Successful testing of the LISA Technology Package (LTP) interferometer engineering model

The LISA Technology Package (LTP), to be launched by ESA in 2008, is a technology demonstration mission in preparation for the LISA spaceborne gravitational wave detector. A central part of the LTP is the optical metrology package (heterodyne interferometer with phasemeter) that measures the distance between two test masses with a noise level of 10 pm Hz -1/2 between 3 mHz and 30 mHz and also the test mass alignment with a noise level of <10 nrad Hz -1/2 . An engineering model of the interferometer has been built and environmentally tested. Extensive functionality and performance tests were conducted. This paper reports on the successful test results.