Detector and FPA Testing

The FPA Test Set (FPATS) interface to the detectors under test (DUT’s) is via a custom pedestal plate which provides both a conductive heat path to both the individual DUT’s as well as the field of view limiting aperture plate. This custom pedestal plate protrudes through the customer provided DUT interface printed circuit board (PCB) and makes physical contact with the rear of the DUT packages and the aperture plate when the FPATS is in the closed position. The pedestal plate is mounted to the ambient source plate and its temperature is actively driven by this subsystem.

Ambient Source Assembly
The ambient source assembly includes an SBIR EXLT-08 extended area blackbody modified to interface to the Pedestal Plate that mates with the back side of each of the nine FPA’s. The temperature of the blackbody is precisely controlled. The pedestal plate is tightly coupled to the blackbody and provides the thermal transfer to the FPA’s. The FPA has temperature sensor that is monitored by the customer supplied PCB. The interface plate design will be determined by the specific FPA configuration and layout of the PCB.

Aperture Plate Assembly
The Aperture Plate provides a uniform background and f/1 cone limiting aperture for each of the FPA’s. The Aperture Plate is thermally coupled to the Pedestal Plate when the system is closed and locked. The temperature of the Aperture Plate is monitored via a temperature sensor that is connected to the Ambient Source Controller. The temperature of the Aperture Plate will be close to the temperature of the ambient blackbody but is dependent on the final design of the Aperture and Pedestal Plates. The Aperture Plate assembly also includes a set of 18 high temperature point sources, two for each aperture, that are used for foreign object detection. The sources are turned on and off via the Ambient Source Controller.
The design of both the Pedestal Plate and Aperture Plate is driven by DUT requirements. Knowledge of the DUT chip packaging and holder PCB, as well as the required DUT field of view (FOV) is necessary to complete the design of both of these plates. One set of these replaceable custom designed plates is included with the SBIR FPATS.

Scene Source Assembly
The scene source assembly is an SBIR EXLT-08 extended area blackbody modified to work in the FPATS. The Scene Source uniformly illuminates the DUT’s through the limiting Aperture Plate. With the exception of the DUT view, the Scene Blackbody is thermally isolated from the remainder of the FPATS system. The temperature of the scene is closed loop controlled and completely independent of the Ambient Subsystem.

Housing Assembly
The FPATS is a standalone system approximately 3ft x 3ft x 4ft and weighs approximately 250 lbs. In the safety locked open position, there is easy access for loading and unloading the DUT PCB. In the mechanically latched and switch monitored closed position a seal is formed between the Ambient Source Assembly, Aperture Plate Assembly, and Scene Source Assembly. This cavity is is designed to be continously purged with dry nitrogen when the system is closed and the sub-systems are turned on.