GB458106A - Improvements in instruments for testing for colour perception - Google Patents

Abstract

458,106. Sight-testing apparatus. RAYNER OPTICAL CO., Ltd., PIKE, J., and HOBSON, E. N., 100, New Bond Street, London. June 12, 1935, No. 16979. [Class 97 (i)] An apparatus for testing colour perception comprises two discs rotatable in a casing and having apertures carrying colour filters, light from a lamp carried in the casing passing through the filters and through apertures in a wall of the casing to the eyes of the patient. The intensity of the beams may be varied by placing neutral filters in the beams, and the size of the beams may be varied by the insertion of stops. The discs 15, rotatable on spindles 12 by knob 13, are arranged in a casing 1 to be on either side of a housing 6 containing the lamp 11. Light from the lamp passes through the colour filters 17 and through apertures 18 in the wall 3, to the eyes of the patient either directly or by reflection, so that the light is seen by both eyes simultaneously. The discs carry indicia 23, Fig. 3, observable through lenses 20, Fig. 2, to indicate the colour of the filters opposite the apertures 18, the discs being held in position by spring-loaded pins 24. The spindles 12 also carry plates 26 bearing neutral filters 30 of different densities which on rotation into the beam by means of levers 28 will modify its intensity. Plates 37 having a plurality of stop apertures 38 may be rotated about axes 12 to limit the size of the beams and may be held in position by spring-pressed pins 41 engaging recesses in plates 43. A resistance may be provided to varying the intensity of the light.