Steps for Selecting a Thermal Camera, Requirements Table Broken Down by Professions

Thermographic devices suitable for contactless temperature measurement (infrared cameras with thermographic capabilities) have undergone rapid development in recent years. Considering that these devices appeared just 50 years ago, today they have grown into one of the most well-known and versatile inspection tools, so we should not be surprised by the diversity of the market offer (manufacturers, types). For a customer planning to purchase a thermal camera, it is no longer the lack of types that meet their needs, but rather the overwhelming variety of options. Therefore, it is time to review the development and types of these instruments from a professional perspective, and organize the current offer based on some important technical parameters. The measurement technology implemented in the cameras and the accessories available determine the application area of the device, as well as the expected measurement accuracy and the quality of the thermal image.

Steps for Selecting a Thermal Camera

The sequence of selection criteria for choosing a thermal camera that meets the specific thermographic measurement task, based on the current range of thermal cameras, is as follows:

0) Installed or Mobile?

A fixed thermal camera is not suitable for handheld measurements because it lacks a battery, controls, or its own display (carrying a continuously connected notebook is impractical). A portable thermal camera is not suitable for fixed tasks where cooling/heating, moisture, and dust protection are required, as protective covers of this kind are typically only available for fixed types.

1) Wavelength Range

A long-wave range is not suitable for measuring objects with high emissivity in the mid-wave range or when there is glass (or other materials that do not transmit long waves) between the object and the thermal camera. A mid-wave range is not suitable for measuring low-temperature objects, measuring from large distances (several times greater than 10 m), or when objects with acceptable emissivity in the long-wave range are present between the object and the thermal camera.

2) Detector Technology

Considerations: wavelength, frame rate - Use a bolometer/microbolometer sensor if a long-wave device is needed and a maximum frame rate of 50/120 Hz (or up to 240 Hz for special thermal cameras) is sufficient. (Note: For freehand thermal camera use to avoid problems caused by motion, a minimum frame rate of 50 Hz is required.) Use photon detectors if measuring in the mid-wave range (e.g., through glass) or if a frame rate above 50/120 Hz (or in exceptional cases 240 Hz) is needed. (Note: Photon detectors are significantly more expensive than bolometers and also require cooling, which depending on the technology, may impose a limitation on the lifespan.)

3) Thermal Resolution

Consideration specific to the task - Critical for checking boilers and furnaces, assessing mechanical or electrical equipment where fault locations/thermal phenomena involve large temperature differences. Important for searching for moisture/leaks; assessing insulation, fire-resistant linings (wear). Generally the most crucial parameter for biological or material testing measurements. (Note: Improved thermal resolution provides sharper, clearer, and more recognizable thermal images. In building thermography, the number of days/applicable temperature differences between indoor/outdoor environments depends on thermal resolution, which is one of the most important return factors.)

4) Temperature Measurement Range

Consideration specific to the task - Particularly important for measuring low-temperature objects.

5) Number of Pixels

- Absolute minimum: 160 x 120 pixels (effective operation with fewer pixels is hardly possible) - Recommended minimum: 256 x 256 or 320 x 240 pixels - Economical: 384 x 288 pixels - Professional: 640 x 480 or 640 x 512 pixels - Current peak: 1024 x 768 pixels - Favorable solution: quadrupling pixels with microscan (up to 1280 x 960 or 2048 x 1536 pixels) (can be used with or without a stand; not interpolation calculations, but real measurement points) (Note: The more pixels the camera has, the more details become recognizable in the image or the larger object (equipment) can be examined at once with appropriate resolution.)

6) Geometric Resolution

- Consideration specific to the task - Preferably choose a thermal camera with interchangeable lenses for various tasks to ensure the appropriate geometric resolution is always available. A favorable solution without interchangeable lenses: quadrupling pixels with microscan, improving the geometric resolution to 2/3 of the value specified for the same detector/optics setup.

7) Special Capabilities - Rapid internal storage of thermal image sequences without a PC - Remote control, live data transmission - Interchangeable lenses, special filters

Selection Criteria for Task-Specific Thermographic Devices

Professional Field	Spectral Range	Technology	Calibration Range	Number of Pixels	Geometric Resolution	Thermal Resolution	Frame Rate	Recommended Functions/Accessories
Building Thermography	8...12 µm	Bolometer (photon detector is also good but expensive)	min. -20°C ... 100°C better from -40°C (upper limit approximately)	min. 320x240 better 384x288 recommended 640x480 peak 1024x768	min. 1.5 mrad better 1 mrad + telephoto lens	min. 80 mK better 50 mK best 30 mK (30mK: can be measured over several days = better return)	manual capture: min. 50 Hz	- selectable color scale - autofocus - telephoto lens - wide-angle lens
electrical equipment measurements	8...12 µm	bolometer (photon detector also good, but expensive)	min. -0°C ... 150°C better -20°C ... 250°C	min. 160x120 better 320x240 recommended 384x288 or 640x480 peak 1024x768	min 2 mrad better 1.5 mrad best 1 mrad	min. 120 mK better 80 mK best 50 mK	manual capture: min. 50 Hz	- selectable color scale - autofocus - digital video camera - composite imaging - digital sound recording
mechanical equipment measurements	8...12 µm	bolometer (photon detector for moving objects, fast processes)	min. -20°C ... 250°C better -40°C ... 400°C	min. 160x120 better 320x240 recommended 384x288 or 640x480 peak 1024x768	min 2 mrad better 1.5 mrad	min. 120 mK better 80 mK best 50 mK	manual capture: min. 50 Hz moving objects: >>50 Hz	- selectable color scale - autofocus - burst mode - difference mode - digital video camera - composite imaging - digital sound recording
medical (biological) measurements	8...12 µm	bolometer (photon detector also good, but expensive)	min. -20°C ... 50°C better -40°C (upper limit approximately)	min. 320x240 better 384x288 recommended 640x480 peak 1024x768	min. 1.5 mrad better 1 mrad	min. 50 mK better 30 mK best 10 mK	manual capture: min. 50 Hz	- selectable color scale - autofocus - burst mode - difference mode - high image homogeneity - composite imaging
glass-related measurements	3...5 µm (8...12 µm only for glass surfaces)	photon detector	min. 100°C ... 1200°C better 0 ... 2000°C	min. 320x256 recommended 640x512 peak 1280x1024	min 2 mrad better 1.5 mrad	min. 120 mK better 80 mK	process-dependent (typical >>50Hz)	- selectable color scale - autofocus - burst mode - difference mode - special filters - macro lenses - microscope lenses - protective windows
microelectronic measurements	8...12 µm (3...5 µm also good, but expensive)	bolometer (photon detector for fast thermal processes)	min. -0°C ... 150°C better -20°C ... 250°C	min. 320x240 better 384x288 recommended 640x480 peak 1024x768	min. 1.5 mrad recommended 1 mrad better 0.7 mrad +special lenses	120 mK better 80 mK best 50 mK	> 2 x process frequency (min. 50 Hz)	- selectable color scale - autofocus - burst mode - difference mode - macro lenses - microscope lenses - pixel-wise emissivity correction - fast thermal imaging
metallurgical measurements	8...12 µm or 3...5 µm	bolometer or photon detector	min. 300°C ... 1200°C better 0 ... 2000°C	min. 160x120 better 320x240 recommended 384x288 or 640x480 peak	min. 320x240 recommended 384x288 peak 640x480 1024x768	min. 0.3 mrad recommended 0.2 mrad peak 0.1 mrad	120 mK peak 80 mK best 50 mK	handheld recording: min. 50 Hz	- selectable color scale - autofocus - "large" telephoto lens - digital video camera - composite imaging - digital sound recording - GPS data management