Automatic focus sensor and control

Claim 2

Apparatus to detect and signal the deviation from optimum focus of an optical system image with respect to a predetermined plane, comprising the combination of: a. transfer means, optically coupled to the predetermined plane for transferring the optical image thereat to a remote transfer plane; b. defocusing means, including a rotating disc of transparent material of variable wall thickness in a preordered pattern, for cyclically modifying the focus of the image at the transfer plane to amplitude modulate the signal representing the optical image and to generate an index signal calibrated to represent actual focus of the optical system; c. spatial filtering means interposed in the optical path in the vicinity of the transfer plane, including an interposed element of opacity varying in a preselected pattern, for transmitting spatial frequency components of the optical image corresponding to the preselected pattern wherein said spatial filtering means is a transparent disc rotatable about an axis central thereto, and wherein said preselected pattern of opacity is arranged to be uniform radially and to vary angularly about the face of said disc; d. sensing means optically coupled to receive the image at the transfer plane and operable in response to the light signals therefrom, to derive from the impinging signals an output signal corresponding to optimum focus; and e. error generating means coupled to said defocusing means and said sensing means and operable in response to index and output signals therefrom to produce an error signal representing the direction and magnitude of the deviation from optimum focus of the image at the predetermined plane.

Claim 3

The apparatus of claim 1, above, wherein said rotatable disc wall thickness varies by incremental amounts.

Claim 4

The apparatus of claim 2, above, wherein said rotatable disc wall thickness is uniform in the radial direction and varies continuously according to a preordered pattern in the angular direction.

Claim 5

The apparatus of claim 2, above, wherein said rotatable disc wall thickness varies in a limited angular band and where said wall thickness increases to a predetermined maximum and abruptly decreases to a predetermined minimum.

Claim 6

The apparatus of claim 2, above, wherein said rotatable disc wall thickness varies in linear fashion from minimum to maximum thickness.

Claim 7

Apparatus to detect and signal the deviation from optimum focus of an optical system image with respect to a predetermined plane, comprising the combination of: a. transfer means, optically coupled to the predetermined plane for transferring the optical image thereat to a remote transfer plane; b. defocusing means, including a rotating disc of transparent material of variable wall thickness in a preordered pattern, for cyclically modifying the focus of the image at the transfer plane to amplitude modulate the signal representing the optical image and to generate an index signal calibrated to represent actual focus of the optical system; c. spatial filtering means interposed in the optical path in the vicinity of the transfer plane including an interposed element of opacity varying in a preselected pattern for transmitting spatial frequency components of the optical image corresponding to the preselected pattern, wherein said defocusing and spatial filtering means comprise an axially rotatable transparent drum having a peripheral rim and an end, optically coupled to said transfer means to receive light rays from the image through a portion of said end, said transfer plane coinciding with a portion of said peripheral rim, said defocusing means being positioned on said end, and said spatial filtering means being superimposed on said rim; d. sensing means optically coupled to receive the image at the transfer plane and operable in response to the light signals therefrom, to derive from the impinging signals an output signal corresponding to optimum focus; and e. error generating means coupled to said defocusing means and said sensing means and operable in response to index and output signals therefrom to produce an error signal representing the direction and magnitude of the deviation from optimum focus of the image at the predetermined plane.

Claim 8

Apparatus to detect and signal the deviation from optimum focus of an optical system image with respect to a predetermined plane, comprising the combination of: a. transfer means, optically coupled to the predetermined plane for transferring the optical image thereat to a remote transfer plane; b. defocusing means, including a rotating disc of transparent material of variable wall thickness in a preordered pattern, for cyclically modifying the focus of the image at the transfer plane to amplitude modulate the signal representing the optical image and to generate an index signal calibrated to represent actual focus of the optical system; c. spatial filtering means interposed in the optical path in the vicinity of the transfer plane including an interposed element of opacity varying in a preselected pattern for transmitting spatial frequency components of the optical image corresponding to the preselected pattern, wherein said defocusing and spatial filtering means comprise an axially rotatable transparent drum having a peripheral rim and an end, optically coupled to said transfer means to receive light rays from the image through a portion of said end, said transfer plane coinciding with a portion of said peripheral rim, said defocusing means being positioned on said end, and said spatial filtering means being superimposed on said rim; d. sensing means optically coupled to receive the image at the transfer plane and operable in response to the light signals therefrom, to derive from the impinging signals an output signal corresponding to optimum focus; and e. error generating means coupled to said defocusing means and said sensing means and operable in response to index and output signals therefrom to produce an error signal representing the direction and magnitude of the deviation from optimum focus of the image at the predetermined plane.

Claim 9

The apparatus of claim 6, above, wherein said defocusing means include said drum end having variable wall thickness in a preordered pattern.

Claim 10

The apparatus of claim 7, above, wherein said end wall thickness varies by incremental amounts.

Claim 11

The apparatus of claim 8, above, wherein said end wall thickness is uniform in the radial direction and varies continuously according to a preordered pattern in the angular direction.

Claim 12

The apparatus of claim 8, wherein said end wall thickness varies in a limited angular band and where said wall thickness increases to a predetermined maximum and abruptly decreases to a predetermined minimum.

Claim 13

The apparatus of claim 8, above wherein said end wall thickness varies in linear fashion from minimum to maximum thickness.

Claim 14

The apparatus of claim 6, above, wherein said spatial filter means includes a preordered distribution of opacity on said peripheral rim.

Claim 15

The apparatus of claim 12, above, wherein said preordered distribution of opacity is a sinusoid.