A spectrometer with a Schmidt reflector is described. The spectrometer may include a Schmidt corrector and a dispersive element as separate components. Alternatively, the Schmidt corrector and dispersive element may be combined into a single optical component. The spectrometer may further include a field-flattener lens.

A projection system can include a first modulator including a plurality of pixels in a first modulator surface, a second modulator including a plurality of pixels in a second modulator surface, and an intermediate imaging optical unit, which images the first modulator surface onto the second modulator surface, wherein the intermediate imaging optical unit includes a first lens having a convex side and wherein the convex side of the first lens is a free-form surface, which is not spherical and not rotationally symmetric and does not exhibit any mirror symmetry.

Disclosed is a novel assembly and method that enables a user to collimate a focused Cassegrain telescope. The assembly, having a secondary mirror and support baffle, comprising an axle, a bearing, and hub, enables a user to precisely rotate or freely spin a Cassegrain telescope's secondary mirror about its optical axis. Incident to freely spinning the telescope's secondary mirror, the user may peer into the telescope's eyepiece and observe a focused image that may wobble, or remain stable, dependent upon how well the telescope's mirrors are aligned. Further, the assembly's eyepiece, comprising a reticle design, enables the observer to measure the magnitude and direction of image shift incident to the secondary mirror spinning. Lastly, the assembly, comprising a radially marked collimating faceplate, and radially marked collimating knob screws, enables a user to make specific adjustments to the telescope's secondary mirror, compensating for the observed image shift, precisely collimating the telescope.

Provided is a camera lens of a catadioptric optical system consisting of two lens assemblies and one lens and having a small height, a narrow angle, and good optical properties. The camera lens includes: a first lens assembly including an object side surface having a first refractive surface and a second reflective surface in a peripheral region and a central region thereof, and an image side surface having a second refractive surface, a fifth refractive surface and a sixth refractive surface that are sequentially arranged from a peripheral region to a central region thereof; a second lens assembly including an object side surface having a third refractive surface and a fourth refractive surface that are sequentially arranged from a peripheral region to a central region, and an image side surface having a first reflective surface; and a third lens having a refractive power.

A spectrometer with a Schmidt reflector is described. The spectrometer may include a Schmidt corrector and a dispersive element as separate components. Alternatively, the Schmidt corrector and dispersive element may be combined into a single optical component. The spectrometer may further include a field-flattener lens.

A projection system includes a first optical system, a second optical system including a first optical element and a second optical element and disposed on the enlargement side of the first optical system, and a placement mechanism configured to selectively place one of the first and second optical elements on a first optical axis of the first optical system. The first optical element has a first light incident surface, a first reflection surface disposed on the enlargement side of the first light incident surface, and a first light exiting surface disposed on the enlargement side of the first reflection surface. The second optical element has a second light incident surface, a second reflection surface disposed on the enlargement side of the second light incident surface, and a second light exiting surface disposed on the enlargement side of the second reflection surface.

Provided is a camera lens of a catadioptric optical system consisting of two lens assemblies and one lens and having a small height, a narrow angle, and good optical properties. The camera lens includes: a first lens assembly including an object side surface having a first refractive surface and a second reflective surface in a peripheral region and a central region thereof, and an image side surface having a second refractive surface, a fifth refractive surface and a sixth refractive surface that are sequentially arranged from a peripheral region to a central region thereof; a second lens assembly including an object side surface having a third refractive surface and a fourth refractive surface that are sequentially arranged from a peripheral region to a central region, and an image side surface having a first reflective surface; and a third lens having a refractive power.

A projection system can include a first modulator including a plurality of pixels in a first modulator surface, a second modulator including a plurality of pixels in a second modulator surface, and an intermediate imaging optical unit, which images the first modulator surface onto the second modulator surface, wherein the intermediate imaging optical unit includes a first lens having a convex side and wherein the convex side of the first lens is a free-form surface, which is not spherical and not rotationally symmetric and does not exhibit any mirror symmetry.

A modified-Schmidt corrector lens including a first side having a curved surface configured to direct electromagnetic radiation, and a second side having a stepped surface including one or more stepped zones positioned to maintain a substantially constant thickness along a radius of the corrector lens.

A projection system includes a first optical system, a second optical system including a first optical element and a second optical element and disposed on the enlargement side of the first optical system, and a placement mechanism configured to selectively place one of the first and second optical elements on a first optical axis of the first optical system. The first optical element has a first light incident surface, a first reflection surface disposed on the enlargement side of the first light incident surface, and a first light exiting surface disposed on the enlargement side of the first reflection surface. The second optical element has a second light incident surface, a second reflection surface disposed on the enlargement side of the second light incident surface, and a second light exiting surface disposed on the enlargement side of the second reflection surface.