Engineering topics

Hilliard, R. L.

Publications and source records attributed to Hilliard, R. L..

3 records

NASA NTRS1991

A Cassegrain echelle spectrograph

The 'LPL echelle' is a CCD spectrograph with a resolving power of 160,000 and enough sensitivity to detect the brighter airglow emissions in a few minutes. It uses an R3.2 grating in a novel out-of-plane mounting that permits any wavelength to be placed on the blaze. A single order is selected by a medium-band interference filter. Lower dispersions and broader wavelength coverage are obtained by replacing the echelle by a 600 line/mm grating or a Littrow prism.

Hunten, D. M.↗

NASA NTRS1982

Actual blaze angle of the Bausch & Lomb R4 echelle grating

An innovative procedure is described for measuring blaze angle that is free of systematic effects associated with an alternative approach. The method uses the effect of facet diffraction on the blaze function when an echelle grating is used off-Littrow. The angle measurement in the Littrow condition is wavelength independent and locates the actual direction of the grating facet normal.

Brown, R. A.↗

NASA NTRS1980

Echelle efficiencies - Theory and experiment

The effect of one echelle spectrograph design factor, orientation of the incident light bundle, is examined. Comparison of theoretical calculations and experimental measurements of echelle grating efficiencies are given for R2 echelles used in three possible configurations: alpha greater than beta, alpha smaller than beta, and the quasi-Littrow mode. The throughput-resolution products for these various cases are also compared.

Schroeder, D. J.↗