Multi lens for efficient collection of light at varying distances
AssigneeImatronic Limited
InventorGraham S. B. Street
Life of this patent
Estimating the term…
Abstract
Optical distance measuring apparatus has a focusing lens (16) directing light reflected from a target toward a detector (18), The lens has discrete or continuous zones each associated with a target distance. The area of the lens zones increases with an increase in associated target distance so as to compensate for a reduction in intensity according to the inverse square law.
Claims9
Optical apparatus comprising a light beam source;
- light detector means and convergent optical means for directing light returned from a target onto the detector means, characterised in that the convergent optical means comprises a plurality of zonal elements each having an associated target distance at which returned light is directed optimally onto the detector means, the light gathering capability of the respective elements varying as between the elements with an increase in associated target distance so as to compensate for the reduction in the intensity of reflected light as a function of said distance.
Apparatus according to any one of the preceding claims, wherein the light beam source is adapted to produce a light beam along a first axis and wherein the zonal elements comprise respective zones of a first refractive surface, the converging optical means including a second refractive surface, the first refractive surface being rotationally symmetric about said first axis and said second refractive surface being rotationally symmetric about a second axis parallel to and spaced from said first axis.
Dependencies are inferred from the claim text.