NIR Signatures at Day and Night – Comparison with Different Devices

Night vision devices have become standard on modern battlefields, making camouflage in the near-infrared range an important topic. Whether clothing blends with the surroundings under night vision depends primarily on the environment. Foliage and grass strongly reflect infrared light due to the chlorophyll, appearing bright. However, features like bark and shadows create a varied structure in German forests, requiring an NIR camouflage pattern with sufficient contrast. While solid colors are not considered camouflage patterns, their infrared signature can also be adjusted through different dyes.

Various tools can be used to determine how equipment and clothing will likely appear in the NIR range. This is easiest during the day, as navigating natural environments is simpler in daylight. I have often assessed IR signatures during the day and later confirmed at night that daytime evaluations generally translate well to nighttime signatures. However, it is known that light wavelengths differ in their composition during the day and at night (Source). Therefore, I decided to conduct a simple experiment, capturing images in sunlight and at night using different devices and compare them. My aim is to demonstrate how daytime signatures translate to nighttime camouflage.

Reflection values invisible to the naked eye

For easy visualization, I designed this layout: the left images were taken during the day in sunlight, while the right ones were taken at night under an overcast sky with some moonlight and scattered light reflected by clouds from distant towns. This presentation of the outfit in stone gray-olive illustrates why examining NIR signatures is a relevant topic. The jacket is a softshell from Tasmanian Tiger, the pants are Striker X Gen 2 by UF Pro, the shirt under the jacket is a merino shirt from Armadillo Merino, the shoes are from Salomon, and the beanie is a merino beanie from TACWRK. It is apparent that seemingly identical colors can have different reflection values. When printing or dyeing fabrics, it is usually possible to define the desired values for specific wavelength ranges. Therefore, the material itself plays a secondary role!

The different cameras

Night vision devices amplify visible light and near-infrared light, outputting it as visible light. Act in Black kindly provided me with a NVG, to which I attached my smartphone using an adapter. During the day, a daycap with a small hole enables photography in daylight. For nighttime or low-light photography, this cap is, of course, removed. I took photos using available light and additional IR illumination from a Surefire V1 Vampire.

To photograph the infrared spectrum “normally,” you need a camera with a sensor capable of interacting with infrared. Modern DSLR or digital cameras generally have built-in filters that block UV and infrared light. Removing this filter allows infrared light to reach the sensor. Using an infrared filter in front of the lens blocks the dominant visible light, allowing only light from 720 nanometers onward to pass. However, the sensor is too insensitive to capture much at night, and even during the day, exposure times of several seconds are sometimes required. This method is characterized by high resolution with many details. I have written more about infrared photography here.

Finally, there are affordable digital night vision devices that often include a powerful IR illuminator. These are essentially digital cameras without a blocking filter, making it easy to take photos and videos at day and night. However, their tactical usefulness is limited due to the need for active illumination.

Synthetic jacket in olive

The Carinthia LIG 4.0 is not labeled as NIR-safe by the manufacturer and has a relatively bright signature.

Smock in original Flecktarn

This is a smock from Hexonia in original Flecktarn according to German army specifications (TL). Barely washed. The dark spots give the camouflage pattern significant depth, even under active IR illumination.

Multicam original jacket

Here is a new jacket from Pitchfork Systems in original Multicam camouflage. Not yet washed. Under active IR illumination, it is evident that the camouflage pattern loses some contrast.

Field blouse in Concamo Green

A prototype from GHOSTHOOD made from uniform fabric in Concamo Green. Washed a few times. Here, too, it is evident that the high contrast in the camouflage pattern helps blend into the uneven environment.

Softshell Jacket with EC Paint

I once wrote a post on the topic “Using spay paint to make equipment IR safe?“. In that post, I sprayed a UF Pro softshell jacket in olive with some paint. Or course, I also took a closer look at it. However, the images with the NVG were taken in a different location under indirect moonlight.

Conclusion

Based on extensive experience and the direct evaluation of images, it is clear that NIR signatures of clothing and equipment can also be detected during the day or with digital devices. Minor differences in wavelength composition did not show significant variation in my experiment. In a laboratory setting, finer distinctions could likely be observed, but they currently seem to have little practical relevance.