PRECISION HOLOGRAPHIC OPTICAL PROBE FOR DISPLACEMENT AND SURFACE MEASUREMENTS

We describe a new precision displacement probe-the precision holograph ic optical probe (PHOP)-with the use of double holographic optical ele ment (DHOE) technology. It is a novel noncontact method for the measur ement and inspection of displacement and surface quality control. To i mprove the measurement resolution and linearity, the differential meth od for the PHOP is introduced. Infrared DHOEs are made by using a comp uter-generated hologram method. Mathematical models have been develope d to analyze the performance of the probes. Computer simulations and e xperimental results have been obtained, showing sensitivity on the ord er of nanometers for these probes. The complexity and the size of the probes can be significantly reduced. They are both compact and inexpen sive.