Method of and apparatus for target tracking
Endoscope with sensor
Active auto focus system improvement
Optical displacement and contour measuring
Non-contact visual proximity sensing apparatus
Range finder Patent #: 4477168
ApplicationNo. 06/742852 filed on 06/10/1985
US Classes:356/4.04, Of degree of defocus356/624Focus
ExaminersPrimary: Hix, L. T.
Assistant: Rutledge, D.
Attorney, Agent or Firm
International ClassesG01C 3/32 (20060101)
G01C 3/00 (20060101)
AbstractThe range of a target is determined by imaging an illuminated spot on the target onto a detector surface by a focusing lens. The detector is positioned away from the focal point of the image of the illuminated spot, so that the image appears as a blurred circle. The range of the target is uniquely determined by the diameter of the blurred circle. In one embodiment the detector surface comprises a relatively large area having a narrow central area within two parallel boundaries equally spaced from a line representing the locus of the centers of the images on the detector surface. The diameter of the blurred circle can be determined by comparing the light energy received in the narrow central area of the detector with the total light energy received by the detector.