UVIT Gratings
The gratings, with 400 lines/mm, are ruled on CaF2 substrate of 4.52 mm thickness. Area of the ruling is 36 mm X 36 mm. The dispersion obtained on the detector plane is 1.2 nm/ arcsec & 0.6 nm/arcsec in the first and second orders respectively at 136 nm. Aberrations are introduced by the grating and the PSF is ~ 2" FWHM. Grating specifications and the measured transmission curves are listed below.
| FUV | NUV | ||
| Substrate | CaF2 | CaF2 | CaF2 |
| Grooves | 400 lines/mm | 400 lines/mm | 400 lines/mm |
| Diameter | 52.00 mm | 51.95 mm | 51.99 mm |
| Thickness | 4.52 mm | 4.52 mm | 4.52 mm |
| Ruled Area | 36 x 36 mm | 36 x 36 mm | 36 x 36 mm |
| 1st Order Peak λ | 190 nm | 240 nm | 210 nm |
| 2nd Order Peak λ | 140 nm | 156 nm | 154 nm |
| Crossover | 150 nm | 175 nm | 166 nm |
Transmission efficiency of FUV Grating-1, measured in Lab
Transmission efficiency of FUV Grating-2, measured in Lab
Transmission efficiency of NUV Grating, measured in Lab