Dual Blackbody Wide FOV

Features:
Broadband, 3 to 14 microns
Reflective IR target technology for the most accurate and stable differential targets
Controlled background radiance
Folded optical path incorporating reflected background
5º FOV with 36º uniform background
Supports all standard IR system level tests
Manual and automated operation

Reflective vs Emissive
The state of the art has progressed quite quickly over the last decade in the field of IR imagers. Better thermal and spatial resolution have placed greater demands on the test systems used to characterize these imagers. Higher frequency targets that are thermally stable and uniform are needed to properly test the full capabilities of today’s imaging systems. Standard IR target projectors use emissive targets that cannot provide the level of performance required.

Limitations of standard target projectors
Two basic issues exist with emissive targets, the inability to fabricate targets with a uniform emissivity and the uncharacterized and unstable temperature gradients across the target and target holder (target wheel, etc.).

Non-uniform Emissivity
A coating with a high structural content is applied to emissive targets to provide a low reflectance, high emissivity surface. Structural content is a component in creating high emissivity surfaces. In most applications this coating works well and is the industry standard.  High resolution cameras now have the capability to resolve this structure and therefore the non-uniformity it can introduce across the target.
Un-even or inconsistent application of the coating is another source of non-uniformity that limits the performance of the emissive targets.

Temperature Gradients
The standard emissive targets are manufactured with “holes” cut through pieces of thin metal either by an etching process or laser cutting. The thin metal pieces or target masks are then mounted to a target frame. This assembly is then mounted into a target wheel or holder. Thermal mass varies greatly from the center of the target (target pattern) to the edge of the target frame and even more to the edge of the target wheel or target holder. As ambient temperature changes, even by small amounts (±2ºC is very good for a typical laboratory environment) thermal non-uniformities will become apparent in the target. The low thermal mass of the center of the target will change temperature faster than the higher thermal mass of the target frame, target wheel or target holder. The temperature sensor used to monitor the target temperature will not track the temperature gradient in the target and will provide inaccurate temperature measurements to the controller. The net result is a thermally non-uniform and unstable target.  These problems have always been present in the standard target projectors, they were not understood or characterized until recently.
The thermal and emissivity problems inherent in a target projector that uses emissive targets create unacceptable uncertainties when trying to test high performance thermal imagers. Both of these problems are eliminated with the use of the SBIR reflective target technology.

Reflective Focal Plane/Reflective Target Technology
The 13323 utilizes a large aperture, wide field of view off-axis collimator design that incorporates a unique tilted focal plane. The tilt in the focal plane allows the use of reflective targets that reflect a uniform, controlled background (blackbody) into the scene.
Temperature uniformity of the target is no longer important. The reflective target reflects background radiance from a uniform and stable background blackbody to the UUT.
Non-uniformity due to structure on the surface of the target is not an issue with reflective targets. The surface of the reflective target is essentially a mirror and the background blackbody is mounted out of focus in the optical system so the plate is “blurred,” effectively removing any small local non-uniformities.  A thermal sensor is mounted directly in the background blackbody making background energy calibration very easy and extremely accurate.