Limits of continuous frequency tuning of injection lasers with selective external cavities

A method for mechanical coupling of the shifts of the band of a selective element to a mode of an injection laser with an external cavity is considered. The method reduces to finding the optimal variant of plane-parallel motion of one of the cavity elements. Solutions are found for important modifications of external cavity systems (in the case of rotation about a fixed axis). Estimates are obtained of the possible width of the continuous tuning range and of the sensitivity of the tuning system to alignment errors.