We describe three novel optical fiber probes, all based on the focused-beam reflective principle, to measure displacement, form, and surface topography, respectively. Each depends on deriving twin
displacement/optical output characteristics that may be resolved by difference/sum referencing. The displacement sensor adopts twowavelength operation using a zone plate to give opposing displacement/output characteristics. The device is noncontacting, and a resolution of better than 0.1% of span is anticipated. A 3-D optical touchprobe has been built for use with coordinate measuring machines. A mathematical model has been generated that relates output to stylus movement, and the model has been verified experimentally. A resolution of 0.1 μm in the x-y plane and 1.0 μm in the z direction is achievable. A further noncontacting probe has been developed for the measurement of surface topography whose output shows low dependency on surface reflectance. A mathematical model has shown good correspondence against a wide range of surface compositions and textures; a resolution of better than 1 μm is foreseen. Proposals are made for industrial implementation of all three probes.
Ronald C. Spooncer,
Barry E. Jones,
"Optical fiber displacement sensors for process and manufacturing applications," Optical Engineering 31(8), (1 August 1992). https://doi.org/10.1117/12.58847