ABSTRACT

Optical methods of pressure measurement include the deformation measurement of elastic members like diaphragm and cantilever, photoelastic method, acousto-optic effect, pressure sensitive paint, and pressure-dependent thickness change. A typical pressure sensitive paint (PSP) consists of a luminescent molecule (luminophore) in an oxygen-permeable binder to physically adhere the luminophore to the surface of the test specimen. Pressure measurement with PSP depends on the sensitivity of the specific luminophore to the presence of oxygen molecules or on the partial pressure of oxygen. It is obvious that there could be two different schemes for the measurement of partial pressure of oxygen. In one scheme, the luminescent intensity with respect to a reference value is to be measured, whereas in the other scheme, the decay time is to be measured. In the experimental scheme in which decay time is to be measured, the PSP-coated object is scanned with an unexpanded narrow beam and a photodetector with a suitable filter in front is used.