High-speed shutter for mirror cameras

Abstract

Highspeed mirror cameras are mainly used for investigations of quick processes in a wide spectral range ofradiation including ultraviolet and infrared regions (from 0.2 to 1 1 pm).High-speed shutters for these cameras must be non-selective and when opened must transmit the whole radiation without refraction, absorption and scattering.Electromechanical, electrodynamic and induction-dynamic shutters possess such properties because their optical channels contain no medium.Electromechanical shutters are devices where the displacement ofthe working blind which opens or closes an aperture is produced by a spring. Such shutters are relatively slow and are capable of closing an aperture of 50 mm in diameter in 10 -15 ms[1].Electrodynamic and inductiondynamic shutters are devices where displacement of a blind is produced by the electromagnetic interaction between circuits with electric currents. In induction-dynamic shutter the secondary circuit is currentconducting blind itself in which a short-circuited loop forms. The latter is more quick because of the lower mass of its moveable secondary circuit.For this reason inductiondynamic shutters with a flat primary circuit coil and a tightly fitted to it load-bearing aluminum plate have been investigated. The blind which opens or closes an aperture was attached to this plate.The dependencies of cut-off time on the form, size and the number ofturns of the primary circuit coil, on size, type of material, thickness and weight of the load-bearing plate and the blind, a well as on capacitance in the discharge circuit and the capacitor voltage have been investigated.The influence of the environmental atmosphere on the cut-off time was also studied. For this purpose the shutter was placed into the chamber where vacuum up to 10 atm could be produced.As a result the values of the above mentioned parameters have been optimized and the designs of the shutters which are shown in Fig. 1 and Fig.2 have been developed. 152 SPIE Vol. 3516 • 0277-786X/99/$1O.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/19/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx