Optical measuring apparatus using measuring and comparison light beams

Claim 2

In an optical measuring apparatus comprising a light source, a photoelectric receiver and optical means, including light reflector of a given size and an aperture diaphragm, for defining a measuring light beam in a path between the source and the receiver, said light beam traversing said diaphragm and, along a portion of said path, said light beam being directed toward and returned from said reflector along a common way, the improvement comprising: said optical means imaging said aperture diaphragm in the plane of said reflector and in a size larger than the size of said reflector.

Claim 3

In an apparatus as set forth in claim 1, including rotating disc diaphragm means for chopping light beams, said light path traversing said disc diaphragm to be chopped thereby with the receiver on one side of the disc diaphragm means and the source on the other side thereof; and wherein said optical means includes a partially transmissive mirror between said source and said disc diaphragm to divide from said beam a comparison beam, said optical means directing said comparison beam along a second path to the receiver, said two beams striking the receiver from at least approximately the same direction, said second path traversing said disc diaphragm means in a different area thereof so that the comparison beam is chopped differently than is said measuring beam.

Claim 4

In an apparatus as set forth in claim 2, wherein said optical means includes a second partially transmissive mirror means positioned on said one side of said disc diaphragm means, both of said path including said second mirror means, the arrangement being such that both beams strike the receiver along a common axis.

Claim 5

In an apparatus as set forth in claim 3, wherein said optical means includes an optical condenser system between said source and said disc diaphragm means, stop diaphragm means having an opening through which said measuring beam passes, said stop diaphragm means being positioned between said system and said disc diaphragm mEans, said opening being only sufficiently large to pass radiation from the uniformly illuminated central portions of said source, said aperture diaphragm being between said source and said stop diaphragm means.

Claim 6

In an apparatus as set forth in claim 4, wherein said condenser system includes a pair of condenser lenses between which said measuring beam comprises parallel light rays, said aperture diaphragm being positioned between said lenses, said mirror between said source and said disc diaphragm means being between said diaphragm means and the one of said lenses which is closes to said disc diaphragm; and said optical means includes a micro-objective positioned in the path of the measuring beam between said one lens and said reflector, and a front lens between said micro-objective and said reflector.

Claim 7

In an apparatus as set forth in claim 5, wherein said disc diaphragm means has two rows of openings therethrough, said rows being at different radial distances from the axis of rotation thereof, said measuring beam being aligned with one row and said comparison beam being aligned with the other row, along said comparison beam said optical means sequentially comprising, commencing with said partially transmissive mirror between said source and said disc, a deflecting mirror, a third condenser lens, a second micro-objective, a third partially transmissive mirror, a concave mirror and said second partially transmissive mirror, said second transmissive mirror being inclined at an angle that bisects the angle between the axis of the measuring beam and the axis of the comparison beam.

Claim 8

In an apparatus as set forth in claim 2, wherein said partially transmissive mirror is inclined at an angle of 45* to the axis of the beam from the source thereby splitting said beam from the source into a reflected beam and a transmitted beam, said optical means including a reflective mirror in the path of said reflected beam and two reflective mirrors in the path of said transmitted beam, said mirrors being so positioned at the two beams after leaving the last of said mirrors are parallel to each other and proceeding in the same general direction, said disc diaphragm means being positioned to intersect and chop said two parallel beams, said optical means on said one side of said disc diaphragm means including two additional partially transmissive mirrors and a roof prism, one of said additional mirrors being positioned in one of said parallel paths and inclined to deflect the beam in the one path generally toward the other path, the other of said additional mirrors being positioned in the other of said parallel paths and inclined to deflect the beam in the other path generally toward said one path, said roof prism being positioned to intercept the latter two deflected beams and direct both toward said receiver.