Four bar patterns or "targets" are the most commonly used standard in determining the performance of infrared imagers. A series of pattern sizes and temperature contrasts are used to determine the minimum resolvable temperature of the imager at various frequencies. As the target bars get smaller, (i.e. higher frequency), a higher temperature contrast is required to resolve the bar pattern. See the graphic below. The highest frequency that can be resolved is referred to as the cut off frequency or the Nyquist limit.

For ease of testing the targets are frequently mounted in either a manual or motorized target wheel. Wheel targets are normally mounted in a round target holder that permits rotation of the target to test anti-aliasing. Individual targets are normally mounted in a square target holder.

Besides standard four bar targets, EOI can also provide reflective or other specialized targets for specific test requirements. Contact EOI with your requirements.

Four Bar	Multiple 4 Bar	Slit - Horiz, Vert or at an Angle	Bore Sight Alignment
Edge Determination	"Pin Cushion" or Distortion	Custom Tactical Targets