SCARI Instruments

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"SCARI --Self-Compensating All-Reflecting Interferometer-- splits light from a single source and sends those two beams along different paths. The two beams recombine at a focal plane and small differences in their path lengths will cause them to mis-align, thus interference. The light waves in the two beams interfere with each other, much like two water waves can interfere. When the peaks of the two waves line up, or are in phase, constructive interference occur and bright lines or patches are seen. When the peaks do not line up, or are out of phase, destructive interference occurs and dark patches are seen. The bright and dark lines together create fringes." (Chakrabarti, et al,Applied Optics,33,2596)

Interferometric fringes generated by a HeNe Laser:

Hydrogen Lyman alpha fringes at 1215.67 Angstroms:

SCARI instruments: Interferometer(black/right) and Collimator(silver/left):

SCARI (above) works in the ultraviolet (UV), and consists of four optical elements that are specially coated. The optics are housed in a coffin-shaped box which is then attached to a bulkhead. A simple telescope, or collimator, sits opposite SCARI
and is shown on the left side of the bulkhead. The collimator directs light into the system.

SCARI Instrument Assembly

The mechanical parts of SCARI are aluminum. The interferometer is black due to a coating used to harden it. SCARI is held together with hundreds of small bolts, all of which need to be tightened down in a precise manner. Below, a mirror is being attached to SCARI.

The other instruments and parts must also be assembled, and everything attached to the bulkheads. Below, the star tracker mount is being attached to the bulkhead. The collimator can also be seen, already attached, below the star tracker mount.

Finally, all the bolts are staked, or glued down to prevent them from backing out. Then, the electronics and cables are all attached.