Richardson Ships Mosaic Gratings to Japanese Observatory

Using a mosaic technique, the Richardson Grating Laboratory (Rochester, NY) has produced a trio of diffraction gratings for the Subaru astronomical telescope (Mauna Kea, HI). The components, consisting of two cross disperser and one echelle gratings, are the largest of their kind ever built (see Figure 1). The components are designed to operate in the near infrared, visible, and ultraviolet portions of the spectrum, with better than 70% efficiency.

Figure 1. Mosaic gratings will act as dispersing elements for Subaru telescope. (Courtesy of Richardson Grating Laboratory)

Fabricated on Zerodur substrates for thermal stability, the cross dispersers are 650 mm x 420 mm x 110 mm; the echelle grating is 850 mm x 320 mm x 130 mm. The gratings consist of two smaller patterns replicated onto the same substrated; the surfaces contain 400, 250, and 31.6 grooves/mm. respectively. The two transferred groove surfaces are oriented parallel to within one arc second.