Method and apparatus for optical stabilization

Abstract

A method and apparatus for controlling the attitude of a vehicle (such as an aircraft) in a space having at least two opposed viewable regions, each region being viewed by a respective first sensor for sensing a first frequency band of electromagnetic radiation and a respective second sensor for sensing a second frequency band of electromagnetic radiation, wherein respective first and second data sets from the first and second sensors for each regions are produced, these second data sets are subsequently modified and combined with the first data sets to form respective third data sets for each region. The attitude of the vehicle is then adjusted until the third data sets are substantially equal.

1 . A method for reducing effects of a source of electromagnetic radiation when viewing a region to detect variations in background intensity in said region, comprising:
 a) producing a first data set from a first sensor viewing said region in a first frequency band of electromagnetic radiation;   b) producing a second data set from a second sensor viewing said region in a second different frequency band of electromagnetic radiation;   c) modifying said second data set; and   d) combining said modified second data set with said first data set, whereby said effects of said electromagnetic source are reduced relative to said variations in background intensity.   
   
   
       2 . A method as claimed in  claim 1 , wherein measurements by said second sensor are more sensitive to said electromagnetic source than to intensity differences between variations in background intensity in said second frequency band. 
   
   
       3 . A method as claimed in  claim 1 , wherein said modifying includes multiplying said second data set by a predetermined factor. 
   
   
       4 . A method as claimed in  claim 1 , wherein said combining includes finding a difference between said modified second data set and said first data set. 
   
   
       5 . A method as claimed in  claim 1 , wherein said producing said first and second data sets further includes logarithmically compressing said data sets. 
   
   
       6 . A method as claimed in  claim 1 , wherein said first frequency band is in the ultraviolet, said second frequency band is in the green spectra, and said source is the sun. 
   
   
       7 . A method as claimed in  claim 1 , wherein at least of one said first and second frequency bands is or is in the millimeter wavelength band. 
   
   
       8 . An apparatus for reducing effects of a source of electromagnetic radiation when viewing a region to detect variations in background intensity in said region, comprising:
 a) a first connection providing a first data set from a first sensor viewing said region in a first frequency band of electromagnetic radiation;   b) a second connection providing a second data set from a second sensor viewing said region in a second different frequency band of electromagnetic radiation;   c) a processor coupled to said first and second connections and which modifies said second data set and combines said modified second data set with said first data set, whereby said effects of said electromagnetic source are reduced relative to said variations in background intensity.   
   
   
       9 . An apparatus as claimed in  claim 8 , wherein measurements by said second sensor in said second frequency band are more sensitive to said electromagnetic source than to intensity differences between variations in background intensity in said second frequency band. 
   
   
       10 . An apparatus as claimed in  claim 8 , wherein said processor multiplies said second data set by a predetermined factor. 
   
   
       11 . An apparatus as claimed in  claim 8 , wherein said processor finds a difference between said modified second data set and said first data set. 
   
   
       12 . An apparatus as claimed in  claim 8 , wherein said first frequency band is in the ultraviolet, said second frequency band is in the green spectra, and said source is the sun. 
   
   
       13 . An apparatus as claimed in  claim 8 , wherein at least of one said first and second frequency bands is or is in the millimeter wavelength band.