Very-low-cost high-speed camera controller and camera simulator for RTLinux for the CHARA array

The CHARA Array at Mt. Wilson uses a PICNIC array camera for fringe detection, connected to a realtime fringe tracking computer running RTLinux. This paper describes the PC- and RTLinux-based camera controller and software that is used to allow high-speed, deterministic, low-latency readout of frames from the camera, as well as a camera simulator that mimics the behavior of the camera. This camera controller is built from commercial off-the-shelf (COTS) PC hardware and uses software running on the free RTLinux operating system, resulting in a very inexpensive camera controller system. The hardware costs for the system, including the PC (although excluding the costs of analog signal interfaces and power supplies), are less than $2000. The controller is capable of reading out arbitrary subimages from the camera, can quickly switch between different readout patterns, and is capable of controlling either CCD cameras or infrared array cameras. Detailed camera timing can be supplied by and/or tuned by the end user, as desired. In addition, a camera simulator unit has been developed. This camera simulator allows the development of camera interface hardware without the risk of damage to the expensive camera. The camera controller described connects to the Niro camera supplied to CHARA by Mark Shure, and the camera simulator mimics the behavior of this camera.