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 BB type is employed in most of the models and has an excellent constant absorption throughout the responsive wavelength range. 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 Physics

A thermopile consists of a number of the thermocouple junctions (typically 20 to 120) in series. All the “hot” junctions are placed close together to collect the radiation. Thermopiles have time constants ranging from below 50 ms, in small sizes with metal oxide blackening to more than a second for larger thermopiles made with individual wire junctions backing up a highly absorbing black disk. Thermopiles exhibit no flicker, 1/f, noise, since no current bias is needed to operate them. Highly sensitive measurements can be made from DC to the few Hz frequency response limit of a particular device.

Schematic drawing of a thermopile detector.

Ideal for High Power Measurement

Newport’s new 919P Thermopile Detector Series provide a full range of sensors to meet the power measurement needs for CW or pulsed lasers. They offer broadband, spectrally flat response, with the maximum power range up to 5000 Watts.

NIST Traceability

Each 919P thermopile sensor include 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.

Cross Reference Chart for Legacy 818P Series Thermopile Sensors

Legacy 818P Model Replacement 919P Model
818P-001-12, 818P-001-12NIR 919P-003-10
818P-015-19 919P-010-16
818P-010-12, 818P-020-12 919P-020-12
818P-030-19, 818P-015-17W, 818P-030-17W 919P-030-18
818P-040-55, 818P-040-50W, 818P-050-50W 919P-040-50
818P-015-18HP, 818P-030-18HP 919P-050-18HP
818P-040-25, 818P-050-17W 919P-050-26
818P-100-25, 818P-110-19, 818P-150-19 919P-150-26
818P-100-55, 818P-250-25, 818P-300-25 919P-250-35
818P-300-55, 818P-400-55, 818P-500-55 919P-500-65
818P-3KW-65, 818P-3KW-100 919P-5KW-50

Please note that the 919P Series Thermopile Sensors are intended to replace the 818P Series Sensor. Also note that both the series are incompatible with certain optical power meter models. The following table provides the recommended replacement 919P models for each 818P series model. Even though the recommended models have the closest specifications as the obsoleting ones, however, not identical. The user must carefully compare each specification.

Flexible Fiber Adapters

Detector Model

Required Mounting Ring





919P-050-26, 919P-150-26




919P-020-12, 919P-050-18H

Fiber adapters not mountable

In order to accommodate various aperture sizes, we provide adapter rings as well as the fiber adapters. Refer to the table for the corresponding adapter ring for each detector model. Note that certain models do not accept a fiber adapter.

Sensor Selection for Lasers

If you already own a laser from Newport and Spectra Physics, check our Optical Sensor Selection Guide to see the recommended sensor each laser product.