PS02@NS.CC.LEHIGH.EDU (Penelope E. Smith) (06/22/91)
Re Laser Measuring: 1) For the accuracy you want, (10 -5 In) You are into laser interferometry. Similar accuracy can also be achieved with glass scale technology (Heidenhain) but this requires contact. There are two interferometry systems in existence which could meet your needs: 1) HP has a laser measuring system using heterodyne interferometry which is commercial. I am under the impression that the cost of the system is about 50K. This gives relative displacement measurements and can also be used to determine such things as straightness. 2) Fastman, Inc. (215) 691-2577, for which I consult, has developed an ABSOLUTE interferometry system, which can give absolute measurements at reasonable bandwidth. We are working on a surface sensor, the prototype is on my husband's optical bench. This will be able to measure from rough surfaces instead of a retroreflector. Our system has the advantage over those listed in the literature (e.g. SPIE) that vibrations less than the measuring precision do not affect system accuracy. This is a MAJOR problem with interferometric measurement. A spec sheet is available from FASTMAN. 3) In order to achieve 10-5 inch accuracy, you will have to do a significant amount of vibration and temperature control. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Penelope E. Smith PS02@NS.CC.LEHIGH.EDU Department of Mathematics PS02@LEHIGH.BITNET Lehigh University Bethlehem, PA