Maximizing Precision: Understanding Background Subtraction in Ophir Low Power Sensors

Within the field of laser power measurement, precision is paramount. Even the faintest interference from background light or ambient temperature can skew results, leading to inaccurate readings. To combat this challenge, Ophir’s innovative low power sensors employ a sophisticated background subtraction technique, ensuring unparalleled accuracy even in the most demanding environments.

Background Subtraction: A Key to Precision

Photodiode sensors, renowned for their ability to measure incredibly low powers down to picowatts, often face challenges posed by background light in the measurement environment. In some cases, this ambient light can rival or even surpass the power of the laser being measured, threatening the accuracy of the reading.

To address this issue, Ophir’s PD300 series sensors feature a unique dual detector system.
Two identical photodiodes are strategically positioned so that when background light hits both of them equally, no signal is detected. However, when the laser is directed at only the first photodiode, the signal from the laser is isolated and measured. This simple yet ingenious approach allows Ophir sensors to subtract up to 90% of the background light without compromising the accuracy of the laser power reading.

Enhanced Precision with Thermal Sensors

Similarly, Ophir’s 3A and 12A series thermal sensors, designed to measure low powers in the milliwatt range, employ a similar principle for enhanced precision. Within the outer envelope of the sensor, two sensors are positioned, with only one exposed to the laser. This configuration ensures that any ambient temperature drift is effectively canceled out, as the readings from the two sensors align.

Ensuring Accurate Measurements

By utilizing background subtraction techniques, Ophir low power sensors deliver accurate and reliable measurements, even in challenging environments where background interference is prevalent. Whether measuring picowatt-level optical powers with photodiode sensors or milliwatt-level thermal powers, Ophir’s innovative approach to background subtraction ensures that users can trust their measurements with confidence.