COMPACT RANGEFINDING DEVICE

• US 3,680,946 A
• Filed: 06/04/1969
• Issued: 08/01/1972
• Est. Priority Date: 06/04/1969
• Status: Expired due to Term

• Current Assignee: Alfred H. Bellows
• Original Assignee: Alfred H. Bellows
• Inventors: Bellows, Alfred H.
• Primary Examiner(s): Schonberg, David
• Assistant Examiner(s): Kusmer, Toby H.
• Application Number:
  US04/830,402
• Time in Patent Office: 1,154 Days
• Field of Search: 350/102,28-30,36,201,55 356/12-14
• US Class Current: 359/505
• CPC Class Codes: G02B 23/14 Viewfinders for photographic apparatus G03B13/02

Abstract

A compact viewing device permits observation of a field of view and superimposes thereon a virtual image of a reticle. The device includes a concave light reflecting surface transecting a line of sight extending from an observer into the field of view and a second mirror transecting the line of sight, the distance along the line between the mirrors being less than the focal length of the concave mirror. The reticle is positioned so that the second mirror directs light from the reticle to the concave mirror along a path which may substantially equal the focal length of the concave mirror. The concave mirror then focuses and redirects the light to the observer to form the virtual image of the reticle. The viewing devices are usable in pairs to form a binocular viewfinder producing a composite virtual image resulting from two distinct left and right eye images. The reticles are movable for causing variation in the apparent position in the field of view of the composite image.

Claims

1. A rangefinder comprising:

a left eyepiece forming entrance and exit windows spaced along a left line of sight;

a right eyepiece forming entrance and exit windows spaced along a right line of sight;

a partially reflecting, partially transparent spherical mirror within each of said eyepieces, said spherical mirrors being concave toward said exit windows;

a partially reflecting, partially transparent planar mirror within each of said eyepieces, adjacent said spherical mirror and between said spherical mirror and said exit window, said planar mirrors positioned to reflect light emanating from a location between said left and said right eyepieces into said concave spherical mirrors;

a left eye reticle between said left and right eyepieces and proximate said left eyepiece;

a right eye reticle, between said left and right eyepieces and proximate said right eyepieces, said left and right eye reticles representing left and right eye perspective views, respectively, of an indicia whose image appears superimposed on the field of view seen through said eyepiece;

light means, between said reticles, for illuminating said reticles in a manner that directs the illumination into the respective eyepieces;

means for moving said reticles in a manner that changes the apparent location of their images in the field seen through said eyepieces in such a way that an observer looking through the eyepieces fuses the images of the indicia and perceives the indicia to advance and retreat according to the operation of said moving means.

2. The rangefinder described in claim 1, further comprising:

a transparent plate with a concave surface for supporting said partially reflecting, partially transparent spherical mirror;

a first transparent wedge with one planar surface having thereon said partially transparent, partially reflective planar mirror and one convex spherical surface, conforming to said concave surface, and a receiving window in the base of said transparent wedge for admitting light from said light means into said first transparent wedge; and

a second transparent wedge with two planar surfaces, said first transparent wedge joined to said transparent plate with said convex surface nesting in said concave surface and said second transparent wedge joined to said first transparent wedge, the apex of one proximate the base of the other.