Thermopile Sensor, 150 W, 26 mm, 0.19-11 µm, Fan Cooled

The 919P-150-26 Fan Cooled Thermopile Sensor is a general purpose thermal sensor measuring optical power up to 150 W. It's spectrally flat coating covers the wavelength range 0.19 - 11 µm (BB type coating). It has an active diameter of 26 mm and can measure continuous optical power from 50 mW to 150 W and single shot energy from 20 mJ to 100 J. It has a 1/4-20 tapped hole for post or plate mounting. The product includes a 2.25 inch long 1/2 inch diameter post with a 1/4-20 tapped hole on both ends.

Constant Responses over Broad Wavelength Range

The thermopile detector's response to the input laser beam is characterized by its absorption. We use two different types of coating in the sensor. The broadband BB type is employed in most of the models and has an excellent constant absorption throughout the responsive wavelength range. Majority of the 919P series detectors employ the BB type, and you can measure light with the wavelength up to 11 µm. The PF type is employed in the mode 919P-050-18HP , which is specially designed for high energy density pulses.

Extensively Tested for Damage Threshold vs. Pulse Width

The 919P series thermopile detectors have been extensively tested for the damage threshold with a variety of lasers. You can trust our specifications and have your mind at ease.

Thermopile Sensor Power Measurement

Thermopile optical power sensors are based on thermocouples. A thermocouple consists of two dissimilar metals connected in series. To detect radiation, one metal junction is typically blackened to absorb the radiation. The temperature rise of this junction with respect to another non-irradiated junction generates a voltage. This effect is the basis of all thermocouple temperature sensors. The thermocouple materials used in thermopiles are usually bismuth and antimony, which have a relatively high thermoelectric coefficient. An individual thermocouple typically produces a low output voltage, which results in a low detectivity and limits its use as a sensing device. So, one way to increase the output voltage is to connect many thermocouple junctions in series. All the “hot” junctions are placed close together to collect the radiation. The typical operation of a thermopile is shown above. The thermopile disc consists of a circular array of thermocouples. The optical radiation is absorbed by the disc generating the output voltage. The heat on the disc spreads radially across the thermopile on the reverse side of the disc where it is transferred to a heat sink. These devices are quite sensitive in the IR due to their broadband absorption. Due to the heating and cooling processes, the response time of a thermopile is quite slow, typically on the order of seconds. Due to this time constraint, thermopiles are used exclusively for measuring the power of CW or quasi-CW radiation sources.

NIST Traceability

Each 919P thermopile sensor includes a DB15 connector and internal EEPROM for storing factory calibration data. Most sensors are calibrated at three different wavelengths at 532 nm, 1.064 µm, and 10.64 µm. Calibration of the thermopile detectors is recommended annually to assure NIST traceability.