Automatic focusing system

Claim 3

The system recited in claim 1 wherein said second beam splitter is a 50-50 beam splitter, said system further comprising: an optical microscope, said microscope being positioned relative to said 50.50 beam splitter to observe images of said first and said second masks formed by light reflected from said masks and projected through said beam splitter into said optical microscope to form superimposed images of said first and second masks so that an observer can align said masks by moving one mask relative to the other until the mask apertures coincide in the superimposed images.

Claim 4

An automatic focusing system for optical apparatus comprising: an adjustable objective lens producing an object image, a first beam splitter for projecting said image to an actual image plane, utilization means positioned at a desired image plane which is coincident with said actual image plane when said object image is in focus for producing an electrical output representing selected optical characteristics of said image, a second beam splitter receiving the image projected from said first beam splitter, said second beam splitter projecting said image to first and second parfocal image planes, first and second light sensing devices for receiving light from in front of said first parfocal image plane and behind said second parfocal image plane respectively, said light sensing devices respectively producing first and second electrical signals representing the position of said actual image plane with respect to said desired image plane, and means responsive to said first and second electrical signals for automatically positioning said adjustable objective lens to bring said object image into focus at said desired image plane.

Claim 5

An automatic focusing system for optical apparatus comprising: an adjustable objective lens producing an object image, a first beam splitter for projecting said image to an actual image plane, utilization means positioned at a desired image plane which is coincident with said actual image plane when said object image is in focus for producing an electrical output representing selected optical characteristics of said image, a second beam splitter receiving the image projected from said first beam splitter, said second beam splitter projecting said image to first and second parfocal image planes, first and second light sensing devices for receiving light from in front of said first parfocal image plane and behind said second parfocal image plane respectively, said light sensing devices respectively producing first and second electrical signals representing the position of said actual image plane with respect to said desired image plane, and means responsive to said first and second electrical signals for automatically positioning said adjustable objective lens to bring said object image into focus at said desired image plane.

Claim 6

The system recited in claim 3 wherein said first and second light sensing devices are separate devices which simultaneously produce said first and second electrical signals.

Claim 7

The system recited in claim 3 wherein said second beam splitter is a partially reflecting surface that transmits a portion of the light incident thereon and reflects a portion of the light incident thereon.

Claim 8

The system recited in claim 3 wherein said means responsive to said first and second electrical signals comprises a differentiator, said electrical signals from said light sensing devices being applied to said differentiator to produce differentiated electrical signals, a comparator for comparing said differentiated electrical signals, and means responsive to the output of said comparator for moving said objective lens.

Claim 9

The system recited in claim 3 further comprising means disposed between said first and second beam splitters for optically scanning said image across said first and second light sensing devices.

Claim 12

An automatic focusing system for optical apparatus comprising: an adjustable objective lens producing an object image, a first beam splitter for projecting said image to an actual image plane, utilization means positioned at a desired image plane which is coincident with said actual image plane when said object image is in focus for producing an electrical output representing selected optical characteristics of said image, a second beam splitter receiving the image projected from said first beam splitter, said second beam splitter projecting said image to first and second parfocal image planes, first and second light sensing devices for receiving light from in front of said first parfocal image plane and behind said second parfocal image plane respectively, said light sensing devices respectively producing first and second electrical signals representing the position of said actual image plane with respect to said desired image plane, means responsive to said first and second electrical signals for automatically positioning said adjustable objective lens to bring said object image into focus at said desired image plane, a differentiator, said electrical signals from said light sensing devices being applied to said differentiator to produce differentiated electrical signals, a comparator for comparing said differentiated electrical signals, the output of said comparator being applied to said means for automatically positioning said adjustable objective lens, and a stepping motor for moving said objective lens in either direction along the optical axis of said lens, said comparator being connected to drive said stepping motor in a first direction when said dirst electrical signal is greater than said second electrical signal and in the opposite direction when said second electrical signal is greater than said first electrical signal, and further including first and second apertured means associated with the first and second light sensing devices, and means for adjusting the relative positions between said apertured means so that the same portion of an image is projected out to said first and second light sensing devices.

Claim 13

An automatic focusing system for optical apparatus comprising: an adjustable objective lens producing an object image, a first beam splitter for projecting said image to an actual image plane, utilization means positioned at a desired image plane which is coincident with said actual image plane when said object image is in focus for producing an electrical output representing selected optical characteristics of said image, a second beam splitter receiving the image projected from said first beam splitter, said second beam splitter projecting said image to first and second parfocal image planes, first and second light sensing devices for receiving light from in front of said first parfocal image plane and behind said second parfocal image plane respectively, said light sensing devices respectively producing first and second electrical signals representing the position of said actual image plane with respect to said desired image plane, means responsive to said first and second electrical signals for automatically positioning said adjustable objective lens to bring said object image into focus at said desired image plane, a differentiator, said electrical signals from said light sensing devices being applied to said differentiator to produce differentiated electrical signals, a comparator for comparing said differentiated electrical signals, the output of said comparator being applied to said means for automatically positioning said adjustable objective lens, and a stepping motor for moving said objective lens in either direction along the optical axis of said lens, said comparator being connected to drive said stepping motor in a first direction when said dirst electrical signal is greater than said second electrical signal and in the opposite direction when said second electrical signal is greater than said first electrical signal, and further including first and second apertured means associated with the first and second light sensing devices, and means for adjusting the relative positions between said apertured means so that the same portion of an image is projected out to said first and second light sensing devices.