Detector balance apparatus and method employing selective masks

Claim 1

Apparatus for adjusting the outputs of a first and a second pair of radiation detectors receiving radiation from a remote object through a lens in first and second paths respectively comprising: positioning means mounting the first pair of detectors to receive a first image of the exit pupil of the lens and mounting the second pair of detectors to receive a second image of the exit pupil of the lens, the position of the first pair of detectors in the first image being displaced from the position of the second pair of detectors in the second image; first adjustable means positioned to be moveable into the first path and operable to block a portion of the radiation received by a first detector in the first pair while not blocking a portion of the radiation received by either detector in the second pair; and second adjustable means positioned to be moveable into the second path and operable to block a portion of the radiation received by a first detector in the second pair while not blocking a portion of the radiation received by either detector in the first pair.

Claim 6

The method of balancing the outputs of a first pair of radiation responsive detectors mounted to receive a first image of the exit pupil of a focus lens and balancing the outputs of a second pair of radiation responsive detectors mounted to receive a second image to the exit pupil of the focus lens comprising the steps of: displacing the first pair of detectors in the first image with respect to the second pair of detectors in the second image; exposing the detectors in the first and second pairs to equal amounts of radiation; placing first opaque means between the focus lens and the detectors so as to cast a shadow on a portion of the detectors in the first pair but not on the detectors in the second pair; placing second opaque means between the focus lens and the detectors so as to cast a shadow on a portion of each of the detectors in the second pair but not on the detectors in the first pair; and moving the first and second opaque means to first and second positions respectively where the outputs of the detectors in the first and second pairs are substantially equal.

Claim 7

The method of balancing the outputs of a first pair of radiation responsive detectors mounted to receive a first image of the exit pupil of a focus lens and balancing the outputs of a second pair of radiation responsive detectors mounted to receive a second image to the exit pupil of the focus lens comprising the steps of: displacing the first pair of detectors in the first image with respect to the second pair of detectors in the second image; exposing the detectors in the first and second pairs to equal amounts of radiation; placing first opaque means between the focus lens and the detectors so as to cast a shadow on a portion of the detectors in the first pair but not on the detectors in the second pair; placing second opaque means between the focus lens and the detectors so as to cast a shadow on a portion of each of the detectors in the second pair but not on the detectors in the first pair; and moving the first and second opaque means to first and second positions respectively where the outputs of the detectors in the first and second pairs are substantially equal.