Noise Equivalent Temperature Difference

If you are buying an infrared camera, or anything really, you want to know about specifications so that you can compare different products objectively and find the one that is best for you. If so, you are going to come across the noise equivalent temperature difference (NETD). It is also generally referred to as thermal contrast and usually expressed in milli-Kelvin (mK).

Thermal contrast is a primary specification of infrared cameras that determine their suitable uses. It describes how well the thermal imaging sensor is able to distinguish the differences in thermal radiation in an image. The smaller the value of the thermal contrast, the more accurate the instrument. An infrared camera with 120mK would produce more accurate images compared to another camera with 150mK NETD.

Another effect of smaller NETD is better image quality. A smaller value means smoother transition between different temperatures which produces less noise in the image. A difference of 30mK in NETD makes a significant difference in image quality.

The NETD can be affected by several factors. Some infrared cameras come with multiple calibrated temperature measurement range. The amount of noise in the image can vary depending on the range chosen and the temperature of the object. What is important to keep in mind is that as long as the image has significant thermal contrast and the temperature of the object is significantly higher than the background, the accuracy of the measurement should not be affected.

Infrared camera for hobbyists

When it comes to infrared cameras, hobbyists and pros have virtually the same needs. That is a precise instrument that is easy to use. The only real difference comes down the budget. Professional applications tend to demand some extras like weather sealing and shock-proof features. Professionals need an infrared camera that can be used out in the field and in punishing conditions.

For hobbyists whose instruments rarely leave the garage, there are some good choices on Amazon for the budget-friendly camera with prices ranging from 200 to 500 USD like the FLIR TG165. The TG165 is a perfectly capable infrared camera with an operating temperature of -25 to +350 degree Celsius and sensitivity of 150 mK. I used it for general applications like checking insulation and some automotive work at home. I was even able to spot a raccoon up the tree 50 meters away. A micro-SD card storage allows for easy saving and transfer of data.

I replaced the TG165 with Testo 865 which I got a good deal. The 865 is normally priced at around 1,150 USD but I got mine for half that. After having used the 865 for over a year, I would say it is good value even at full price. With a thermal sensitivity of 120 mK, the 865 offers better measurement accuracy. It also came with calibration certificate, power supply, battery, software, guide, and bag. TG165 came in bare.

The 865 has narrower operating temperature, from -20 to +280 degrees Celsius, compared to the TG16. However, since I don't really work with temperatures beyond its operating temperature, the Testo 865 is perfect for me.

Temperature instruments for inspections

Regular and thorough inspections keep operations running smoothly. It improves efficiency and maximizes the productivity of any industrial enterprise. Inspections are also necessary for promoting workplace safety. In order to accomplish all these intents, inspections must be done right.

Tools are used to aid in inspection make tasks easier, safer and precise. Temperature instruments are used for inspection applications that involve engines and other machines that generate heat.

There are many kinds of temperature instruments. The two most-commonly used temperature instruments for industrial inspection applications are the infrared camera and infrared thermometer. These two instruments are very similar in how they take measurements.

As you can surmise from their names, both instruments use infrared radiation to take readings. They also operate very similarly. You hold the instruments like you would hold a handgun and aim it at the object or surface you want to take readings from. Pull the trigger and you get your readings.

The difference is the way they provide readings. An infrared thermometer provides measurement readings of a single point on a display screen. An infrared camera generates a thermal image. Between the two instruments, the infrared camera provides extensive thermal readings of all surfaces and objects captured in the image. Instead of taking multiple readings with an infrared thermometer, you can take a single snap with the camera and you will have all the information you need.

However, the advantages of an infrared camera come at an expensive price. This too is important to consider.