Shadow Technique Improves Measurement of Micro Holes June 2,
2005 Contact: Gail Porter Sometimes seeing a shadow can be as
good or better than seeing the real thing. A new measurement
method* developed by researchers working at the National
Institute of Standards and Technology (NIST) is a case in point.
The method uses the shadow cast by a small glass probe to infer
the dimensions of tiny, microscale holes or other micrometer-
sized components. The technique may provide an improved quality
control method for measuring the interior dimensions of fuel
nozzles, fiber optic connectors, biomedical stents, ink jet
cartridges and other precision-engineered products. Designed to
be implemented with the type of coordinate measuring machine
(CMM) routinely used in precision manufacturing settings, the
method uses a flexible glass fiber with a microsphere attached
on one end. The glass probe is attached to the CMM's positioning
system, inserted into the part to be measured, and
systematically touched to the part's inter