Optical filter tuned by rotation and comprising a Fabry-Perot interferometer

DETAILED DESCRIPTION The present invention consists in a rotation tuned optical filter comprising a Fabry-Perot type interferometer disposed between an optical source and an optical receiver wherein said interferometer filters an input optical signal from said optical source, said input optical signal propagates substantially in a single mode, said interferometer supplies a filtered optical signal to said optical receiver which comprises a receiving surface which integrates the power density of said filtered optical signal, and said filter comprises means for modifying the position of said filtered optical signal relative to said receiving surface of said optical receiver.
This can optimize the energy integrated by the receiving surface of the optical receiver.
In one preferred application of the invention the optical source comprises a monomode input optical fiber cooperating with a collimator lens and the optical receiver comprises a focussing lens cooperating with an output optical fiber, the surface of the core of the output optical fiber constituting the receiving surface.
This optimizes the transmission of energy of the filtered optical signal as a function of the interferometer rotation angle.
This optimization is achieved by concentrating the maximum optical energy on the focussing lens so that the maximum energy is transmitted coaxially to the output optical fiber.
In a first embodiment of the invention the means for modifying the relative position of the filtered optical signal relative to the receiving surface of the optical receiver comprise a plate by which the filtered optical signal is refracted.
This plate is preferably at the same angle to the input optical signal as the interferometer.
In this case the plate and the interferometer are fixed relative to each other and the transmission characteristics are optimized over all of the tuning range, i.
e.
over all of the free spectral range.
The filtered optical signal flux is the integral of the filtered optical signal power density