Finding the components of an optical system that are most sensitive to misalignment allows a designer to insulate them from outside perturbations or incorporate compensators to account for alignment errors. At Advanced Optical Systems, Inc. (AOS) we used opto-mechanical constraint (OMC) equations to analyze the misalignment sensitivity of an optical correlator system and develop a better design. The OMC equations provide sensitivity coefficients for each element in the design that can be used to determine which components create the greatest image shift and focus errors when not optimally aligned. The OMC analysis model of the optical correlator was verified using a test bench with lenses in adjustable mounts to induce known amounts of misalignment in multiple axes. The experimental data matched the calculated values for each tested lens. The OMC coefficients assisted in identifying (1) lenses that are sensitive to loose manufacturing tolerances, (2) where subsystem designs can be beneficial, and (3) materials that provide optimum thermal performance. We will show results from our latest optical correlator package built using the OMC model analysis, which was critical to making decisions in the opto-mechanical design state of system development. We will also discuss a MATLAB simulation of AOS' optical correlator that incorporates the opto-mechanical constraints into a digital simulation of the correlation image.
Advanced Optical Systems, Inc. is developing the Autonomous Rendezvous and Docking Sensor Suite for Marshall Space Flight Center to provide real-time range and 6 Degree Of Freedom (DOF) information. This information facilitates the autonomous docking of two spacecraft. The sensor suite is comprised of the Advanced Video Guidance Sensor (AVGS) and the Wide Angle Laser Range Finder (WALRF). AVGS was developed under NASA's Demonstration of Autonomous Rendezvous Technology (DART) program for a cooperative target and is scheduled to fly in 2004. The prototype of the WALRF is being developed at AOS under a different program. The sensor suite can provide range and bearing data up to 5km and 6 DOF information up to 300m for the DART target configuration. Different target geometries can increase range detection and 6 DOF detection distance. The sensor suite is a laser-based optical system with a combined weight of less than 40lbs and a combined volume of less than 12”×10”×18”. The WALRF system employs a bistatic transceiver with an 8° field of view (FOV). This sensor is a time-of-flight range finder with a quad detector. The AVGS section of the suite is a monostatic transceiver with a 16° FOV and high-speed imager. This section of the suite uses a pattern recognition system that reduces imager data into 6 DOF information. In this paper we will outline in detail the AVGS and WLRF functionality as well as experimental range data and measurement accuracy.