Provided is an optical element that suppresses ghosts where an absorbing polarizer having a curved surface portion is applied to an image display device formed of a reciprocation optical system. Further provided are a virtual reality display device, an electronic viewfinder, and a method of producing a polarizer. The optical element includes absorbing polarizers A and B, polarizer A having a curved surface portion, where a position X being of a surface of the polarizer A on a side of and closest to the side of polarizer B, a position Y being of a surface of the polarizer B on a side of polarizer A, closest to the position X, and a straight line L passing through the positions X and Y is drawn, a position Z is on the straight line L and beyond the position X when it the position X is observed from position Y.

A pulse width expansion apparatus according to an aspect of the present disclosure includes a polarization beam splitter and a transfer optical system. The transfer optical system includes ¼-wavelength and reflection mirror pairs. The ¼-wavelength mirror pair include first and second ¼-wavelength mirrors. The first ¼-wavelength mirror provides ¼-wavelength phase shift and reflects a pulse laser beam. The second ¼-wavelength mirror provides ¼-wavelength phase shift and reflects the pulse laser beam reflected by the first ¼-wavelength mirror. The reflection mirror pair are disposed on an optical path before and after or between the ¼-wavelength mirror pair. The transfer optical system transfers an image of an input pulse laser beam on the polarization beam splitter to the optical path between the ¼-wavelength mirror pair at one-to-one magnification as a first transfer image and transfers the first transfer image to the polarization beam splitter at one-to-one magnification as a second transfer image.

An electronic device includes a lens assembly that receives external light, which is used by a camera module to capture a still image and/or a moving picture, in a first direction, a housing forming an outer portion of the camera module, a first support disposed inside the housing and disposed in a second direction away from the lens assembly, wherein the second direction is perpendicular to the first direction; and a second support including at least a portion protruding in the second direction while surrounding the lens assembly, wherein the first support and the second support are disposed in the second direction away from the lens assembly.

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 telescope may include an array of optical lenslets in a common plane, and optical waveguides extending from respective optical lenslets and each having a common optical path delay. Further, at least one optical star coupler may be downstream from the optical waveguides, and an optical detector may be downstream from the at least one optical star coupler and having an optical image formed thereon.

A system and method for extending the path length of an electromagnetic wave signal traveling between apertures is disclosed. One such system may comprise N arrays having M.sub.1 through M.sub.N apertures, respectively, wherein N≥2, M.sub.1≥2, and each of M.sub.2 through M.sub.N≥1, a substantial number of the M.sub.1 apertures in a first array is configured to send the electromagnetic wave signal to a substantial number of the M.sub.2 apertures in a second array through the M.sub.N apertures in a N-th array, the substantial number of the M.sub.2 apertures in the second array through the M.sub.N apertures in the N-th array receiving the electromagnetic wave signal from the substantial number of the M.sub.1 apertures in the first array is configured to redirect the received electromagnetic wave signal back to the substantial number of the M.sub.1 apertures in the first array, and the substantial number of the M.sub.1 apertures in the first array is further configured to send the electromagnetic wave signal to another one of the M.sub.1 apertures in the first array after receiving the redirected electromagnetic wave signal from a M.sub.N-th aperture in the N-th array.

Optical zoom system comprising an image sensor, an objective having multiple refractive surfaces and a focus tunable lens which has a tunable optical power, an expansion unit which is arranged to alter a total track length, wherein in the total track length is measured from a first refractive surface of the objective to the image sensor along the optical path.

A camera module includes a housing; a plurality of movable lens modules disposed in an internal space of the housing and configured to be movable in an optical axis direction, each of the plurality of movable lens modules comprising at least one lens; and a stopper configured to prevent contact between at least two of the plurality of movable lens modules, wherein the stopper includes a frame mounted on the housing; an extension portion extending from the frame into the internal space of the housing to face a side of one movable lens module of the plurality of movable lens modules in the optical axis direction; and a damping member disposed on the extension portion to face the side of the one movable lens module in the optical axis direction.

An image-acquiring equipment with camera with linear sensor is described, having a telecentric optical objective whose main lens 23 is of the cylindrical type, placed in the same way as of the main lens of a known telecentric optics; the lens 23 can be of an a-cylindrical type, with profile computed for removing the cylindrical aberration; the optical assembly 13 for forming a real image 16 on the sensor 26 of the linear camera can be replaced with an optics of the photographic type, obtaining the best possible exploitation of the opening A of the main lens 23, greatly simplifying the construction of the telecentric optics; the image-acquiring equipment comprises a telecentric optics 27, a lamp 34 and a camera 24 of the linear or array type, and is pertaining to a viewing system for dimensional, geometric, or metrological checks.

The imaging optical system consists of a first optical system and a second optical system in order from a magnified side. The first optical system consists of a 1a lens group, first optical path bending means, and a 1b lens group in order from the magnified side, and the second optical system consists of a 2a lens group, second optical path bending means, and a 2b lens group in order from the magnified side. The second optical system forms an image on an image display surface as an intermediate image, and the first optical system forms the intermediate image on a magnified-side conjugate plane, to satisfy the following predetermined Conditional Expression (1).

3<d/I  (1)