CPC G02B 13/009 (2013.01) [G02B 15/1461 (2019.08); G02B 15/20 (2013.01)] | 17 Claims |
1. An optical system, comprising:
a light folding element configured to reflect received light onto an optical axis;
at least three lens groups, each lens group comprising one or more respective lens elements, each lens group positioned along the optical axis so as to receive and refract at least a portion of the light directed along the optical axis; and
at least three actuators, each actuator coupled with a respective one of the lens groups, each of the actuators configured to:
receive a corresponding signal indicating a corresponding direction of displacement along the optical axis for the respective lens group; and
in response to receipt of the corresponding signal, move the respective lens group along the optical axis by a corresponding displacement in the corresponding direction of displacement,
wherein to increase a focal length of the optical system, the at least three actuators are configured to:
move a particular one of the at least three lens groups along the optical axis in a direction toward an image plane toward which the received light is directed; and
move two others of the at least three lens groups along the optical axis in another direction that is away from the image plane;
wherein an f-number of the optical system is less than f/3.0.
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