This structure includes a transparent member. The transparent member has a first surface and a second surface arranged to face each other, and allows light entering from the first surface to propagate toward the second surface by reflection. The transparent member has a plurality of slopes inclined with respect to the first surface, in an optical path between the first surface and the second surface.

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.

A camera module, a camera assembly, and an electronic device are disclosed, which relate to the field of smart devices. The camera module includes a fixing member, a lens assembly, an image sensor, and a focusing assembly. The image sensor is configured to receive light transmitting through the lens assembly. In the focusing assembly, a first light-redirecting member is configured to redirect the light transmitting from the lens assembly to the image sensor; a second light-redirecting member is configured to redirect the light redirected by the first light-redirecting member, and configured to be movable relative to the fixing member to change a transmission distance of the light from the lens assembly to the image sensor.

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.

A lens device includes a first lens module, a first light path turning module and an image sensor. The first lens module, the first light path turning module and the image sensor are sequentially arranged along a light path in which a light beam propagates. The first light path turning module is configured to change a direction in which the light beam propagates so that the light beam passes through the first lens module to form an image on the image sensor.

A focusing device comprises a base unit and a mirror unit which is translatable relative to the base unit parallel to an optical axis of the focusing device. The mirror unit is configured to receive incident light along the optical axis in a first direction and to reflect the incident light parallel with the optical axis in said first direction. The mirror unit comprises at least four mirrors, at least one of the mirrors being curved.

A lens device includes a first lens module, an image sensor and a first light path turning module. The first lens module includes plurality of lenses. The first light path turning module is configured to transmit a light beam passing through the first lens module to the image sensor by exactly three or four reflections. The first light path turning module includes three or four reflecting surfaces on which the reflections occur. All the reflecting surfaces are plane surfaces. The first light path turning module includes no free form surface. All the surfaces on which the light beam is reflected are plane surfaces, wherein the plane surfaces are flat and are different from freeform surfaces.

A wavelength division multiplexing structure includes: a first reflecting surface; a second reflecting surface; a first optical filter; a second optical filter; and a pretreatment device. The light that is incident on the first reflecting surface forms a first C-shaped light path in C-shaped or approximately C-shaped and enters the first optical filter. The light that is incident on the first reflecting surface forms a non-coplanar straight line with the light that is reflected by the second reflecting surface. The light that is incident on the pretreatment device forms a pretreatment light path, enters the first optical filter. The light in the pretreatment light path coincides with the light in the first C-shaped light path that is incident on the first optical filter from the second reflecting surface.

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.

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.