Methods and devices for expanding a laser beam are provided. In one aspect, a device includes a telescope arrangement having two spherical folding mirrors for expanding an incident collimated laser beam with a lens arranged in the divergent beam path downstream of the telescopic arrangement. The two spherical folding mirrors in the beam path are a first, convex-curved spherical folding mirror and a second, concave-curved spherical folding mirror, respectively. The lens has a spherical lens face for collimating the expanded laser beam from the telescope arrangement. The laser beam can be an ultraviolet (UV) laser beam.

There is provided an optical arrangement comprising a digital micromirror device having a plurality of individually adjustable mirrors, a mirror pair formed from a convex mirror and a concave mirror having a common centre of curvature, the concave mirror having a greater radius than the convex mirror, characterised in that a collimated space is immediately adjacent the convex mirror, and the concave mirror is offset from the convex mirror so as to be capable of forming an image at an effective focal length of the mirror pair. The convex mirror and the concave mirror have radii substantially in the proportion 2.5:1, the concave mirror having the greater radius. A confocal microscope using such an arrangement is also provided.

A projection apparatus includes an image-producing element and projection optics. The image-producing element produces at least one image, and the projection optics has free-form areas for magnifying and reflecting the image toward an viewer for observation. The projection optics includes at least a first mirror and a second mirror, the image is reflected by the first mirror and the second mirror in succession, no deflection mirror is disposed between the viewer and the second mirror, and the first mirror and the second mirror are in the form of a non-rotationally symmetrical system.

An optical projection unit includes first and second optical element modules. The first optical element module includes a first housing unit and a first optical element received within the first housing unit and having an optically used first region defining a first optical axis. The second optical element module is located adjacent to the first optical element module and includes a second optical element which defines a second optical axis of the optical projection unit. The first housing unit has a central first housing axis and an outer wall extending in a circumferential direction about the first housing axis. The first optical axis is laterally offset and/or inclined with respect to the first housing axis. The first housing axis is substantially collinear with the second optical axis.

Provided is an optical system having a configuration capable of attaining a large light-gathering power while producing a maximum light-gathering power easily and inexpensively with a minimum material. An offset optical system according to the present invention comprises: a primary mirror composed of at least part of one of two optical element halves obtained by dividing an optical element having a concave shape curved only in one direction, in an intermediate position of a length along a curvature thereof, wherein the optical element is configured to reflect and focus light from an object, into a linear focus; a sub-mirror disposed between the primary mirror and the linear focus and configured to transmit or reflect light reflected by the primary mirror, thereby focusing the light into a point focus; wherein, when: a direction tangent to the curvature in the intermediate position of the optical element is defined as an x-axis; a direction which is perpendicular to the x-axis and in which the object is located is defined as a y-axis; and a direction orthogonal to the x-axis and the y-axis is defined as a z-axis, the sub-mirror is offset parallel to the x-axis by a given distance toward an edge of the primary mirror located distal to the y-axis.

An optical system has a reduction conjugate point on a reduction side and a magnification conjugate point on a magnification side, and has an intermediate imaging position conjugate with each of the reduction conjugate point and the magnification conjugate point inside. The optical system includes: a first sub-optical system including a plurality of lenses; and a second sub-optical system including a plurality of optical surfaces. A magnification conjugate plane including the magnification conjugate point is positioned in a direction of the first sub-optical system, from a viewpoint of the second sub-optical system. The plurality of optical surfaces include: a first transmitting surface; a second transmitting surface; a first reflecting surface; and a second reflecting surface. A first effective area through which a light flux passes in the first transmitting surface and a second effective area through which the light flux passes in the second transmitting surface do not overlap.