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Abstract
The equipment described consists of a micro-camera, and a flash tube unit. The micro-camera embodies a single leaf electromagnetic shutter. The leaf is inclined, and the lower side is silvered to reflect the microscope eyepiece light cone Into a viewing eyepiece. The shutter is actuated by a separate foot-operated timer, giving exposures from I sec.-I 300 sec. The flash-tube is used in conjunction with the camera, to give an exposure of 5 micro-seconds. It has mercury electrodes and forms a light source 3 millimetres in diameter, of great intrinsic brilliance. Using an I ford 109 filter, 94°, of the light output, as recorded on Panatomic X film, lies within the wavelength range 5000°-6400 A. This is the corrected range for achromatic objectives. The tube operates at 950 volts D.C., and dissipates 4 joules. The light output is sufficient for 2 mm. oil immersion phase contrast and dark ground photographs.
The photographic technique used by the author is described.