Prism construction for simultaneous zero-degree and oblique illumination of a stereoscopic surgical microscope
View Patent ↗The invention concerns an apparatus for simultaneous zero-degree and oblique illumination for an optical viewing device, in particular a stereoscopic surgical microscope, which contains a shiftable prism combination ( 3 ) for deflecting a first illumination sub-beam a long distance from the optical axis ( 12 ) of the main objective in order to obtain an oblique illumination beam ( 9 ) (oblique illumination), and for deflecting a second illumination sub-beam ( 8 ) a short distance from the optical axis ( 12 ) of the main objective in order to obtain a zero-degree illumination ( 8 ).
1. An optical system for use in combination with a stereoscopic microscope of a type including a main objective ( 10 ) having an optical axis ( 12 ) and two stereoscopic observation beam paths ( 11 a , 11 b ) each having a respective lens tube associated therewith, said optical system being used for simultaneous zero-degree and oblique illumination of an observed specimen ( 13 ), said optical system comprising:
an illumination beam ( 7 ); and
a prism combination ( 3 ) arranged between said main objective ( 10 ) and said lens tubes ( 17 ) to receive said illumination beam, said prism combination splitting said illumination beam into a first illumination sub-beam ( 9 ) and a second illumination sub-beam ( 8 ) and deflecting said first and second sub-beams to said main objective, said first illumination sub-beam being deflected along a path spaced relatively far from said optical axis to obtain said oblique illumination and said second illumination sub-beam being deflected along a path relatively close to said optical axis to obtain said zero-degree illumination;
wherein a portion of said prism combination ( 3 ) directed toward said two stereoscopic observation beam paths tapers symmetrically toward said optical axis ( 12 ) of said main objective ( 10 ) in order to achieve optimum and vignetting-free observation, and wherein said prism combination ( 3 ) is radially movable relative to said optical axis ( 12 ) of said main objective ( 10 ).
2. The optical system as defined in claim 1 , wherein said prism combination ( 3 ) is centerable relative to said optical axis ( 12 ) of said main objective ( 10 ) such that when said prism combination ( 3 ) is in a centered state, said zero-degree illumination of said specimen ( 13 ) is obtained using said second illumination sub-beam ( 8 ) and said oblique illumination of said specimen ( 13 ) is obtained using said first illumination sub-beam ( 9 ).
3. The optical system as defined in claim 2 , wherein said prism combination ( 3 ) can be decentered relative to said optical axis ( 12 ) of said main objective ( 10 ) such that when said prism combination ( 3 ) is in a decentered state, an oblique illumination is obtained using both said first and second illumination sub-beams ( 9 , 8 ).
4. The apparatus as defined in claim 3 , wherein said prism combination ( 3 ) is movable radially relative to said optical axis ( 12 ) of said main objective ( 10 ) in manual or motorized fashion.
5. The apparatus as defined in claim 4 , further comprising a motorized drive system ( 14 ) for moving said prism combination ( 3 ) radially relative to said optical axis ( 12 ) of said main objective ( 10 ).
6. The apparatus as defined in claim 5 , wherein said motorized drive system ( 14 ) is coupled to a distance measurement system ( 15 ) which, in an operating state and when a distance to the patient's eye is too short, moves said prism combination ( 3 ) out of said centered state.
7. The apparatus as defined in claim 5 , wherein said motorized drive system ( 14 ) is coupled to a light-intensity measurement system ( 16 ) which, in an operating state and when a luminance is too high, shifts said prism combination ( 3 ) out of said centered state.
8. The optical system as defined in claim 1 , wherein said prism combination ( 3 ) is movable through a continuous range of radial positions relative to said optical axis ( 12 ) of said main objective ( 10 ), whereby any illumination angle within a continuous range of illumination angles is selectable.
9. An optical system for use in combination with a stereoscopic microscope of a type including a main objective ( 10 ) having an optical axis ( 12 ) and two stereoscopic observation beam paths ( 11 a , 11 b ) each having a respective lens tube associated therewith, said optical system being used for simultaneous zero-degree and oblique illumination of an observed specimen ( 13 ), said optical system comprising:
a light source ( 1 ) and an illuminating optical system ( 2 ) for providing an illumination beam ( 7 ); and
a prism combination ( 3 ) arranged between said main objective ( 10 ) and said lens tubes ( 17 ) to receive said illumination beam, said prism combination splitting said illumination beam into a first illumination sub-beam ( 9 ) and a second illumination sub-beam ( 8 ) and deflecting said first and second sub-beams to said main objective, said first illumination sub-beam being deflected along a path spaced relatively far from said optical axis to obtain said oblique illumination and said second illumination sub-beam being deflected alone a path relatively close to said optical axis to obtain said zero-degree illumination;
wherein a portion of said prism combination ( 3 ) directed toward said two stereoscopic observation beam paths tapers symmetrically toward said optical axis ( 12 ) of said main objective ( 10 ) in order to achieve optimum and vignetting-free observation, and wherein said prism combination ( 3 ) is radially movable relative to said optical axis ( 12 ) of said main objective ( 10 ) together with said illuminating optical system ( 2 ) and said light source ( 1 ).