The f/3.2 500-mm focal length monochromator from McPherson Inc. was designed for 120 × 150-mm gratings. Model 205 delivers good light-gathering power, light throughput and spectral resolution. Optical coatings can be specified to further optimize reflectivity or spectral agility. Two exit ports are provided, with the imaging delivered to the lateral port and the resolution to the axial port. Two entrance ports also are available, as are interchangeable gratings for operation at f/4.3 or f/6.9. Model 205's fast aperture ratio makes it suitable for Raman, photoluminescence or low-light applications.