---
title: What is 'Excess Gain' in photo sensors?
description: Excess Gain (function reserve) in photo electric sensors
---

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# What is 'Excess Gain' in photo sensors?

## Excess Gain (function reserve) in photo electric sensors

Excess gain is a unitless factor which indicates how much more light reaches the receiver than is necessary for function of the sensor.

Generally, it is expressed as a relative amount, with the required light level = 1.   
The higher the excess gain is, the more reliable is the object detection. The reference material is white, with 90% remission.

If the target is darker, e.g. gray or black, the excess gain is lower and the curve will be different.

Higher excess gain is recommended for contaminated environments.

 

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