An optical element includes a hologram layer, a resin substrate to which the hologram layer is adhered, and a holder portion that supports the resin substrate and has a thermal expansion coefficient smaller than that of the resin substrate. One of the holder portion and the resin substrate includes a contact surface along an axis extending in a plate thickness direction of the resin substrate, and the other of the holder portion and the resin substrate includes a pressing surface that presses the contact surface.

A lighting apparatus for vehicles with a number of semiconductor-based light sources and a projection device for generating the specified light distribution with a cut-off line. The projection device features a correction device with at least two lenses. The surface of at least one of the lenses is designed as a diffractive lens surface for achromatization in a visible wavelength range. The two lenses are made from different lens materials. The surfaces of at least two lenses are designed as refractive lens surfaces that have their optical power calculated based on a temperature range and/or expansion coefficient of the lens material of at least two lenses such that adding the optical power of the lenses yields a predefined total optical power of the correction device.

Methods and systems for heating a space deployed membrane assembly are provided. The membrane assembly can include one or more framed sections. Each section can include a composite membrane having a membrane substrate and a transparent, electrically conductive resistive coating. The composite membrane is held within a frame. Electrically conductive bus bars are provided and are placed in intimate electrical contact with the resistive coating. The electrically conductive bus bars are generally arranged, on opposite sides of the perimeter of the membrane. A controller passes current between selected bus bars, with different bus bars operative to pass current between them at different times. The magnitude of the voltage applied to the bus bars, the location of the bus bars, the operational sequence of powering the bus bars, and the time over which current is passed between a selected pair of bus bars, are selected to provide substantially uniform time averaged heating of the membrane.

Optical scanner and electrophotographic image forming apparatus are provided. The optical scanner includes a light source, configured to emit a light beam; an optical deflector, configured to deflect the light beam emitted from the light source; a first optical unit, arranged there-between and including a refraction unit and a diffraction unit; and a second optical unit, arranged in a light exit direction of the optical deflector and configured to make the light beam deflected by the optical deflector form an image on a scanning target surface. A range of a ratio of a refractive power Φ.sub.r to a diffractive power Φ.sub.d of the first optical unit in a main scanning direction is 0.3<Φ.sub.r/Φ.sub.d<0.5; and a range of a ratio of a refractive power Φ.sub.s to a diffractive power Φ.sub.n of the first optical unit in a sub scanning direction is 0.7<Φ.sub.s/Φ.sub.n<1.0.

An optical sheet includes a substrate, a protective structure on a surface of the substrate, and an optical diffraction structure on a side of the substrate opposite to the surface. The substrate is made of a transparent material and defines a projection area and a non-projection area surrounding the projection area. The protective structure includes a metal circuit in the non-projection area and surrounding the projection area. The optical diffraction structure is configured to diffract light.

An optical element of the present disclosure includes a hologram layer, a resin substrate to which the hologram layer is adhered, and a holder portion that supports the resin substrate and has a thermal expansion coefficient smaller than that of the resin substrate. One of the holder portion and the resin substrate includes a contact surface along an axis extending in a plate thickness direction of the resin substrate, and the other of the holder portion and the resin substrate includes a pressing surface that presses the contact surface.

A lighting apparatus for vehicles with a number of semiconductor-based light sources and a projection device for generating the specified light distribution with a cut-off line. The projection device features a correction device with at least two lenses. The surface of at least one of the lenses is designed as a diffractive lens surface for achromatization in a visible wavelength range. The two lenses are made from different lens materials. The surfaces of at least two lenses are designed as refractive lens surfaces that have their optical power calculated based on a temperature range and/or expansion coefficient of the lens material of at least two lenses such that adding the optical power of the lenses yields a predefined total optical power of the correction device.

An optical grating comprising a refractive index with a periodic pattern that includes a base period ?.sub.0; a periodic sampling of the base period, with a first period ?.sub.1 and a first duty cycle p.sub.1, thereby defining a single-sampled grating (SSG); and a periodic sampling of the SSG, with a second period ?.sub.2 and a second duty cycle p.sub.2. The resulting dual-sampled grating (DSG) can have a reflection spectrum containing reflection peaks. If two DSGs having different reflection spectra share a common interface, a tunable optical filter can be produced, where electrical or heating means can cause a reflection peak of one spectrum to be shifted to coincide with a reflection peak of the other spectrum, thereby filtering the corresponding wavelength. By inserting between the two DSGs a gain medium and a phase-tuning medium, a laser source structure is realized. Either device can be produced by etching or stacking methods.

Systems and methods are provided herein. An exemplary system may include a laser source, the laser source having a laser center wavelength; at least one narrowband optical element receiving light emitted by the laser, the narrowband optical element having a filter center wavelength, the narrowband optical element being arranged such that the filter center wavelength is initially spectrally aligned with the laser center wavelength, the filter center wavelength changing in response to a temperature change such that the filter center wavelength is not substantially aligned with the laser center wavelength; and a passive adjustment mechanism coupled to the narrowband optical element, the passive adjustment mechanism including an actuator, the actuator moving in response to the temperature change, the actuator motion rotating the narrowband optical element, the rotation compensating for the temperature change such that the filter center wavelength and laser center wavelength remain spectrally aligned.

Systems and methods are provided herein. An exemplary system may include a laser source, the laser source having a laser center wavelength; at least one narrowband optical element receiving light emitted by the laser, the narrowband optical element having a filter center wavelength, the narrowband optical element being arranged such that the filter center wavelength is initially spectrally aligned with the laser center wavelength, the filter center wavelength changing in response to a temperature change such that the filter center wavelength is not substantially aligned with the laser center wavelength; and a passive adjustment mechanism coupled to the narrowband optical element, the passive adjustment mechanism including an actuator, the actuator moving in response to the temperature change, the actuator motion rotating the narrowband optical element, the rotation compensating for the temperature change such that the filter center wavelength and laser center wavelength remain spectrally aligned.