Focus detecting apparatus in which matching with the image performance of an objective lens is achieved

Claim 1

An apparatus for detecting the focus-adjusted state of an objective lens, comprising: field lens means, having a plurality of field lenses, disposed near a predetermined imaging plane of the objective lens; a plurality of light intensity distribution forming means for forming light intensity distributions relating to an object from a light flux passed through said objective lens and said field lens means, said light intensity distributions moving relative to each other; light receiving means for receiving said light intensity distributions and forming a signal indicative of the focus-adjusted state of said objective lens based on the relative positional relation between said light intensity distributions; and masking means disposed near said predetermined imaging plane for selectively forming an opening at any one of a plurality of different locations in said masking means.

Claim 2

An apparatus for detecting the focus-adjusted state of an objective lens, comprising: field lens means, having a plurality of field lenses, disposed near a predetermined imaging plane of the objective lens; a plurality of light intensity distribution forming means for forming light intensity distributions relating to an object from a light flux passed through said objective lens and said field lens means, said light intensity distributions moving relative to each other; light receiving means for receiving said light intensity distributions and forming a signal indicative of the focus-adjusted state of said objective lens based on the relative positional relation between said light intensity distributions; and masking means disposed near said predetermined imaging plane for selectively forming an opening at any one of a plurality of different locations in said masking means.

Claim 4

An apparatus for detecting a focus-adjusted state of an objective lens having an optic axis, comprising: field lens means disposed near a predetermined imaging plane of the objective lens; a plurality of light intensity distribution forming means for forming light intensity distributions relating to an object from a light flux passed through said objective lens and said field lens means, said light intensity distributions moving relative to each other; light receiving means for receiving said light intensity distributions and forming a signal indicative of the focus-adjusted state of said objective lens based on the relative positional relation between said light intensity distributions; masking means disposed near said predetermined imaging plane for masking said light receiving means except for the light receiving areas thereof and having openings at a plurality of different locations therein; and stop means provided with a plurality of sets of stop openings for separating a light flux entering said tight intensity distribution forming means at the pupil position of said objective lens and disposed between said field lens means and said light receiving means; and the stop openings which form the set for receiving the light flux passed through an off-axis opening of said masking means being all determined so as to be symmetrical with respect to an imaginary plane passing through the center of the off-axis opening of said masking means and containing the optic axis of said objective lens so that the influence of the abberations of said objective lens becomes uniform, said plurality of sets of stop openings including an on-axis set of stop openings disposed parallel to an off-axis set of stop openings wherein said light receiving means comprises at least one pair of line sensors, and wherein said light receiving means comprises at least one pair of line sensors, and wherein said intensity distribution forming means comprises a number of pairs of lenses, the number of pairs of said light intensity distribution forming means being greater than the number of pairs of said line sensors.

Claim 5

An apparatus for detecting a focus-adjusted state of an objective lens having an optic axis, comprising: field lens means disposed near a predetermined imaging plane of the objective lens; a plurality of light intensity distribution forming means for forming light intensity distributions relating to an object from a light flux passed through said objective lens and said field lens means, said light intensity distributions moving relative to each other; light receiving means for receiving said light intensity distributions and forming a signal indicative of the focus-adjusted state of said objective lens based on the relative positional relation between said light intensity distributions; masking means disposed near said predetermined imaging plane for masking said light receiving means except for the light receiving areas thereof and having openings at a plurality of different locations therein; and stop means provided with a plurality of sets of stop openings for separating a light flux entering said tight intensity distribution forming means at the pupil position of said objective lens and disposed between said field lens means and said light receiving means; and the stop openings which form the set for receiving the light flux passed through an off-axis opening of said masking means being all determined so as to be symmetrical with respect to an imaginary plane passing through the center of the off-axis opening of said masking means and containing the optic axis of said objective lens so that the influence of the abberations of said objective lens becomes uniform, said plurality of sets of stop openings including an on-axis set of stop openings disposed parallel to an off-axis set of stop openings wherein said light receiving means comprises at least one pair of line sensors, and wherein said light receiving means comprises at least one pair of line sensors, and wherein said intensity distribution forming means comprises a number of pairs of lenses, the number of pairs of said light intensity distribution forming means being greater than the number of pairs of said line sensors.

Claim 6

An apparatus for detecting the focus-adjusted state of an objective lens, comprising: field lens means disposed near a predetermined imaging plane of the objective lens; a plurality of light intensity distribution forming means for forming light intensity distributions relating to an object from a light flux passing through the objective lens and said field lens means, the light intensity distributions moving relative to each other; a plurality of pairs of line sensors for receiving the light intensity distributions, each pair of said line sensors forming a signal indicative of the focus-adjusting state of the objective lens based on the relative positional relation between the light intensity distributions; and masking means disposed near the predetermined imaging plane for selectively forming an opening at a predetermined location in said masking means.

Claim 7

An apparatus for detecting the focus-adjusted state of an objective lens, comprising: field lens means disposed near a predetermined imaging plane of the objective lens; a plurality of light intensity distribution forming means for forming light intensity distributions relating to an object from a light flux passing through the objective lens and said field lens means, the light intensity distributions moving relative to each other; a plurality of pairs of line sensors for receiving the light intensity distributions, each pair of said line sensors forming a signal indicative of the focus-adjusting state of the objective lens based on the relative positional relation between the light intensity distributions; and masking means disposed near the predetermined imaging plane for selectively forming an opening at a predetermined location in said masking means.