Modular rod lens assembly and method of making the same

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings, FIG.
1 illustrates an endoscope 10 equipped with a modular rod lens assembly 11 embodying the present invention.
The lens assembly comprises an outer tube or barrel 12 formed of a flexible and semirigid (i.
e.
, non-brittle) material such as stainless steel.
The proximal end of the normally-straight tube 12 is secured within the bore 13 of an eyepiece assembly designated generally by the numeral 14.
The eyepiece assembly includes a housing 15, an eyepiece 16 threadedly connected to the housing, and an eyepiece lens fitting 17 threadedly secured within an enlarged bore 18 of the housing.
Illumination for the field view is provided by a light-transmitting glass fiber bundle 19 which is operatively connected to a suitable light source (not shown) and which enters the eyepiece assembly through coupling 20.
Although a light-transmitting fiber bundle is important for endoscope operation, the bundle 19 is conventional as shown and is not essential for purposes of the present invention.
For that reason, in describing the rod lens assembly 11, that portion 19a of the fiber bundle which extends through the tube 12 will be regarded simply as a part of that outer tube or barrel.
Thus, the outer tube 12, including the fiber bundle 19a which lines that tube, defines a longitudinal bore 21 which supports a plurality of rod lens modules 22 in end-to-end relation.
In FIG.
2, the fiber bundle lining tube 12 is crescent-shaped in cross section with the result that bore 21 is offset from the longitudinal axis of the tube; however, if desired the fibers may be distributed uniformly to form an annular lining that defines a bore coaxial with the tube.
Each module 22 comprises a cylindrical rod lens 23 secured within a protective tubular sleeve or jacket 24.
A typical module is depicted in FIG.
3.
The rod lens shown in that figure happens to be composed of lens elements 23a and 23b cemented together to form a composite rod lens of a general type well known in the art