Front Surface Aluminum Mirrors (150 – 900 nm)

Broadband Mirrors for the UV, VIS and NIR

Optical Properties

• Unprotected aluminum:
  • R > 80 % at 193 nm
  • R = 92 % at 248 nm
  • R > 85 % from 200 nm to 950 nm
  • R > 90 % from 230 nm to 600 nm
  • R > 90 % for λ > 1 µm

• Standard mirror:
  • R = 82 … 92 % from 240 nm to 550 nm
  • R = 85 … 92 % from 550 nm to 950 nm
  • R > 92 % for λ > 1 µm

Aluminum is the metal with the highest reflectance in the UV spectral range. Besides this, aluminum has a high and relatively constant reflectance in the VIS and NIR. The minimum in the reflectance curve around 800 nm is due to a phonon resonance and can only be overcome by a dielectric protective coating. The reflectance in the VIS and UV spectral range can be influenced by the coating technologies. In case of protected aluminum mirrors, the positions of the minima and maxima of the reflectance depend on the design of the protective layer system and on the angle of incidence (AOI). Please specify AOI and the wavelengths of interest so that reflectance may be optimized as much as possible.

Maximum diameter: 600 mm, especially for astronomical applications.

Aluminum Mirrors for Multiple Wavelength and Ultrafast Applications

Fig. 2 shows the reflectance spectra of a mirror optimized for high reflectance at 266 nm, 400 nm and 800 nm at AOI = 45°.

Special Features

• High reflectance in the wavelength range specified
• Extremely low scattering losses of protected aluminum mirrors (total scattering TS < 100 ppm at 633 nm, TS < 1000 ppm at 248 nm, TS < 5000 ppm at 193 nm)
• Standard mirrors can be cleaned using ethanol or acetone and are resistant to moderate abrasion (tested according to MIL-M-48497A § 4.5.4.2 and § 4.5.3.3)
• All mirrors are resistant to humidity (tested according to MIL-M-13508C §4.4.7)
• Highly stable optical parameters because of sputtered SiO₂ protective layer

Protected Aluminum Mirrors for the DUV and VUV

Optical Properties

• Special coating design depending on the wavelengths of interest:
  • Optimized for 157 nm: R = 74 … 78 % for 157 nm
    (R > 70 % from 150 to 200 nm)
  • Optimized for 193 nm: R = 75 … 80 % for 193 nm
  • Optimized for 248 nm: R > 90 % for 248 nm

Enhanced Aluminum Mirrors for 157 nm

• Reflectance at 157 nm can be further improved by dielectric protective coatings (up to R > 94 %)
• Reflectance in the VIS: R = 60 … 80 %. This can be used for an alignment laser
• Especially mirrors with R = 85 … 90 % can be used at a wider range of AOI than all dielectric mirrors of this reflectance

Enhanced Aluminum Mirrors for 193 nm

• Reflectance at 193 nm can be improved up to Ru > 95 %
• This kind of mirrors can also be used as scanning mirror for AOI = 45° – 50° with Ru > 93 %
• Reflectance in the VIS: R = 60 … 80 %. This can be used for an alignment laser
• VUV optimized mirrors should be treated with extreme care