Assembly, Integration, and Verification of the GMT-Consortium Large Earth Finder Red Channel Camera Optics

The GMT-Consortium Large Earth Finder (G-CLEF) is a designed fiber-fed, optical echelle spectrograph (350 to 950 nm) that is to be a first light instrument for the Giant Magellan Telescope (GMT). G-CLEF will have four resolution modes (23k ≤ R ≤ 110k) with a precision radial velocity (PRV) goal of 10 cm/sec in the highest resolution mode. A dichroic in the G-CLEF spectrograph optical train separates light into a blue (350 to 540 nm) and a red (540 to 950 nm) channel, each with its own camera optics. This paper will provide an overview of the assembly, integration, and verification (AIV) activities that have begun on the red channel camera optics. The 7-element optical system has been assembled and is undergoing testing. Each element has been aligned within its individual bezel to within ±6 µm in centration, and ±40 µrad in tilt. The AIV setup measures three performance metrics: 1) wavefront error in double-pass, 2) camera stand-alone wavelength trajectory, and 3) VPH grating + camera wavelength trajectory. Interferometric double-pass measured the on-axis wavefront error at 632 nm to be 50.37 nm RMS (λ/12.6). The Stand-alone Camera Wavelength Trajectory tests resulted in < 30% (1.46 nm RMS) of the allotted error budget (5.04 nm RMS) for 80% encircled energy. Volume Phase Holographic (VPH) cross-disperser plus Camera Wavelength Trajectory tests are currently underway.