An optical assembly is part of an optical system such as a laser communication system on a moveable platform that operates in a range of temperature extremes. The optical assembly has a mount with a plurality of supports that couple an optical mirror to a frame or chassis of the optical system. The supports may be selectively heated or cooled in accordance with their respective coefficients of thermal expansion to reduce, minimize, or eliminate angular drift of the mounted optic or mount. The supports expand or contract to correct for misalignments of the beam reflection angle to improve the accuracy and efficiency of the optical system without significantly increasing size, weight, and power of the optical system.

A diffractive optical element prevents degradation of the optical performance of the element due to moisture absorption of the resin layers from taking place and also can prevent cracks of the resin layers and peeling of the resin layers along the interface thereof from taking place in a hot environment or in a cold environment. The diffractive optical element comprises a first layer and a second layer sequentially laid on a substrate, a diffraction grating being formed at the interface of the first layer and the second layer, the height d of the diffraction grating, the average film thickness t1 of the first layer and the average film thickness t2 of the second layer satisfying the relationship requirements expressed by the expressions of 1.1dt150 m and 30 mt2(400 mt1d).

The disclosure provides a method that includes filling a cavity in a substrate with a second material, wherein the substrate includes a first material. The method also includes using galvanic and/or chemical deposition of a third material to apply an overcoating to a first surface of the substrate in a region of the cavity. The method further includes removing the second material from the cavity. In addition, the method includes, before or after removing the second material from the cavity, applying a reflective layer to the overcoating. The disclosure also provides related optical articles and systems.

There is herein described a ceramic wavelength converter having a high reflectivity reflector. The ceramic wavelength converter is capable of converting a primary light into a secondary light and the reflector comprises a reflective metal layer and a dielectric buffer layer between the ceramic wavelength converter and the reflective metal layer. The buffer layer is non-absorbing with respect to the secondary light and has an index of refraction that is less than an index of refraction of the ceramic wavelength converter. Preferably the reflectivity of the reflector is at least 80%, more preferably at least 85% and even more preferably at least 95% with respect to the secondary light emitted by the converter.

An EUV collector mirror for an extreme ultra violet (EUV) radiation source apparatus includes an EUV collector mirror body on which a reflective layer as a reflective surface is disposed, a heater attached to or embedded in the EUV collector mirror body and a drain structure to drain melted metal from the reflective surface of the EUV collector mirror body to a back side of the EUV collector mirror body.

An optical assembly includes: an optical element, which is transmissive or reflective to radiation at a used wavelength and has an optically used region; and a thermally conductive component, which is arranged outside the optically used region of the optical element. The thermally conductive component can include a material having a thermal conductivity of more than 500 W m.sup.1 K.sup.1. Additionally or alternatively, the product of the thickness of the thermally conductive component in millimeters and the thermal conductivity of the material of the thermally conductive component is at least 1 W mm m.sup.1 K.sup.1.

The present disclosure provides a hair removing device, including: a reflector, a light source, a first light-transmitting body, a heat dissipation base and a refrigerating member. The light source is arranged inside the reflector and can emit light. The reflector can reflect light, such that the hair removing device can emit light to remove the hair from the skin. The first light-transmitting body and the reflector cooperatively define a cavity to receive the light source. A body of the light source is suspended in the cavity. Two sides of the heat dissipation base are thermally coupled to the reflector and the refrigerating member respectively.

The invention relates to a microelectromechanical apparatus (100, 200) comprising one or more microelectromechanical devices (130) each having a mirror element (134), an actuator (132) for moving the respective mirror element (134), and a heating element (138, 240) for heating the respective mirror element (134), wherein the microelectromechanical apparatus (100) comprises one or more temperature sensors (135, 145, 210, 212) and an electronic system (125, 225), wherein the control electronic system (125, 225) is configured to determine a temperature value of the respective mirror element (134) using the one or more temperature sensors (135) for each mirror element (134), and the electronic system (125, 225) is further configured to adjust a heating power for each of the heating elements (138, 240). The invention further relates to an illumination optical unit (172), to an illumination system (174) and to a projection exposure apparatus (170), each having a microelectromechanical apparatus (100, 200) according to the invention, and to a method for controlling temperatures of a microelectromechanical apparatus (100, 200) in a closed-loop.

An optical module for a machine for machining workpieces and/or for producing molded bodies by location-selective solidification of material powder to form connected regions by a focused laser beam includes a housing for releasably attaching the optical module to the machine and a plurality of optical components are arranged in or on the housing to collimate and focus the laser beam.

A heating arrangement, for example for use in a microlithographic projection exposure apparatus, comprises: at least one beam shaping unit for beam shaping of the electromagnetic radiation steered from a radiation source to the at least one optical element; and a sensor arrangement having at least one intensity sensor. The at least one beam shaping unit comprises at least one microstructured element for steering some the electromagnetic radiation to the sensor arrangement when the heating arrangement is in operation. Methods are provided.