Abstract: A cooled mirror structure useful in a high power laser optical system, constructed with a substrate formed of a material having a thermal conductivity peak in a cryogenic temperature operating range. During operation, the temperature of the substrate is maintained within the cryogenic temperature operating range to maintain the thermal conductivity within the peak, while the low cryogenic temperature also results in an extremely low coefficient of thermal expansion for the substrate. The combination of high thermal conductivity and a low coefficient of thermal expansion provides a mirror structure capable of handling extremely high energy flux loadings with a minimum amount of resultant surface deformation.

Abstract: An arrangement for laser beam welding wherein at least one of the components being welded is formed of a material which is substantially transparent to radiation at the wavelength of the laser welding beam. A layer of welding material is placed over the surface area of the weld joint, and is a type of material which is substantially absorbent of radiation at the wavelength of the laser welding beam. The welding material is then irradiated by the laser beam through the component which is substantially transparent thereto for a sufficient period of time to cause melting of the welding material and fusion thereof to the two components being welded. The present invention has particular applicability to welding with a Nd-YAG laser of components formed of silica-containing material, such as fused silica or titanium silicate, and wherein the welding material placed at the weld surface area is a titanium based material.

Abstract: A mirror structure designed to minimize damage to the mirror caused by soft X-rays. A reflective coating having a high reflectivity at wavelengths of interest is deposited on a glass substrate. The reflective coating has a moderately low atomic number to reduce direct susceptibility to substantial X-ray damage, and further has a high coefficient of thermal conductivity so that it is a good conductor of heat from the reflective coating to the glass substrate. Unfortunately, glass is a poor conductor of heat, and the accumulation of absorbed energy in the reflective coating will rapidly lead to crazing, melting, and vaporization. Accordingly the mirror structure is designed with a heat sink coating between the reflective coating and the glass substrate. The heat sink coating has a higher coefficient of thermal conductivity than glass so that it conducts heat away from the reflective coating, and also has an atomic number which is lower than glass so that it is subject to less X-ray energy absorption.