SBL Team test beam director design
26 January 2001http://defence-data.com/storypic/sblifx.jpg [not image]
The Space-Based Laser Integrated Flight Experiment (SBL-IFX) has new information about how to monitor and maintain the pointing of the SBL-IFX beam director on orbit. The data was collected from a recent integrated ground test of the Alpha high-energy laser, its beam director telescope and the associated beam alignment and correction system.
The beam director is the part of the Air Force and Ballistic Missile Defense Organisation's (BMDO) proposed experimental missile defence system that will project the high-energy laser beam across space and focus it on a distant boosting missile target.
Team SBL-IFX, a joint venture comprising Lockheed Martin, TRW and Boeing, conducted the six-second lasing test last month at TRW's Capistrano Test Site near San Clemente in California. It was carried out as part of the team's current $240 million SBL-IFX development contract with the Air Force.
The test involved generating a megawatt-class laser beam with the TRW-built Alpha, then feeding it through the Lockheed Martin-built beam control system and a 4-meter diameter beam director telescope, both of which are housed in a special vacuum chamber that simulates the space environment.
The primary goal of the test was to see if the telescope's metrology systems could maintain the pointing and proper alignment of its primary and secondary optics.
"The test was a solid success," declared Col. Neil McCasland, director of the Air Force's SBL-IFX project office. "The laser operated nominally, the software designed to maintain the positions of the beam director optics during lasing performed as designed, and we collected a wealth of diagnostic data about the high-energy laser environment."
The telescope and beam alignment and correction system used during the test are both operated by Lockheed Martin. They were integrated with the Alpha laser in the early 1990s as part of the Alpha LAMP (Large Advanced Mirror Program) Integration program, one of several previous SBL technology demonstration programmes.
A secondary goal of the test, added McCasland, was to find out if laser characteristics such as power, beam uniformity and frequency spectrum would be adversely affected by the interaction of the laser beam with the optical systems used to correct, point and focus the beam on its target. Initial evaluation of the test data indicates that no such adverse interactions occurred.
"A critical part of a successful on-orbit IFX demonstration is being able to know precisely where the beam director will direct the laser beam," explained Art Woods, Lockheed Martin's SBL programme manager. "We proved with this test that the metrology systems designed to measure the alignment of the beam director telescope and the relationship between the beam director's primary and secondary mirrors can operate effectively in the presence of the high-power laser beam."
The integrated Alpha/LAMP test is the latest in a series of technical risk reduction activities that Team SBL-IFX has undertaken since May 1999 to develop and mature the component technologies required to produce, integrate and perform a ground-based demonstration of a full-scale SBL-IFX integrated test unit before the end of the decade.
The SBL-IFX, a satellite carrying a high-energy laser, is scheduled to be launched in 2012, with an on-orbit demonstration of its defensive capabilities against a live, boosting target planned for 2013.
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