The current and future laser tracking mission requirements of Sandia National Laboratories are discussed. The capabilities of Sandia's existing laser trackers are summarized. The deficiencies of the current laser trackers are identified with respect to future mission requirements. Candidate commercial technologies are addressed to correct the identified deficiencies. Technology gap areas are identified where additional research needs to be conducted prior to developing an effective next generation laser tracking system
Sandia brought its first laser tracking system on-line in 1968 to replace the fixed camera technique for producing trajectory data on test vehicles. Today, test operations are supported by two mobile self-contained tracking systems. These standalone systems provide accurate time-space- position information and high speed photometric coverage.
At Sandia Labs' Coyote Canyon Test Complex, it became necessary to develop a precision single station solution to provide time space position information (tspi) when tracking airborne test vehicles. Sandia's first laser tracker came on line in 1968, replacing the fixed camera technique for producing trajectory data. This system shortened data reduction time from weeks to minutes. Laser Tracker II began operations in 1982, replacing the original tracker. It incorporated improved optics and electronics, with the addition of a microprocessor- based real-time control (rtc) system within the main servo loop. The rtc added trajectory prediction with the loss of adequate tracking signal and automatic control of laser beam divergence according to target range. Laser Tracker III, an even more advanced version of the systems, came on line in 1990. Unlike LTII, which is mounted in a trailer and must be moved by a tractor, LTIII is mounted on its own four-wheel drive carrier. This allows the system to be used at even the most remote locations. It also incorporated improved optics and electronics with the addition of absolute ranging, acquisition on the fly, and automatic transition from manual joystick tracking to laser tracking for aircraft tests.
Laser Tracker II has essentially one moving part. A double-gimbaled mirror directs two laser beams to a cooperative target. The mirror catches the return beams and an optical image for test information. The receivers for the return beams are image dissectors. During the test the dissectors sense a change in target position and generate an error signal to drive the mirror. To produce real-time three-dimensional position data, the tracker uses range, azimuth, and elevation readings. This raw data is shipped through the real-time control microcomputer system to a minicomputer which is also used to operate the tracker. A second minicomputer is used to produce finished trajectory data.