High dynamics multispectral opto-electrical receiver system
First Claim
1. A high dynamics multispectral opto-electrical receiver system incorporating optical means for the reception and focusing of light radiation to form the image of the field observed on an opto-electrical transducer for video signal detection, said optical means being provided with attenuation and optical filtering means for the selection of two different spectral bands of operation and for providing a variable light transmission, said attenuation and optical filtering means comprising a transparent disc support, layers deposited on the said support along two sectors of a circular ring to provide filtering in the said two bands respectively and attenuation variation as a function of the angular position of the disc, said layers comprising two graded angular attenuators symetrically produced with respect to a reference diameter, said sectors being joined at one end by a high density area to seal the light transmission, and separated at the other end by a minimum density area to produce substantially no attenuation, and a servo-control device to rotate said disc and to control its angular position as a function of the video signal value.
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Abstract
System in which multispectral filtering and variable optical attenuation are effected on the same support. In the case of a supporting disc it has two angular graduated attenuators produced symmetrically with respect to a referenced diameter. Each attenuator also forms optical filters in a given spectral band so as to be able to operate in two separate bands. The disc is positioned in the vicinity of a relay objective positioned between the receiving objective and the opto-electrical transducer. The detected signal supplies a loop controlling the angular position of the disc. The disc is controlled in such a way that the switching of the band takes place on passing through the maximum density zones of the attenuators.
36 Citations
4 Claims
- 1. A high dynamics multispectral opto-electrical receiver system incorporating optical means for the reception and focusing of light radiation to form the image of the field observed on an opto-electrical transducer for video signal detection, said optical means being provided with attenuation and optical filtering means for the selection of two different spectral bands of operation and for providing a variable light transmission, said attenuation and optical filtering means comprising a transparent disc support, layers deposited on the said support along two sectors of a circular ring to provide filtering in the said two bands respectively and attenuation variation as a function of the angular position of the disc, said layers comprising two graded angular attenuators symetrically produced with respect to a reference diameter, said sectors being joined at one end by a high density area to seal the light transmission, and separated at the other end by a minimum density area to produce substantially no attenuation, and a servo-control device to rotate said disc and to control its angular position as a function of the video signal value.
- 3. A high dynamics multispectral opto-electrical receiver system incorporating optical means for the reception and focusing of light radiation to form the image of the field observed on an opto-electrical transducer for video signal detection, said optical means being provided with attenuation and optical filtering means for the selection of two different spectral bands of operation and for providing a variable light transmission, said attenuation and optical filtering means comprising a transparent disc support, layers deposited on the said support along two sectors of a circular ring to provide filtering in the said two bands respectively and attenuation variation as a function of the angular position of the disc, said layers comprising two graded angular attenuators symetrically produced with respect to a reference diameter, said sectors being joined at one end by a high density area to seal the light transmission, and separated at the other end by a minimum density area to produce substantially no attenuation, and a servo-control device to rotate said disc and to control its angular position as a function of the video signal value, said servo-control device incorporating means for controlling the rotation of the disc in an opposite direction during a switching of the operating band in such a way as to change filter on passing through maximum density attenuation zones of the graded attenuators and through the said high density area.
Specification