Measurement Of Length By Photo Voltice Cell

Measurement Of Length By Photo Voltice Cell

Measurement Of Length By Photo Diode

• A photo diode consists of a p – n junction coated with translucent film .
• The light (radiation) is allowed to fall upon its surface, across the junction.
• The junction is made reverse – biased  with an e.m.f source.
• A reverse current flows nearly linearly  with the intensity of light flux.
• The reverse – biased current flows  through diode is linear function of light intensity, thus to measure  the light intensity level, this current is passed through a precision  fixed resistance R.
• The reverse current devlope proportional voltage  across the R, which is than amplified to desired level by an amplifier.