Abstract: An interferometer measuring system comprising two moveable members and a reference member that may have significantly less movement, the group having a number of attached measurement mirrors, interferometers for measuring position and two optical support blocks for the interferometers. The interferometers are used to determine the measured optical path lengths to each of the moveable members and reference member and these positions are used to calculate the misalignment, or error in the relative positions of the moveable members with respect to the reference member. This calculated error is then used to correct the misalignment by moving the appropriate members in the manner directed by the calculation.

Abstract: A method for packaging an acoustic wave filter (102). The method includes a step of providing a first wafer (100). The first wafer (100) supports acoustic wave transduction and propagation. The method also includes steps of processing the wafer (100) to provide transducer patterns (18, 18') thereon and disposing a seal ring (25) on the wafer (100). The seal ring (25) completely encloses active areas allowing portions of each bond pad to extend outside of the seal ring. The method further includes steps of disposing a second wafer (40) atop the seal ring (25) and the first wafer (100), sealing the second wafer (40) to the first wafer (100), dicing the second wafer (40) with a saw that provides a first kerf width, whereby portions of the second wafer (40) overlying bonding pads (20) of the transducer patterns (18, 18') are removed and dicing the first wafer (100) with a saw that provides a second kerf width narrower than the first kerf width to provide a packaged SAW die.

Abstract: A full duplex radio (10) having improved properties is obtained by using asymmetric surface acoustic wave (SAW) filters (70, 92, 100, 100', 112). The filters (70, 92, 100, 100', 112) are composed of series (50.sub.1, 50.sub.1 ') and parallel (50.sub.2, 50.sub.2 ') coupled SAW resonators. Asymmetry is obtained by covering either of the series (50.sub.1, 50.sub.1 ') or parallel (50.sub.2, 50.sub.2 ') resonators of each filter (70, 92, 100, 100', 112) with a dielectric layer (96) to increase the SAW coupling coefficient (Cs, Cp) of the covered resonators (50.sub.1 ', 50.sub.2 ') relative to the uncovered resonators (50.sub.1, 50.sub.2). The filters (70, 92, 100, 100', 112) are desirably in pairs arranged with mirror image frequency asymmetry such that the steeper skirts (87, 79) of the frequency response (91', 91") are adjacent. Greater pass-band bandwidths (77, 77', 77") can be obtained without adverse affect on transmitter and receiver isolation.