Patent ID: 7436587

Claim:
An imaging device having a variable focusing distance, comprising: a first optical element having a first focal length; a second optical element comprising a variable focal length component having a shape that is controlled by at least one electrical input into the second optical element so as to provide a variable second focal length, the variable focal length component being located at a fixed first distance of nominally the first focal length away from a location of the first optical element along an optical path of the imaging device; an image detector comprising a photodetector array located at a fixed second distance away from the second optical element along the optical path; and a control system, wherein: the first optical element is configured to input image light from an object and to output the image light to the second optical element; the variable focal length component is configured to input the image light output from the first optical element and to output that image light to form an image of the object on the photodetector array; the imaging device is configured such that the variable second focal length provides a plurality of second focal lengths within a second focal length range, the plurality of second focal lengths provide a plurality of focusing distances within a focusing distance range of the imaging device, and each such focusing distance provides a corresponding focused image of the object on the photodetector array when the object is located at that focusing distance, wherein a magnification of the imaging device is nominally the same for each such focused image; and the control system is configured to input image data derived from the photodetector array, analyze the image data, and determine the at least one electrical input into the second optical element such that a resulting focusing distance of the imaging device provides a focused image of an object located within the focusing distance range of the imaging device.