When the probe is placed in close proximity to a surface, deviations in the surface cause changes in the chamber pressure that can be directly related to that deviation
The Pneumatic Probe, available from Servotechnic, is an instrument that can measure the contours of a surface without contacting the surface being examined.
The working principles involve passing pressurised air (or any gas) through two orifices and measuring the pressure in the chamber between the orifices.
When the probe is placed in close proximity to a surface, deviations in the surface cause changes in the chamber pressure that can be directly related to that deviation.
The pressure change is measured by a pressure transducer and can be recorded.
The probe is delivered with a console showing contour deviations with digital and analogue display as well as with an electrical output.
The advantages of the product are numerous, says the company: surfaces being measured are not in contact with the probe hence relatively soft materials like aluminium mirrors are not marked.
The surface does not need to be electrically conductive, hence materials such as ceramics or plastics can be measured with equal accuracy to steel, brass or aluminium.
The probe is not just an inspection room instrument: because pressurised gas is used it can operate in an harsh environment such as immersion in coolant whilst machining, hence it is ideal for in-process measurement.
The probe can be used to discriminate to the nanometre level if required.
