In some implementations, an optical device may include an aperture, one or more optical elements, an optical filter, and an optical sensor. The aperture may be configured to receive light. The one or more optical elements may be configured to diffuse the light received by the aperture, direct the diffused light to the optical filter via a folded optical path, wherein a length of the folded optical path is greater than a distance between the aperture and an input surface of the optical filter, and cause the diffused light to be distributed across the input surface of the optical filter. The optical filter may be configured to filter the diffused light distributed across the input surface of the optical filter to pass portions of the diffused light associated with one or more wavelengths to the optical sensor.

A sensing apparatus can be configured to detect an edge of a paper that is received by an automated transaction machine (ATM). The paper can move along a path located inside the ATM, the path having opposite first and second sides. The sensing apparatus can include a light emitter and a light detector on the first side of the path, with the light emitter positioned so that it can emit light across the path to the second side. The light detector can be configured to detect light from the light emitter and can emit a signal corresponding to an amount of detected light. The sensing apparatus can also include a control circuit that can control a flow of power to the light emitter, and the control circuit can also receive the signal emitted by the sensor.

A digital exposure apparatus includes a lens array, the lens array at least including a first lens unit and a second lens unit, a light transposition assembly arranged on an exit light path of the second lens unit, and the light transposition assembly being used for controlling a light exiting from the second lens unit to be transposed with respect to an exposure direction of the digital exposure apparatus. When the digital exposure apparatus is used for exposure, a light passing through the first lens unit and a light penetrating through the second lens unit are needed to expose the same position for multiple times.

Imaging systems and methods are provided for taking high-magnification photographs confined to a small physical volume. In some embodiments the system is composed of at least one lens, one or more partially reflective elements, and a sensor. The partial reflectors reflect a portion of the light back and forth between them to allow a long path length for a portion of the light from the lens to the sensor which enables a high magnification.

An all-reflective optical system is described including a concave primary mirror having a central aperture and a radius, the primary mirror having one of a parabolic, non-parabolic conical, or aspherical surface, a convex secondary mirror facing the primary mirror, the secondary mirror having an aspherical surface, where an optical axis extends from a vertex of the primary mirror to a vertex of the secondary mirror, a concave tertiary mirror arranged behind the primary mirror, the tertiary mirror having one of a parabolic, non-parabolic conical or aspherical surface, a concave quaternary mirror arranged in the central aperture of the primary mirror or behind the primary mirror, the quaternary mirror having one of a spherical, parabolic, non-parabolic conical or aspherical surface, and at least one image plane having one or more aggregated sensors, wherein the image plane is positioned at a radial distance from the optical axis that is no more than the radius of the primary mirror.

An optical pulse stretcher includes a first delay optical system including a plurality of concave toroidal mirrors; and a beam splitter including a first surface and a second surface, causing a part of pulse laser light incident on the first surface to be transmitted in a first direction and output as a first beam and another part thereof to be reflected in a second direction and enter the first delay optical system, and causing a part of pulse laser light incident on the second surface from the first delay optical system to be reflected in the first direction and output as a second beam.

A non-linear optical pumping detection apparatus and a non-linear optical absorption cross-section measurement method, which can simultaneously measure degenerate and non-degenerate two-photon absorption cross-section spectra. The measurement process is automatic, efficient and fast. The working wavelength band is from 380 nm to near infrared 1064 nm, and the non-linear performance measurement of the super-continuous wide spectra can be realized. A zoom optical system with a larger entrance pupil diameter is adopted as a weak signal acquisition lens. So the weak signal can be effectively extracted from background noise. Meanwhile, the mean square root diameter of an on-axis image point of the zoom optical system is 100 to 150 microns, the divergence angle 2α of the on-axis image point is 30.6 degrees, which well match the optical fiber coupling condition, thereby improving the coupling efficiency of the space light coupling into the optical fiber, and greatly improving the measurement sensitivity.

In an illustrative configuration, a method for monitoring air quality is disclosed. The method includes accepting analyte gas into a cell and reflecting light rays into the analyte gas repeatedly across the cell into at least one sensor. The light scattered by particulate matter in the analyte gas and amount of spectra-absorption due to presence of a gaseous chemical is then measured. Based on the determined amount of spectra-absorption and the measured scattered light the gaseous chemical is then measured.

An optical module includes a fast-axis mirror that scans a laser beam along a fast-axis, a magnification mirror set formed by three discrete mirrors shaped to magnify the laser beam as it is scanned along the fast-axis and reflect the laser beam after magnification toward a slow-axis mirror that scans the laser beam along the slow-axis, and an Offner mirror relay that receives the laser beam as it is scanned along the slow-axis and reflects the laser beam out an exit aperture. The laser beam as output from the exit aperture is received at an input diffractive grating of a diffractive waveguide, with a user's eye being positioned adjacent an output diffractive grating of the waveguide such that the user's eye views ambient light entering the waveguide from objects within the user's field of view as well as light from the laser beam as it exits the output diffractive grating.

In an illustrative configuration, a method for monitoring air quality is disclosed. The method includes accepting analyte gas into a cell and reflecting light rays into the analyte gas repeatedly across the cell into at least one sensor. The light scattered by particulate matter in the analyte gas and amount of spectra-absorption due to presence of a gaseous chemical is then measured. Based on the determined amount of spectra-absorption and the measured scattered light the gaseous chemical is then measured.