New electronic read-out design for astronomical detectors

Current-generation imaging electronics are large, heavy, and dissipate a lot of power. These drawbacks are becoming ever more important, particularly for wide-field instrumentation using mosaicked detector arrays. We have recently developed new visual and IR electronic read-out systems aimed at implementation in astronomical cameras. The modular design allows configuration of the electronics for a wide range of currently available IR detectors and CCDs. The new read-out concept can be applied to single or multiple detector systems with up to 144 input channels. The high data-transfer rate, small size (33×13×31cm3), and low heat dissipation make these electronics ideal for use in relatively large focal-plane detector arrays. The first instrument employing the new system is the Panoramic Near-Infrared Camera (PANIC) at the 2.20m (diameter) telescope at Calar Alto Observatory in Spain (see Figure 1). Our main goal was to design a system which could easily be configured to control both IR and visible detectors. The electronics should also be capable of controlling read-out systems associated with different types or a mosaic of detectors. These requirements were met by developing standard hardware boards and an arbitrary-pattern generator. Different types of detectors are supported by exchangeable interface boards. Systems can be extended by adding more standard components, allowing the construction of detector mosaics or simply to increase the number of input channels. Different back planes are used to connect transfer signals to the corresponding system boards. The standard system1, 2 includes detector-protection circuitry and operates with up to four detectors, such as HAWAII2-RG (Rockwell Science) or Fairchild CCD486 devices. It runs on low power (<50W) and is characterized by low read-out noise (2.1 electrons for doubly correlated read-out). Window techniques and on-chip guiding are supported for a number of different read-out modes, including doubly correlated, line-interlaced, multiple end-point, and ‘up the ramp’ sampling. Figure 1. New read-out electronics for the Panoramic Near-Infrared Camera at the 2.20m (diameter) telescope at Calar Alto Observatory in Spain.