Superconducting thin-film gyroscope readout for Gravity Probe-B

We describe the high-resolution gyroscope (gyro) readout system for the Stanford Gravity Probe-B experiment, whose purpose is to measure two general relativistic precessions of gyroscopes in Earth orbit. In order to achieve the required resolution in angle (0.001 arc · s), the readout system combines high-precision mechanical fabrication and measurement techniques with superconducting thin-film technology, ultra-low magnetic fields, and Superconducting Quantum Interference Device (SQUID) detectors. We discuss system design, performance limits achievable with current technology, and the results of fabrication and laboratory testing to date.