Spatial and spectral filtering apertures and optical imaging systems including the same

Abstract

A filter includes a central filter region, the central filter region to transmit a first wavelength range, a peripheral filter region, the peripheral filter region to block a second wavelength range, and a transition filter region between the central and peripheral filter regions, the transition filter region to transmit or block the second wavelength range differently than the second wavelength range is to be transmitted or blocked in the central and peripheral filter regions. More generally, there may be “N” regions and up to N−1 transition regions.

1 . (canceled) 
     
     
         2 . A filter, comprising:
 a central filter region, the central filter region to transmit a first wavelength range;   a peripheral filter region, the peripheral filter region to block a second wavelength range and to transmit the first wavelength range; and   a transition filter region between the central and peripheral filter regions, wherein the transition filter region includes a plurality of first portions and a plurality of second portions arranged in a pattern configured to apodize the boundary between the central and peripheral filter regions, wherein the first portions are to block the second wavelength range and the second portions are to transmit the second wavelength range.   
     
     
         3 . The filter as claimed in  claim 2 , wherein the central filter region is to block the second wavelength range. 
     
     
         4 . The filter as claimed in  claim 2 , wherein the central filter region is to transmit the second wavelength range and the transition filter region is to transmit more of the second wavelength range than the peripheral filter region and less of the second wavelength range than the central filter region. 
     
     
         5 . The filter as claimed in  claim 4 , wherein the transition filter region is to gradually change transmission of the second wavelength range from the central filter region to the peripheral filter region. 
     
     
         6 . The filter as claimed in  claim 2 , wherein the first portions of the transition filter region are of a same material as the peripheral filter region. 
     
     
         7 . The filter as claimed in  claim 2 , wherein the filter substantially equalizes point spread functions of the first and second wavelength ranges. 
     
     
         8 . The filter as claimed in  claim 2 , wherein the first and second wavelength ranges partially overlap. 
     
     
         9 . The filter as claimed in  claim 2 , wherein the first and second wavelength ranges do not overlap. 
     
     
         10 . A kit comprising:
 a filter as recited in  claim 2 ; and   a beam splitter to split the first and second wavelength ranges.   
     
     
         11 . A kit comprising:
 a filter as recited in  claim 2 ; and   a plurality of relays.   
     
     
         12 . A kit comprising:
 a filter as recited in  claim 2 ; and   an objective lens.   
     
     
         13 . An endoscope comprising:
 a filter as recited in  claim 2 .   
     
     
         14 . The endoscope as recited in  claim 13 , wherein the filter is positioned at or near a system aperture or conjugate thereof of the endoscope. 
     
     
         15 . The endoscope as recited in  claim 13 , wherein the filter is not positioned at or near a system aperture or conjugate thereof of the endoscope. 
     
     
         16 . A method of filtering at least a first wavelength range and a second wavelength range using a filter, the method comprising:
 transmitting the first wavelength range in a central region of the filter;   blocking the second wavelength range and transmitting the first wavelength range in a peripheral region of the filter; and   apodizing the boundary between the central and peripheral filter regions, by in a transition filter region between the central and peripheral filter regions blocking the second wavelength range in first portions of the transition filter region and transmitting the second wavelength range in second portions of the transition filter region.   
     
     
         17 . The method as claimed in  claim 16 , further comprising blocking the second wavelength range in the central region of the filter. 
     
     
         18 . The method as claimed in  claim 16 , further comprising transmitting the second wavelength range in the central region of the filter, wherein the transition portion transmits more of the second wavelength range than for the peripheral portion and less of the second wavelength range than the central portion.