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 . (canceled) 
     
     
         2 . A fluorescence endoscopy video system comprising:
 a multi-mode light source for producing various light outputs comprising optical filters that selectively alter the spectral characteristics of the light produced by the light source, the optical filters comprising:
 a light source filter for blue light fluorescence excitation and reflectance imaging at blue wavelengths; 
 a light source filter for red light reflectance imaging at red wavelengths; and 
 a light source filter for green light reflectance imaging at green wavelengths, wherein said filters are operable such that the light source can produce sequential red, green, and blue light for white light imaging or continuous fluorescence excitation light for fluorescence imaging; 
   an endoscope for directing the light from the light source into a patient to illuminate a tissue sample and to collect the reflected light and fluorescence light produced by the tissue;   a camera positioned to receive the light collected by the endoscope, the camera comprising:
 an image sensor; 
 a low light image sensor; 
 a beamsplitter for splitting the light received form the tissue sample into two beams and projecting the two beams onto the image sensor and low light image sensor; 
 a filter positioned in front of the low light sensor for selectively transmitting light of desired wavelengths; and 
 one or more optical imaging components that project images onto both the image sensor and low light image sensor; 
   an image processor coupled to the camera for digitizing, storing, processing, and encoding the image signals received from the image sensor and low light image sensor as video signals; and   a color video monitor that receives the video signals and displays them.   
     
     
         3 . The system of  claim 2 , wherein the camera is attached to the portion of the endoscope that remains outside of the body. 
     
     
         4 . The system of  claim 2 , wherein the camera is built into the insertion portion of the endoscope. 
     
     
         5 . The system of  claim 2 , wherein the beamsplitter directs a greater percentage of light collected by the endoscope to the low light image sensor and a lesser percentage to the image sensor. 
     
     
         6 . The system of  claim 2 , wherein the light source optical filter for blue light output transmits blue fluorescence excitation light and blocks light form the light source at wavelengths in a fluorescence detection wavelength band from reaching the camera to the extent that the light received by the camera is substantially composed of light resulting from tissue fluorescence and reflected fluorescence excitation light and minimally composed of light at wavelengths other than those used for fluorescence excitation originating from the light source. 
     
     
         7 . The system of  claim 6 , wherein a filter positioned in front of low light image sensor blocks reflected excitation light and transmits primarily fluorescence light to the extent that the light received by the low light image sensor is substantially composed of light resulting from tissue fluorescence and minimally composed of light originating from the light source. 
     
     
         8 . The system of  claim 7 , wherein the fluorescence light transmitted by the filter in front of the low light image sensor is green light. 
     
     
         9 . The system of  claim 8 , wherein the low light sensor has light sensitivity that varies synchronously with the light source output such that the light sensitivity of the low light image sensor is higher during the period of blue light output and lower at other times. 
     
     
         10 . The system of  claim 7 , wherein the fluorescence light transmitted by the filter in front of the low light image sensor is red light. 
     
     
         11 . The system of  claim 10 , wherein the low light sensor has light sensitivity that varies synchronously with the light source output such that the light sensitivity of the low light image sensor is higher during the period of blue light output and lower at other times. 
     
     
         12 . The system of  claim 8 , wherein the image processor creates a composite fluorescence/reflectance image comprising an image created from green fluorescence light acquired by the low light sensor during blue light excitation and an image created from blue reflectance light acquired by the image sensor, said images being superimposed and displayed in different colors on the color video monitor. 
     
     
         13 . The system of  claim 10 , wherein the image processor creates a composite fluorescence/reflectance image comprising an image created from red fluorescence light acquired by the low light sensor during blue light excitation and an image created from blue reflectance light acquired by the image sensor, said images being superimposed and displayed in different colors on the color video monitor. 
     
     
         14 . The system of  claim 8 , wherein the image processor creates a composite fluorescence/reflectance image comprising an image created from green fluorescence light acquired by the low light sensor during a period of blue light excitation, and an image created from red reflectance light acquired by the image sensor during a period of red light illumination, said images being superimposed and displayed in different colors on the color video monitor. 
     
     
         15 . The system of  claim 10 , wherein the image processor creates a composite fluorescence/reflectance image comprising an image created from green fluorescence light acquired by the low light sensor during a period of blue light excitation, and an image created from red reflectance light acquired by the image sensor during a period of red light illumination, said images being superimposed and displayed in different colors on the color video monitor. 
     
     
         16 . The system of  claim 8 , wherein the image processor creates a composite fluorescence/reflectance image comprising an image created from green fluorescence light acquired by the low light sensor during a period of blue light excitation, and an image created from green reflectance light acquired by the image sensor during a period of green light illumination, said images being superimposed and displayed in different colors on the video monitor. 
     
     
         17 . The system of  claim 10 , wherein the image processor creates a composite fluorescence/reflectance image comprising an image created from green fluorescence light acquired by the low light sensor during a period of blue light excitation, and an image created from green reflectance light acquired by the image sensor during a period of green light illumination, said images being superimposed and displayed in different colors on the video monitor. 
     
     
         18 . The system of  claim 8 , wherein the image processor creates a composite fluorescence/reflectance image comprising an image created from green fluorescence light, acquired by the low light sensor during a period of blue illumination, and an image created from red reflectance light acquired by the image sensor during a period of red illumination, said images being superimposed and displayed in different colors on the color video monitor, wherein said composite fluorescence/reflectance image is displayed simultaneously with a composite image, consisting of superimposed red, green, and blue reflectance light images acquired by the image sensor during periods of red, green, and blue illumination respectively. 
     
     
         19 . The system of  claim 8 , wherein the image processor creates a composite fluorescence/reflectance image comprising an image created from green fluorescence light acquired by the low light sensor during a period of blue illumination, and image created from blue reflectance light acquired by the image sensor during a period of blue illumination, said images being superimposed and displayed in different colors on a color video monitor, wherein said composite fluorescence/reflectance image is displayed simultaneously with a composite color image consisting of superimposed red, green, and blue reflectance light images acquired by the image sensor during periods of red, green, and blue illumination respectively. 
     
     
         20 . The system of  claim 10 , wherein the image processor creates a composite fluorescence/reflectance image comprising an image created from red fluorescence light acquired by the low light sensor during a period of light source blue illumination, and an image created from green reflectance light acquired by the image sensor during a period of green illumination, said images being superimposed and displayed in different colors on a color video monitor, wherein said composite fluorescence/reflectance image is displayed simultaneously with a composite color image, consisting of superimposed red, green, and blue reflectance light images acquired by the image sensor during period of red, green, and blue illumination respectively. 
     
     
         21 . The system of  claim 10 , wherein the image processor creates a composite fluorescence/reflectance image comprising an image created from red fluorescence light acquired by the low light sensor during a period of blue illumination, and an image created from blue reflectance light acquired by the image sensor during a period of blue illumination, said images being superimposed and displayed in different colors on a color video monitor, wherein said composite fluorescence/reflectance image is displayed simultaneously with a composite color image, consisting of superimposed red, green, and blue reflectance light images acquired by the image sensor during periods of red, green, and blue illumination respectively.