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Apogee Instruments’ infrared radiometers combine high accuracy, durability, and low cost.


Accurate Measurements
Calibrated to a custom black-body cone with a measurement uncertainty of ±0.2 C from -30 to 65 C when the sensor (detector) temperature is within 20 C of the surface (target) being measured. Radiometers are only sensitive from 8 to 14 µm (atmospheric window) to minimize the influence of water vapor and CO2 on the measurement.


Field of View Options
Four field of view (FOV) options, including: three circular and one horizontal aperture. Custom FOVs available upon request.
Apogee Instruments IRR sensors come in different field of view options.


Rugged Housing
Anodized aluminum body with fully-potted electronics. The radiation shield reduces thermal fluctuations.


Output Options
Analog and digital output options are available. Analog versions include un-amplified voltage outputs. Digital versions include SDI-12 communication protocols. Sensor is also available attached to a hand-held meter with digital readout.


Typical Applications
Plant canopy temperature measurement for use in plant water status estimation, road surface temperature measurement for determination of icing conditions, and terrestrial surface (soil, vegetation, water, snow) temperature measurement in energy balance studies.


The AM-220 mounting bracket is designed to orient sensors at varying angles to satisfy all applications. Bracket can be mounted to a mast or pipe, while accommodating the sensor.

Warranty and Support
All Apogee products are backed by an industry-leading four year warranty and outstanding customer support.


Case Studies

High Throughput Field Phenotyping Infrared Radiometer

High Throughput Field Phenotyping Multi-sensor System
Infrared radiometer measures canopy temperature on a multi-sensor system for high throughput field phenotyping in soybean and wheat breeding.
Read More >



Measuring ground surface temperature to measure snow runoff.
Read More >


Apogee SI-111 Infrared Radiometer monitors surface temperature for WISE

Weather Information Service Engine Project (WISE)
SI-111 Infrared Radiometers measure building surface temperature as part of Weather Information Service Engine (WISE) Project.
Read More >

View all Case Studies >
Need help choosing a sensor?

  Technical Information
Technical Information
Find knowledge base articles, manuals, FAQs, technical support, and more.
What field of view do I need for my application?
Field of View (FOV) is widely dependent on the application. Essentially, you want to select a FOV model that only “sees” what you want the temperature of. A simple FOV calculator for determining target dimensions based on infrared radiometer model, mounting height, and mounting angle, is available on the Apogee website and in the app store.
Can I add additional cable to the sensor?
When sensor is connected to a measurement device with high input impedance, sensor output signals are not changed by shortening the cable or splicing on additional cable or splicing on additional cable in the field. Tests have shown that if the input impedance of the measurement device is 10 M or higher, there is negligible effect on the radiometer calibration, even after adding up to 50 m of cable. Apogee model SI series infrared radiometers use shielded, twisted pair cable, which minimizes electromagnetic interference. This is particularly important for long lead lengths in electromagnetically noisy environments. For information on how to make a weatherproof cable splice click here

We offer custom cable lengths of our high quality cable and splice kits that can be ordered at the time of purchase or at a later date.

Do I need to order a sensor to go with my meter?
No. All Apogee meters (MO, MP, MQ, MI, and MU series) either have sensors built into the meter or attached via two meters of cable. If you order a sensor only (SI, SO, SP, SQ, and SU series) you will need to have your own datalogger (or, depending on the sensor, a voltmeter) to collect information form the sensor.

spec sheets
Specification Sheets



How to Choose an Infrared Radiometer

Brief Overview of Infrared Radiometers

Principles of Surface Temperature Measurement

Lecture 2-Infrared Surface Temperature

Infrared Radiometers

Using Infrared Thermometers for Plant Science Research

Apogee Instruments Meter User Guide



For other temperature sensor options click here.