Optical Systems for Multi-Sensor Endoscopes

Abstract

There is provided herein an optical system for a tip section of a multi-sensor endoscope, the system comprising: a front-pointing camera sensor; a front objective lens system; a side-pointing camera sensor; and a side objective lens system, wherein at least one of said front and side objective lens systems comprises a front and a rear sub-systems separated by a stop diaphragm, said front sub-system comprises, in order from the object side, a first front negative lens and a second front positive lens, said rear sub-system comprises, in order from the object side, a first rear positive lens, an achromatic sub-assembly comprising a second rear positive lens and a third rear negative lens, wherein the following condition is satisfied: f (first rear positive lens) ≦1.8f, where f is the composite focal length of the total lens system and f (first rear positive lens) is the focal length of said first rear positive lens.

What we claim is: 
     
         1 . An optical system for a tip section of a multi-sensor endoscope, the system comprising:
 a front-pointing camera sensor;   a front objective lens system;   a side-pointing camera sensor; and   a side objective lens system,   wherein at least one of said front and side objective lens systems comprises a front and a rear sub-systems seperated by a stop diaphragm,   said front sub-system comprises, in order from the object side, a first front negative lens and a second front positive lens,   said rear sub-system comprises, in order from the object side, a first rear positive lens, an achromatic sub-assembly (optionally, a compound achromatic sub-assembly) comprising a second rear positive lens and a third rear negative lens, wherein the following condition is satisfied:   f (first rear positive lens) ≦1.8f, where f is the composite focal length of the total lens system and f (first rear positive lens)  is the focal length of said first rear positive lens.   
     
     
         2 . The optical system according to  claim 1 , wherein said front sub-system further comprises an additional front meniscus lens disposed between said first front negative lens and said second front positive lens. 
     
     
         3 . The optical system according to  claim 1 , wherein said rear sub-system further comprises a rear protective glass situated between said third rear negative lens and said front-pointing and/or side-pointing camera sensor, wherein said rear protective glass is adapted to protect a detector array of said front-pointing and/or side-pointing camera sensor. 
     
     
         4 . The optical system according to  claim 1 , wherein:
 f (first rear positive lens) =1.8f, where f is the composite focal length of the total lens system and f (first rear positive lens)  is the focal length of said first rear positive lens.   
     
     
         5 . The optical system according to  claim 1 , wherein said front-pointing camera sensor and said front objective lens system are adapted to provide a Depth of Focus (DOF) of between 4 and 110 mm. 
     
     
         6 . The optical system according to  claim 5 , wherein said front-pointing camera sensor and said front objective lens system are adapted to provide a Depth of Focus (DOF) of between 3.5 and 50 mm. 
     
     
         7 . The optical system according to  claim 1 , wherein said front-pointing camera sensor and said front objective lens system are adapted to provide an effective spatial resolution of at least 60 lines per mm at Depth of Focus (DOF) of between 5 and 50 mm. 
     
     
         8 . The optical system according to  claim 1 , wherein said front-pointing camera sensor and said front objective lens system are adapted to provide an effective angular resolution of about 2′ per degree or less at Depth of Focus (DOF) of between 5 and 50 mm. 
     
     
         9 . The optical system according to  claim 1 , wherein said front-pointing camera sensor and said front objective lens system are adapted to provide a Field of View (FOV) of about 150 degrees or more. 
     
     
         10 . The optical system according to  claim 9 , wherein said front-pointing camera sensor and said front objective lens system are adapted to provide a Field of View (FOV) of about 170 degrees or more. 
     
     
         11 . The optical system according to  claim 1 , wherein said front-pointing camera sensor and said front objective lens system have a total optical length of about 5 mm or less. 
     
     
         12 . The optical system according to  claim 1 , wherein said side-pointing camera sensor and said side objective lens system are adapted to provide a Depth of Focus (DOF) of between 3.5 and 50 mm. 
     
     
         13 . The optical system according to  claim 1 , wherein said side-pointing camera sensor and said side objective lens system are adapted to provide a Depth of Focus (DOF) of between 3 and 30 mm. 
     
     
         14 . The optical system according to  claim 1 , wherein said side-pointing camera sensor and said side objective lens system are adapted to provide an effective spatial resolution of at least 60 lines per mm at Depth of Focus (DOF) of between 5 and 50 mm. 
     
     
         15 . The optical system according to  claim 1  wherein said side-pointing camera sensor and said side objective lens system are adapted to provide an effective angular resolution of about 2′ per degree or less at Depth of Focus (DOF) of between 5 and 50 mm. 
     
     
         16 . The optical system according to  claim 1 , wherein said side-pointing camera sensor and said side objective lens system are adapted to provide a Field of View (FOV) of about 150 degrees or more. 
     
     
         17 . The optical system according to  claim 1 , wherein said side-pointing camera sensor and said side objective lens system are adapted to provide a Field of View (FOV) of about 170 degrees or more. 
     
     
         18 . The optical system according to  claim 1 , wherein said side-pointing camera sensor and said side objective lens system have a total optical length of about 5 mm or less. 
     
     
         19 . The optical system according to  claim 1 , wherein the diameter of said first front negative lens is 2.5 mm or less. 
     
     
         20 . An objective lens system for at least one of a front-pointing and side-pointing camera sensors of a multi-sensor endoscope, the objective lens system comprising:
 a front and a rear sub-systems separated by a stop diaphragm, wherein   said front sub-system comprises a first front negative lens and a second front positive lens, and   said rear sub-system comprises a first rear positive lens, an achromatic sub-assembly (optionally, a compound achromatic sub-assembly) comprising a second rear positive lens and a third rear negative lens,   wherein the following condition is satisfied:   f (first rear positive lens) ≦1.8f, where f is the composite focal length of the total lens system and f(first rear positive lens) is the focal length of said first rear positive lens.   
     
     
         21 . A tip section of a multi-sensor endoscope comprising an optical system comprising:
 a front-pointing camera sensor;   a front objective lens system;   a side-pointing camera sensor; and   a side objective lens system,   wherein at least one of said front and side objective lens systems comprises a front and a rear sub-systems seperated by a stop diaphragm,   said front sub-system comprises a first front negative lens and a second front positive lens,   said rear sub-system comprises a first rear positive lens, an achromatic sub-assembly (optionally, a compound achromatic sub-assembly) comprising a second rear positive lens and a third rear negative lens, wherein the following conditions are satisfied:   f (first rear positive lens) ≦1.8f, where f is the composite focal length of the total lens system and f (first rear positive lens)  is the focal length of said first rear positive lens.