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US 5,214,538 AGranted
Optical apparatus
AssigneeKeymed (Medical & Industrial Equipment) Ltd.
InventorDaniel R. Lobb
Life of this patent
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AssigneeKeymed (Medical & Industrial Equipment) Ltd.
InventorDaniel R. Lobb
Estimating the term…
A laser beam is projected through the optical system of an endoscope and scanned in raster fashion by means of a scanning head at a proximal end of the endoscope tube. The beam is projected from a distal end of the endoscope tube so as to be scanned over an object. Light reflected from the object is detected and used to form a television image. The range of the object is measurable in a ranging mode of the apparatus in which the depth of focus of the projected laser beam is reduced using a zoom lens at the distal end of the endoscope and the focus distance of the projected beam varied until an in-focus position is detected by analysis of the reflected light. Detection of the in-focus position relies on characteristics of laser speckle, a selected portion of the object being scanned in ranging mode to detect maximum modulation in the speckle pattern which occurs when the focus distance corresponds to the range of the object. Range and object size information may then be included in a television image of the object.
An optical assembly comprising an objective lens and a field lens which is movable relative to the objective lens between a first position adjacent the objective lens and a second position spaced from the objective lens, the field lens and objective lens in combination defining a focal plane which is at the same location relative to the objective lens for both first and second positions of the field lens and wherein the field lens passes through the focal plane in moving between the first and second positions.
Dependencies are inferred from the claim text.