The Large Optical Test and Integration Site (LOTIS) at the Lockheed Martin Space Systems
Company in Sunnyvale, CA, has successfully reached Initial Operational Capability (IOC).
LOTIS is designed for the verification and testing of optical systems. The facility consists of a
large, temperature stabilized vacuum chamber that also functions as a class 10k cleanroom.
Within this chamber and atop an advanced vibration-isolation bench are the 6.5 meter diameter
LOTIS Collimator and Scene Generator, LOTIS alignment and support equipment. IOC included
completion of the entire facility as well as operation of the LOTIS collimator in air. Wavefront
properties of the collimator will be described as well as facility vibration isolation properties and
turbulence levels within the collimator test chamber. User-specific test capabilities will also be
addressed for two major areas of concern.
Lockheed Martin Space Systems Company has completed the Large Optical Test and Integration Site (LOTIS) at its
Sunnyvale, CA campus. Central to the LOTIS testing facility is a 6.5-meter diameter optical collimator housed in a
large, temperature controlled and vibration isolated high-vacuum chamber. A measurement has been made of the
atmospheric turbulence inside the LOTIS vacuum chamber testing environment at ambient pressure and temperature
near floor level where distorting turbulence may be most persistent. Turbulence is one of the many components that
define the overall LOTIS Collimator optical testing capabilities at ambient air pressure. Experimental measurements
have been made with a non-phase-shifting Fizeau interferometer along a 50-foot horizontal propagation path in double
pass. Results presented here represent root-mean-square (RMS) wavefront error over an 18-inch aperture and the
corresponding atmospheric coherence length, <i>r</i><sub>o</sub> (Fried's parameter). In addition, an analysis was performed to calculate
the optical line-of-sight jitter response of the LOTIS Collimator system and facility due to base-level vibration
disturbances. Vibration survey measurements were made using accelerometers mounted to the vacuum chamber
foundation to create a Power Spectral Density (PSD) plot of the measured seismic and vacuum chamber mechanically
induced vibration disturbances. The measured PSD was used as the base input to a system-level finite element model
that included the LOTIS Collimator, the Flat Mirror Positioning structure and a generic Unit Under Test all mounted on
the LOTIS Vibration Isolation Bench to assess the whole system jitter response. Results presented here represent the
RMS jitter in nanoradians through the optical path of the LOTIS Collimator due to base-level induced seismic and
chamber mechanical vibrations.