1. An imaging device comprising
a refractive imager lying in an optical path and comprising
a first lens group that forms an intermediate image of a scene on the optical path, wherein the first lens group comprises
a first-lens-group positive-power lens, and
a first-lens-group negative-power lens;
a second lens group that relays the intermediate image to a final image surface on the optical path, wherein the second lens group comprises
a second-lens-group negative-power lens, and
a second-lens-group positive-power lens; and
a third lens group that may be selectively inserted into the optical path between the first lens group and the second lens group and selectively removed from the optical path, wherein the third lens group comprises
a third-lens-group positive-power lens, and
a third-lens-group negative-power lens, wherein a location of the final image surface along the optical path is unchanged when the third lens group is inserted into the optical path and when the third lens group is removed from the optical path.
2. The imaging device of claim 1, further including
a foreoptics positioned on the optical path between the scene and the first lens group.
3. The imaging device of claim 1, further including
a field-switchable foreoptics positioned on the optical path between the scene and the first lens group.
4. The imaging device of claim 1, wherein locations of an exit pupil and a cold stop along the optical path are unchanged when the third lens group is inserted into the optical path and when the third lens group is removed from the optical path.
5. The imaging device of claim 1, wherein a location of an exit pupil, a cold stop, and a final image surface are unchanged when the third lens group is inserted into the optical path and when the third lens group is removed from the optical path, for light wavelengths in the medium-wavelength infrared range and the long-wavelength infrared range.
6. The imaging device of claim 1, further including
an imaging sensor positioned at the final image surface.
7. The imaging device of claim 1, wherein the first-lens-group positive-power lens lies on the optical pat between the scene and the first-lens-group negative-power lens.
8. The imaging device of claim 1, wherein the second-lens-group positive-power lens lies between the second-lens-group negative-power lens and the final image surface.
9. The imaging device of claim 1, wherein the third-lens-group positive-power lens lies on the optical path between the first lens group and the intermediate image, when the third lens group is inserted into the optical path.
10. The imaging device of claim 1, wherein the third-lens-group negative-power lens lies on the optical path between the intermediate image and the second lens group, when the third lens group is inserted into the optical path.
11. The imaging device of claim 1, wherein at least one of the first-lens-group positive-power lens and the second-lens-group positive-power lens is made of zinc selenide.
12. The imaging device of claim 1, wherein both the first-lens-group positive-power lens and the second-lens-group positive-power lens are made of zinc selenide.
13. The imaging device of claim 1, wherein at least one of the first-lens-group negative-power lens and the second-lens-group negative-power lens is made of barium fluoride.
14. The imaging device of claim 1, wherein both the first-lens-group negative-power lens and the second-lens-group negative-power lens are made of barium fluoride.
15. The imaging device of claim 1, wherein the third-lens-group positive-power lens is made of a material having a nominal composition of Ge33As12Se55 and a refractive index of about 2.5.
16. The imaging device of claim 1, wherein the third-lens-group negative-power lens is made of arsenic trisulfide.
17. An imaging device comprising
a refractive imager lying in an optical path and comprising
a first lens group that forms an intermediate image of a scene on the optical path, wherein the first lens group comprises
a first-lens-group positive-power lens, and
a first-lens-group negative-power lens, wherein the first-lens-group positive-power lens lies on the optical pat between the scene and the first-lens-group negative-power lens;
a second lens group that relays the intermediate image to a final image surface on the optical path, wherein the second lens group comprises
a second-lens-group negative-power lens, and a second-lens-group positive-power lens, wherein the second-lens-group positive-power lens lies between the second-lens-group negative-power lens and the final image surface;
a third lens group that may be selectively inserted into the optical path between the first lens group and the second lens group and selectively removed from the optical path, wherein the third lens group comprises
a third-lens-group positive-power lens, wherein the third-lens-group positive-power lens lies on the optical path between the first lens group and the intermediate image, when the third lens group is inserted into the optical path, and
a third-lens-group negative-power lens, wherein the third-lens-group negative-power lens lies on the optical path between the intermediate image and the second lens group, when the third lens group is inserted into the optical path; and,
a dual-wavelength imaging sensor located at the image surface, wherein the dual-wavelength imaging sensor is operable in a subrange of the 3\u20135 micrometer medium wavelength infrared range and a subrange of the 8\u201312 micrometer long wavelength infrared range, and wherein the materials of construction of the first lens group, the second lens group, and the third lens group are selected such that light of the subrange of the medium wavelength infrared range and the subrange of the long wavelength infrared range are both imaged onto the final image surface.
18. The imaging device of claim 17, further including
a telescope positioned on the optical path between the scene and the first lens group.
19. The imaging device of claim 17, wherein a location of the final image surface along the optical path is unchanged when the third lens group is inserted into the optical path and when the third lens group is removed from the optical path.
20. The imaging device of claim 17, wherein both the first-lens-group positive-power lens and the second-lens-group positive-power lens are made of zinc selenide.
21. The imaging device of claim 17, wherein both the first-lens-group negative-power lens and the second-lens-group negative-power lens are made of barium fluoride.
22. The imaging device of claim 17, wherein the third-lens-group positive-power lens is made of a material having a nominal composition of Ge33As2Se5 and a refractive index of about 2.5, and the third-lens-group negative-power lens is made of arsenic trisulfide.
23. An imaging device comprising
a refractive imager lying in an optical path and comprising
a first lens group that forms an intermediate image of a scene on the optical path, wherein the first lens group comprises
a first-lens-group positive-power lens, and
a first-lens-group negative-power lens;
a second lens group that relays the intermediate image to a final image surface on the optical path, wherein the second lens group comprises
a second-lens-group negative-power lens, and
a second-lens-group positive-power lens; and
a third lens group that may be selectively inserted into the optical path between the first lens group and the second lens group and selectively removed from the optical path, wherein the third lens group comprises
a third-lens-group positive-power lens, and
a third-lens-group negative-power lens; and
a dual-wavelength imaging sensor located at the final image surface, wherein the dual-wavelength imaging sensor is operable in a subrange of the 3\u20135 micrometer medium wavelength infrared range and a subrange of the 8\u201312 micrometer long wavelength infrared range, and wherein the materials of construction of the first lens group, the second lens group, and the third lens group are selected such that light of the subrange of the medium wavelength infrared range and the subrange of the long wavelength infrared range are both imaged onto the final image surface.
24. The imaging device of claim 23, further including a field-switchable foreoptics positioned on the optical path between the scene aud the first lens group.
25. The imaging device of claim 23, wherein a location of the final image surface along the optical path is unchanged when the third lens group is inserted into the optical path and when the third lens group is removed from the optical path.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An obstacle-detectable mobile device, comprising:
a frame body capable of traveling on a surface;
a control circuit mounted to said frame body for controlling traveling manner and direction of said frame body and configured to avoid obstacles obstructing the mobile device; and
a detection system mounted to said frame body and electrically connected with said control system, said detection system having an optical emitter, an optical receiver, and a reflector, said optical emitter emitting the light toward the surface at a given angle to define a projection area on the surface, said reflector facing said projection area, the light emitted to the projection area being reflected to said reflector to define a reflection area on said reflector, the reflection area being variably located on said reflector subject to a height that the surface is positioned, said optical receiver facing said reflector to define a receiving area on said reflector, the receiving area never overlapping the surface;
wherein the reflection area is overlapped with said receiving area when said optical emitter is spaced from the surface at a given distance; wherein the reflection area is not overlapped with the receiving area when said optical emitter is farther than the given distance from the surface; wherein said optical receiver being enabled to receive the light from said optical emitter is dependent on whether or not the receiving area is overlapped with the reflection area; and wherein the detection system of the mobile device is configured to reject ambient light pollution and avoid misdetection of obstacles.
2. The obstacle-detectable mobile robotic device as defined in claim 1, wherein said detection system comprises a housing and at least one spacer, said housing being mounted to said frame body and having an opening facing the surface, said spacer partitioning an inner space of said housing into two compartments; said optical emitter and receiver are located in said two compartments respectively; said reflector is located in said housing.
3. The obstacle-detectable mobile robotic device as defined in claim 1, wherein said reflector is a mirror surface or a metallic surface.
4. The obstacle-detectable mobile robotic device as defined in claim 1, wherein said optical emitter comprises an infrared emitter and said optical receiver comprises an infrared receiver.