Real-scene dispersion sensor detecting two wavelengths and determining time delay

An optical system with compensation for atmospheric dispersive effects comprising:

• an input opening for allowing light from a scene into the system;
• an adjustable dispersive element coupled to the input opening for receiving the light from the scene and introducing spectral dispersion into the light, the amount of said spectral dispersion being adjustable;
• an aperture near an image plane of the optical system for receiving light from the adjustable dispersive element;
• a first light detecting system for receiving light from the aperture and detecting light of a first wavelength band in the light, said first light detecting system generating signals corresponding to the detected light of the first wavelength band;
• a second light detecting system for receiving the light from the aperture and detecting light of a second wavelength band in the light, said second light detecting system generating signals corresponding to the detected light of the second wavelength band;
• a processing circuit for receiving the signals from the first and second light detecting systems and sensing the relative time delay between the signals;
• and
• a control circuit for adjusting the spectral dispersion introduced by the adjustable dispersive element until the relative time delay sensed by the processing circuit is approximately zero.

A method of sensing optical dispersion comprising:

• scanning light from a scene through an aperture near an image plane of an optical system;
• detecting light of a first wavelength band in the light from the aperture;
• generating signals corresponding to the detected light of the first wavelength band;
• detecting light of a second wavelength band in the light from the aperture;
• generating signals corresponding to the detected light of the second wavelength band;
• and
• processing the generated signals to determine the relative time delay between the signals.

A method of compensating for atmospheric optical dispersive effects in a scanning optical system comprising:

• allowing light from a scene to be scanned into the scanning optical system;
• introducing spectral dispersion into the light with an adjustable dispersive element, the amount of said spectral dispersion being adjustable;
• passing light from the dispersive element through an aperture near an image plane of an optical system;
• detecting light of a first wavelength band in the light from the aperture;
• generating signals corresponding to the detected light of the first wavelength band;
• detecting light of a second wavelength band in the light from the aperture;
• generating signals corresponding to the detected light of the second wavelength band;
• processing the generated signals to determine the relative time delay between the signals;
• and
• adjusting the amount of spectral dispersion introduced by the adjustable dispersive element such that the time delay determined in the processing step is reduced to approximately zero.