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The 4" by 4" square, 40" long EXES grating. The grating was diamond-machined from a single piece of Al 6061 by Hyperfine, Inc. The hole bored down the center is to lightweight the grating.
A side view of the EXES grating. Note the stairstep pattern of the grooves. The dark stripes are the illuminated faces we care about.
Another view of the EXES grating.
Looking at the grating from near blaze. Note the image of the photographer at the far end of the grating
Lab results from the TEXES (ground-based prototype) spectrograph with an emission gas cell.
A blow up of the TEXES gas cell results. Note that the methane lines near 7 microns are not well fit by a Gaussian. The acetylene lines near 13 microns are very well fit by a Gaussian.
A TEXES image (actually a nod pair with the top image positive and the bottom image negative) of Beta Peg at the IRTF. The top countour is approximately the FWHM with successive contours down by root(10). There are hints of the Airy pattern, indicating we were close to the diffraction limit of the telescope.
A pupil image of the IRTF taken with TEXES. This image shows the secondary mirror and the spider. TEXES's pupil is about 10% too big; we can see the spider directly at the edge of our pupil.