Filter for use with imaging endoscopes

Abstract

A fluorescence endoscopy video system includes a multi-mode light source that produces light for white light and fluorescence imaging modes. A filter is positioned at the distal end of an imaging endoscope so that the endoscope can produce fluorescence and white light images of a tissue sample.

1 . A filter assembly for use with an imaging endoscope, comprising: 
 a filter adapted to be positioned in front of an imaging lens of the endoscope, the filter blocking excitation light from reaching an image sensor of the endoscope so that the image sensor can produce fluorescence images, the filter also passing an amount of blue light so that the image sensor can produce white light images of the tissue.    
   
   
       2 . The filter assembly of  claim 1 , wherein the filter blocks excitation light having wavelengths in a range of 370 to 450 nm.  
   
   
       3 . The filter assembly of  claim 2 , wherein the filter passes light having wavelengths in a range of 450-480 nm.  
   
   
       4 . The filter assembly of  claim 1 , further comprising means for securing the filter to a distal end of the endoscope.  
   
   
       5 . The filter assembly of  claim 4 , wherein the means for securing the filter includes one or more tabs that are secured to the endoscope.  
   
   
       6 . The filter assembly of  claim 4 , wherein the means for securing the filter includes an adhesive.  
   
   
       7 . The cap of  claim 4 , wherein the means for securing the filter includes a magnet.  
   
   
       8 . The cap of  claim 1 , wherein the means for securing the filter includes a sleeve that fits over a distal end of the endoscope.  
   
   
       9 . A system for producing fluorescence and white light images with an imaging endoscope that includes an image sensor, comprising: 
 a removable filter that is placed in front of an imaging lens of the endoscope that filters excitation light from reaching the image sensor and passes an amount of blue light;    an image processor that produces images from image signals received from the image sensor;    a light source for producing excitation light for use in a fluorescence imaging mode and illumination light for use in a white light imaging mode, wherein the illumination light produced by the light source compensates for the effects of the filter so that the images produced from the image sensor can be white balanced.    
   
   
       10 . The system of  claim 9 , wherein the illumination light produced by the light source has an increased amount of blue light in a wavelength band that passes through the filter compared with an amount of red and green light in the illumination light.  
   
   
       11 . The system of  claim 9 , wherein the illumination light produced by the light source has a decreased amount of green and red light so that that the red, green and blue light received at the image sensor have substantially equal magnitudes.  
   
   
       12 . The system of  claim 9 , wherein the light source produces an amount of reflectance light when operating in a fluorescence imaging mode.  
   
   
       13 . The system of  claim 12 , wherein the reflectance light is red light.  
   
   
       14 . The system of  claim 12 , wherein the reflectance light is green light.  
   
   
       15 . The system of  claim 12 , wherein the reflectance light is blue light having wavelengths that pass through the filter.  
   
   
       16 . The system of  claim 9 , wherein the image sensor is a color image sensor and the illumination light includes red, green and blue spectral components.  
   
   
       17 . The system of  claim 9 , wherein the image sensor is a monochrome sensor and the illumination light includes sequentially produced red, green and blue spectral components.