Abstract: A retarder is presented for application in systems that transmit radiation through waveguides, such as microwave or millimeter-wave systems. The retarder is a compound device comprising multiple single element retarders, each of which introduces a retardation phase between different polarization states, and each of which is set at an orientation angle. The phases and angles are selected to maximize the operational bandwidth of the compound retarder. The selection of the phases and angles may be found by solving a set of simultaneous equations.

Abstract: A retarder is presented for application in systems that transmit radiation through waveguides, such as microwave or millimeter-wave systems. The retarder is a compound device comprising multiple single element retarders, each of which introduces a retardation phase between different polarization states, and each of which is set at an orientation angle. The phases and angles are selected to maximize the operational bandwidth of the compound retarder. The selection of the phases and angles may be found by solving a set of simultaneous equations.

Abstract: A multiple exposure control mechanism for a photographic camera is incorporated in a film magazine having a film advance gear mechanism for driving a film take-up spool in response to rotation of a magazine activating gear in a camera body as the camera shutter is cocked. The film advance gear mechanism includes a main gear driven by the magazine activating gear and carrying a pawl rotatable therewith and movable into and out of engagement with an intermediate gear driving the film take-up spool via a film take-up gear, and the multiple exposure control mechanism includes a cam carried on the main gear for controlling the pawl and an actuating button selectively operable to move the cam to position the pawl out of engagement with the intermediate gear and prevent film movement to permit multiple exposures of a film frame.