Vacuum spectrometers from McPherson (Chelmsford, MA) have a 670mm focal length. The spectrometers feature stainless steel housings and components for ultra-high-vacuum applications. The instruments readily achieve 10E-6 torr vacuum during operation with elastomer (Viton™ or Buna-N) seals. The McPherson models have master polished optics, multiple entrance and exit port locations, and high precision wavelength drives for wavelength reproducibility. Specialized high reflectivity coatings provide up to 78% reflective efficiency at wavelengths as short as 120 nm. The device has an f/4.7 aperture ratio (670mm f.l.). The tools are available in focal lengths of 0.67, 1.0, 1.3, and 2-meters.