US 5,963,366 A · Focus detection unit and microscope using the focus detection unit

Abstract

A focus detection unit including an optical system employing an image sandwiching method is disclosed. In the focus detection unit, a double slit mask (12) forming double sight lines is disposed on the optical axis of a lamp 10 while a single slit mask (16) forming an single sight line is disposed on the optical axis of a lamp (14). A triangular pole prism 18 is provided, consisting of first and second side surfaces, which together constitutes an edge, and a plane opposing the edge. The prism (18) is disposed such that the double and single sight line are able to irradiate the first and second side surfaces. The prism reflects the incoming lines toward a plane before the right-angle edge. Before the edge of the prism (18), a projection lens (20) is provided for forming images of the double and single sight lines which have been reflected by the prism (18) and separated by a mask (22), at a both aiming line imaging position 100. The images are projected onto a workpiece.

Claims12

Dependent claims

A focus detection unit for focusing by forming images of double sight lines and an image of a single sight line on an image surface of an optical system of a microscope, projecting the images onto a workpiece, and adjusting the images such that the image of the single sight line is sandwiched by the images of the double sight lines, comprising:

a first light source;
a double slit mask provided on an optical axis of the first light source, for forming the double sight lines;
a second light source;
a single slit mask provided on an optical axis of the second light source, for forming the single sight line;
a triangular pole shaped prism having a first side surface and a second side surface together constituting an edge of a predetermined angle, and a plane opposing to the edge, for reflecting the double sight lines irradiating the first side surface and the single sight line irradiating the second side surface, toward an area before the edge, and
a projection lens provided before the edge of the prism, for projecting the images of the double sight lines and the image of the single sight line onto the workpiece.

3 more elements

A microscope including a focus detection unit for focusing by forming images of double sight lines and an image of a single sight line on an image surface of an optical system of a microscope, projecting the images onto a workpiece, and adjusting the images such that the image of the single sight line image is sandwiched by the image of the double sight lines, comprising:

a first light source;
a double slit mask provided on an optical axis of the first light source, for forming the double sight lines;
a second light source;
a single slit mask provided on an optical axis of the second light source, for forming the single sight line;
a triangular pole shaped prism having a first side surface and a second side surface together constituting an edge of a predetermined angle, and a plane opposing to the edge, for reflecting the double sight lines irradiating the first side surface and the single sight line irradiating the second side surface, toward an area before the edge;
and
a projection lens provided before the edge of the prism, for projecting the images of the double sight lines and the image of the single sight line onto the workpiece;
a first half reflection mirror whose center area is a full reflection mirror, for reflecting at predetermined angle, the images of the double sight lines and the image of the single sight line formed by the projection lens;
a second half reflection mirror for half-reflecting the images of the double sight lines and the image of the single sight line reflected by the first half reflection mirror;
an objective for forming the images of the double sight lines and the image of the single sight line formed by the projection lens and half-reflected by the second half reflection mirror, on an image surface of the workpiece;
a third light source provided behind the first half reflection mirror;
wherein
light from the third light source partly passes through the first half reflection mirror,
only that light from the third light source that has passed through the first half reflection mirror to be half-reflected by the second half reflection mirror and to reach, via the objective, to the image surface of the workpiece, and
a dark field is formed at a middle of a bright field on the image surface of the workpiece so that the images of the double sight lines and the image of the single sight line are formed therein.

12 more elements

Dependencies are inferred from the claim text.

Focus detection unit and microscope using the focus detection unit

Life of this patent

Focus detection unit and microscope using the focus detection unit

Life of this patent

Abstract

Claims12