Abstract: Photometer means usable in scientific instrument having a video display means such as a scanning electron microscope including means for matching the intensity of the video display to the exposure time selected for photographing said video display taking into consideration such film characteristics as film speed, reciprocity failure and exposure time.

Abstract: A high-speed circuit for causing the corpuscular particle beam of a corpuscular particle microprobe such as a scanning electron microscope to be periodically and sequentially displaced from its normal path so as to, in effect, interrupt the beam's bombardment of a specimen during certain of the scanning cycle of the microprobe. In an elementary form, it includes a deflection circuit having a pair of deflection plates disposed such that the beam passes therebetween and a high-speed driving circuit to power the deflection plates, in order to achieve desired rapid response times. The driving circuit includes a high-speed switch of the type of a vertical MOSFET which is, in turn, connected to a current limiting resistance load which, in turn, is connected to the voltage source for the deflection plates.