Band-II Low-Observable Coatings

LPRL provides additives that may be used with many types of paints for giving them low observable characteristics in band II. Current formulas are available for silicone, silicone alkyd, polyurethane, and epoxy based paints. Other varieties of paints may also be rendered low observable in the infrared. For information on how we can help you obtain infrared discretion, please contact LPRL.

In addition to providing additives, LPRL offers prepared coatings that provide infrared discretion in band II (3 -5 mm). LPRL coatings are compatible with a variety of primers, and may be applied using standard technology (e.g. spray gun)

The band II emissivity of these coatings may be tuned from 0.4 to 0.9 and are compatible with radar absorbing materials (RAM), so you are not obliged to choose between radar and infrared discretion - you can have them both!

Band II low observable coatings may be used to reduce the infrared signature of such things as:
  •     tanks
  •     helicopters
  •     the super-structure of surface ships
  •     exhaust covers
  •     tents
  •     camouflage nets
  •     fighter jets
  •     uniforms
The figure above displays the average emissivity between of a selection of available coatings in band II (3 to 5 mm).  In addition, the average emissivity from 3.7 to 4.7 mm is shown, since many detector technologies operate in this range.
One of several independent confirmations of the potential of LPRL IR stealth coatings is shown in the figure at left, which shows the results of a thermal image measurement in band II made by Giat Industries .  The sample shown is an aluminum coupon coated with a standard NATO coating.  In the lower-left quadrant of the sample an LPRL IR stealth coating is deposited over the NATO coating. Since the sample was positioned vertically in an oven, there is a slight vertical thermal gradient present, so comparisons should be made between regions of the sample that are at the same vertical position.  Because the temperature scale is difficult to read, we note here that the apparent temperature difference between the LPRL coated portion of the sample and portion of the sample

coated with the standard NATO coating is approximately 12 degrees Celsius (from roughly 57 to 69 degrees Celsius). This apparent temperature difference increases for higher substrate temperatures. For example, at 150 degrees Celsius, an apparent temperature difference of 16 degrees Celsius is measured between portions of the same sample when one portion is coated with an LPRL coating and the other with a NATO standard coating.

By combining coatings with different emissivities in a pattern, deception may be enhanced. The concept is illustrated at right, where we show how a tank may be coated with a thermal camouflage pattern to match the thermal background.

Compatibility with Radar-Absorbing Materials

To demonstrate the compatibility of LPRL IR coatings with RAM, we present the results of an independent measurement of the reflectivity of a polyethylene film coated with a 250 mm thick coating of LPRL IR material. The experimental arrangement to measure the reflectivity in the range from 8 to 110 GHz is shown below.

The measurements were made at normal incidence. The results are shown below. Three different LPRL coatings were tested, brown, sand, and green. One can see that between 8 and 18 GHz the reflectivity of the PE film remains extremely low even with a coating of LPRL IR paint. The table below shows the results at 35 and 94 GHz.

  35 GHz 94 GHz
     
Brown -17 dB -11 dB
Sand -18 dB -10 dB
Green -17 dB -12 dB
     
Clean PE Film -26 dB -17 dB
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