  High-contrast imaging has been used to discover and characterize dozens of
exoplanets to date. The primary limiting performance factor for these
instruments is contrast, the ratio of exoplanet to host star brightness that an
instrument can successfully resolve. Contrast is largely determined by
wavefront error, consisting of uncorrected atmospheric turbulence and optical
aberrations downstream of AO correction. Single-point diamond turning allows
for high-precision optics to be manufactured for use in astronomical
instrumentation, presenting a cheaper and more versatile alternative to
conventional glass polishing. This work presents measurements of wavefront
error for diamond-turned aluminum optics in the Slicer Combined with an Array
of Lenslets for Exoplanet Spectroscopy (SCALES) instrument, a 2-5 micron
coronagraphic integral field spectrograph under construction for Keck
Observatory. Wavefront error measurements for these optics are used to simulate
SCALES' point spread function using physical optics propagation software poppy,
showing that SCALES' contrast performance is not limited by wavefront error
from internal instrument optics.
