We performed a direct side-by-side comparison of a Shack-Hartmann wave-front sensor and a phase-shifting interferometer for the purpose of characterizing large optics. An expansion telescope of our own design allowed us to measure the surface figure of a 400-mm-square mirror with both instruments simultaneously. The Shack-Hartmann sensor produced data that closely matched the interferometer data over spatial scales appropriate for the lenslet spacing, and much of the <20-nm rms systematic difference between the two measurements was due to diffraction artifacts that were present in the interferometer data but not in the Shack-Hartmann sensor data. The results suggest that Shack-Hartmann sensors could replace phase-shifting interferometers for many applications, with particular advantages for large-optic metrology.

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We employ an alternative technique for determining the Lorentzian linewidth based upon the simultaneous measurement of the vapor transmission and group-velocity delay outside the Doppler core of an optically dense transition. We apply this technique to measure the cross sections for broadening of the intercombination lines of calcium, 4s 'S0~4s4p Pi, and strontium, Ss 'S0~5s5p Pi, by collisions with argon, neon and the ground-state neutral vapor. We compare our measured results with calculated values as well as previously determined values by other workers.PACS number(s): 32.70. Jz, 34.40.+n, 35.80.+s

We describe a technique for determining Nfl by measuring the group-velocity delay of a probe laser beam propagating through a vapor. This diagnostic has wide dynamic range, is simple to implement, and can be used as a high-bandwidth vapor rate monitor. In addition, it can be used to measure column density, Nl, number density, N, oscillator strengths, f, or absorption cross sections, collisional line broadening, and vapor group-velocity delay.

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