Multiple‐pass monochromators

Multiple-pass double-dispersion accessory optics are now available for the 0.67 to 2 m focal length monochromators from McPherson. McPherson multiple-pass monochromators allow you to work with low f /number, great throughput and twice the resolution. Unique ‘doubling’ of resolution and dispersion is achieved by plane folding mirrors that multiply the monochromator focal length. Inside the instrument the fold mirrors repeat the light path. The monochromator aperture ratio ( f /number) is unchanged. Light passes over the diffraction grating two times. The multiple-pass monochromator is useful for reaching twice the resolution or dispersion with very aggressive f /number and excellent light throughput. Scanning monochromator applications as well as imaging and other CCD-based detection approaches benefit. McPherson multiple-pass monochromators are ideal for experiments where more spectral resolution is required and laboratory space or budget cannot accommodate a physically larger instrument. The multiplepass approach is not to be confused with double monochromators where light passes through two separate instruments to achieve low scatter light levels.