optical indicator

optical indicator

[′äp·tə·kəl ′in·də‚kād·ər]
(engineering)
An instrument which makes a plot of pressure in the cylinder of an engine as a function of piston (or volume) displacement, making use of magnification by optical systems and photographic recording; for example, the small motion of a pressure diaphragm may be transmitted to a mirror to deflect a beam of light.
References in periodicals archive ?
Four optical indicators measure flow, quantity, milking time and milk quality at each teat.
The Shelter Roof's safety features include photo switch for automatic speed reduction, optical indicators and sensors which stop the vehicle automatically at the touch of the aircraft.