xe-filled discharge tube, thus providing a locally stable emission. Since the small-size flashlamp easily fits into a standard microscope lamphousing, it allows to maintain the advantages of Koehler illumination as well as switching to other types of lamphousings. The flash tube is operated via an artificial asymmetric transmission line and delivers a square light pulse with a flash duration of 110 mu s FWHM and a peak intensity of 50 Mcd. The light source illuminates the object uniformly within the interesting time window; image shuttering is provided in the camera by gated micro-channel-plate intensifiers. To test the efficiency of the total system for various standard visualization methods (transmitted light, reflected light and differential interference contrast), microscopic still images have been taken at magnifications up to 500x and with exposure times down to 10 ns. In addition, two microscopic darkfield methods which provide a high contrast but a low light intensity of the image, have been selected to test their applicability down to an exposure time of 100 ns. Two examples for real-time cinematography of high-speed phenomena in microactuators are shown: the bouncing behavior of an electromagnetic microrelay and the bubble/jet formation of a thermal ink jet printhead.