Optical imaging systems having input beam shape control and path length control
Scanning optical beam imaging systems for imaging a surface with convex curvature are provided. The systems include a sphero-telecentric objective, wherein a scanning radius of curvature of the sphero-telecentric objective is greater than an apical radius of curvature of the surface and less than or equal to four times an apical radius of curvature of the surface.
1. A scanning optical beam imaging system for imaging a surface with convex curvature, the system comprising:
a source of optical radiation coupled to an optical fiber, wherein the optical fiber is coupled to an input of the scanning optical beam imaging system;
an input lens assembly configured to direct a beam of optical radiation from the optical fiber to a beam scanning assembly of the imaging system;
a lens assembly following the beam scanning assembly configured to transform the scanned beam of optical radiation into a set of non-parallel beams diverging from an optical axis of the lens assembly;
an objective lens assembly configured to transform the diverging set of non-parallel beams to a set of non-parallel rays converging in object space,
wherein the converging rays focus along a curved focal surface in object space between the objective lens assembly and a region of intersection of the rays;
wherein a radius of curvature of a focal surface is greater than zero and less than an axial distance between a distal objective lens surface and the focal surface; and
wherein the rays in object space are substantially perpendicular to the focal surface; and
wherein optical path lengths of the set of rays measured from the optical fiber input to the focal surface are substantially equal.
2. The system of claim 1 , wherein the objective lens assembly comprises lens elements arranged in four or fewer lens groups.
3. The system of claim 2 , wherein the objective lens assembly comprises an aspheric optical element.
4. The system of claim 1 , wherein the scanning optical beam imaging system is in a sample arm of an optical coherence tomography imaging system.
5. The system of claim 1 , wherein the input lens assembly comprises a set of at least three lens groups arranged along the optical axis between the optical fiber and the beam scanning assembly, wherein the input lens assembly further comprises:
at least one positive lens group;
at least one negative lens group;
means for adjusting positions of two of the lens groups along the optical axis between the optical fiber and the beam scanning assembly, wherein adjusting positions of two of the lens groups is performed one of in unison or separately; and
wherein positions of the lens groups along the optical axis map to an effective numerical aperture and an effective focal length of the imaging system.
6. An optical coherence tomography imaging system for imaging a curved surface, the system comprising:
a source of optical radiation coupled to an optical fiber, wherein the optical fiber is coupled in a sample arm of the optical coherence tomography imaging system to an input of the scanning optical beam imaging system;
an input lens assembly that directs a beam of optical radiation from the optical fiber to a beam scanning assembly;
a lens assembly following the beam scanning assembly configured to transform the scanned beam of optical radiation to a set of non-parallel beams diverging from an optical axis of the lens assembly;
an objective lens assembly configured to transform the diverging set of beams to a set of non-parallel rays converging in object space,
wherein the converging beams focus along a curved focal surface in object space between the objective lens assembly and a region of intersection of the rays;
wherein a radius of curvature of the focal surface is greater than zero and less than an axial distance between a distal objective lens surface and the focal surface;
wherein the rays in object space are substantially perpendicular to the focal surface; and
wherein optical path lengths of the set of rays measured from the optical fiber to the focal surface are substantially equal.
7. The system of claim 6 , wherein the objective lens assembly comprises lens elements arranged in four or fewer lens groups.
8. The system of claim 7 , wherein the objective lens assembly comprises an aspheric optical element.
9. The system of claim 6 , wherein the input lens assembly comprises a set of at least three lens groups arranged along the optical axis between the optical fiber and the beam scanning assembly, wherein the input lens assembly further comprises:
at least one positive lens group;
at least one negative lens group;
means for adjusting positions of two of the lens groups along the optical axis between the optical fiber and the beam scanning assembly, wherein adjusting positions of two of the lens groups is performed one of in unison or separately; and
wherein positions of the lens groups along the optical axis map to an effective numerical aperture and an effective focal length of the imaging system.