Abstract: In order to regulate the absorptance of an electrochromic layer, the absorptance of the layer is measured optically. The signal derived therefrom is compared with a guide value and fed to a controller which has a dead zone between two hysteresis regions (at switch points), and charges are fed to or removed from the layer as required. Preferred fields of use are lenses, particularly eyeglass lenses, filters and dimmable mirrors to which an electrochromic layer is applied with provision for controlled change of its absorptance.

Abstract: The invention contemplates a refractometer that images a test mark on the retina and is automatic in its determination of both refractive-power and astigmatism parameters, for the eye under examination. An imaging lens serves both (1) to project the test mark to the retina and (2) to convey that image for refocus external to the eye, to a scanner having the ability to digitally establish the eye's focal length. In the process of establishing the eye's focal length, the instrument automatically positions the imaging lens to best serve infinity viewing by the eye, and a prism then rotates the test mark while the scanner photoelectrically tracks the refocused image for the angles at which response is at a maximum, thus establishing astigmatism parameters. The instrument provides selective direct indication or print-out of the automatically determined parametric values.

Abstract: Photographic camera shutter apparatus having at least one drivable control part arranged for reciprocation for controlling the photographic light admitted to the camera, e.g. a diaphragm aperture ring or a shutter blade ring, and an electromagnetic driving system for reciprocating the control part, including at least one corresponding assembly having opposed coacting reciprocally energizable electromagnetic field coils stationarily arranged in spaced apart relation and providing an intervening magnetic field space therebetween and movable permanent magnets arranged for reciprocation along such intervening field space in response to the corresponding energization of the stationary field coils and operatively connected for driving the control part in question concordantly for reciprocation thereof, whereby to control the photographic light admitted to the camera in dependence upon the energization of the field coils.

Abstract: The invention contemplates wireless remote-control of a camera or the like, as from within the field of view of the camera, and using control radiation which is essentially outside the spectral response of the camera. Control is effected by selective operation of a pulsed transmitter of the control radiation, and by generating in a receiver at the camera an electrical signal for camera control. Various modifications and embodiments are disclosed, including selective remote-control of one or more different camera functions.