Dichroic optical filter

A dichroic optical filter, including:

• a substrate that is substantially transparent to visible radiation, wherein the substrate has a front surface;
• a coating on the front surface, wherein the coating includes:
• an oxide semiconductor layer that is highly reflective to a selected infrared wavelength and is substantially transparent to visible radiation;
• and
• a first multilayer coating for enhancing the filter's reflectance to the selected infrared wavelength, wherein the first multilayer coating includes thick layers having a higher refractive index alternating with thick layers having a lower refractive index, wherein each of the thick layers has an optical thickness substantially equal to one quarter of the selected infrared wavelength, and wherein each of the thick layers is substantially transparent to visible radiation, wherein the coating also includes a second multilayer coating that partially reflects a narrow wavelength band of visible radiation, and is highly transmissive to visible wavelengths outside the narrow wavelength band.

A dichroic optical filter, including:

• a substrate that is substantially transparent to visible radiation, wherein the substrate has a front surface;
• a coating on the front surface, wherein the coating includes:
• an oxide semiconductor layer that is highly reflective to a selected infrared wavelength and is substantially transparent to visible radiation;
• and
• a first multilayer coating for enhancing the filter's reflectance to the selected infrared wavelength, wherein the first multilayer coating includes thick layers having a higher refractive index alternating with thick layers having a lower refractive index, wherein each of the thick layers has an optical thickness substantially equal to one quarter of the selected infrared wavelength, and wherein each of the thick layers is substantially transparent to visible radiation, wherein the selected infrared wavelength is 10.6 micrometers.

A micromanipulator system, including:

• a source of coherent radiation;
• and
• a beam combining optic positioned to receive the coherent radiation, and comprising a substrate having a front surface and a coating on the front surface, wherein the substrate is substantially transparent to visible radiation, wherein the coating includes an oxide semiconductor layer, and wherein the oxide semiconductor layer is highly reflective to a selected infrared wavelength and substantially transparent to visible radiation, wherein the coating also includes:
• a first multilayer coating for enhancing the reflectance of the beam combining optic to the selected infrared wavelength, wherein the first multilayer coating includes thick layers having a higher refractive index alternating with thick layers having a lower refractive index, wherein each of the thick layers has an optical thickness substantially equal to one quarter of the selected infrared wavelength, and wherein each of the thick layers is substantially transparent to visible radiation, and wherein the first transparent to visible radiation, and wherein the first multilayer coating also includes:
• a plurality of thin layers between each adjacent pair of thick layers, wherein the thin layers in each said plurality of thin layers have optical thicknesses and refractive indices selected so that said plurality of thin layers enhances the filter's transmission of visible radiation without significantly affecting the filter's reflection of the selected infrared wavelength.

A dichroic optical filter, including:

• a substrate that is substantially transparent to visible radiation, wherein the substrate has a front surface;
• a coating on the front surface, wherein the coating includes:
• an oxide semiconductor layer that has a reflectivity of more than 50% to a selected infrared wavelength and is substantially transparent to visible radiation;
• and
• a first multilayer coating for enhancing the filter's reflectance to the selected infrared wavelength, wherein the first multilayer coating includes thick layers having a higher refractive index alternating with thick layers having a lower refractive index, wherein each of the thick layers has an optical thickness substantially equal to one quarter of the selected infrared wavelength, and wherein each of the thick layers is substantially transparent to visible radiation, and wherein the combined reflectivity of the first multilayer coating and the oxide semiconductor layer to the selected infrared wavelength is substantially equal to at least 90%.