Low Power Thermopile Sensors, Ophir Compatible

Low Power Thermopile Sensors are the choice for measuring laser beam powers up to 50 Watts. We offer two types that are calibrated for use with Ophir Power Meters. High Sensitivity Thermal Laser Sensors are very low noise and drift sensors that accurately measure low laser powers in the 30uW to 12W range over a wide range of wavelengths. They can also measure low single shot laser energies down to tens of uJ. Low Power Thermal Sensors accurately measure power in the 20 mW to 50 W range as well as single shot laser energy. All low power sensors are calibrated for use with standard ophir power and energy meters. We also offer Medium Power Thermopile Sensors, and Water Cooled Thermopile Sensors for higher power measurement requirements.

Thermopile Sensor Overview

The thermopile sensor has a series of bimetallic junctions. A temperature difference between any two junctions causes a voltage to be formed between the two junctions. Generally, Ophir specifies ±2% uniformity of reading over the surface or better. Thermal sensors are for use from fractions of a milliwatt up to thousands of watts.

Although Ophir thermal power sensors are used primarily to measure power, they can measure single shot energy as well where they integrate the power over time flowing through the disc and thus measure energy. Since the typical time it takes for the disc to heat up and cool down is several seconds, these thermal sensors can only measure one pulse every several seconds at most. Thus they are suitable for what is called “single shot” measurement. Although the response time of the sensor discs is slow, there is no limit to how short the pulses measured are since the measurement is of the heat flowing through the disc after the pulse.

Ophir has developed several types for different applications, such as long pulses (0.1-10ms), short pulses (<1µs) and continuous radiation. Absorbers optimized for long pulses and CW are characterized by thin, refractory materials, since the heat can flow through the coating and into the disc during the pulse. On the other hand, heat cannot flow during short pulses, and all the energy is deposited in a thin (typically 0.1µm) layer near the surface. This causes vaporization of the surface which ruins the absorber. Instead, a volume absorber that is partially transparent and absorbs over a distance of 50µm -3mm is used. This spreads the heat over a larger volume allowing much higher energies.

Compaible Power Meters

High Sensitivity Thermal Sensors

Low Power Thermal Sensors