Optical recording-reading head using an adjustable mount for pivoting mirror

Claim 1

Optical device for recording or retrieving information signals at a surface of an information medium, said device comprising: solid state laser source means for emitting a collimated beam of rectilinearly polarized radiant energy; lens means for focussing said radiant energy at said surface; polarization splitting optical means refracting said collimated beam for feeding said lens means; quarter wave polarization means arranged between said surface and said polarization splitting optical means for converting the rectilinear polarization of said emitted radiant energy into circular polarization; and photodetector means arranged for collecting reflected radiant energy emerging from the portion of said surface illuminated with said focussed radiant energy, said reflected radiant energy being refracted by said lens means, said quarterwave polarization means and said polarization splitting optical means; said polarization splitting optical means having a first and a second prism shaped refracting element fitting one another along a common polarization splitting face; said first refracting element having an entry face for collecting said collimated beam; said second refracting element having an axit face for supplying said reflected radiant energy to said photodetector means, a reflective face and an exchange face optically coupled with said lens means; said entry face being arranged for obliquely receiving said collimated beam; said exit face and said exchange face being arranged for respectively refracting at normal incidence said reflected radiant energy to said photodetector means and said radiant energy to said lens means respectively; a pivoting mirror arranged downstream of said polarization splitting refringent means for reflecting toward said lens means the radiant energy emerging from said exchange face; and an adjustable mount for said pivoting mirror comprising a cradle shaped base having a sliding surface with a center of curvature O, a pivoting seat having a sliding surface with the same curvature as the preceding surface and against which it is applied, said mirror being supported by the pivoting seat so that the center of curvature O is in the reflecting plane of the mirror.