Design and implementation of sparse aperture imaging systems

Abstract

In order to better understand the technological difficulties involved in designing and building a sparse aperture array, the challenge of building a white light Golay-3 telescope was undertaken. The MIT Adaptive Reconnaissance Golay-3 Optical Satellite (ARGOS) project exploits wide-angle Fizeau interferometer technology with an emphasis on modularity in the optics and spacecraft subsystems. Unique design procedures encompassing the nature of coherent wavefront sensing, control and combining as well as various system engineering aspects to achieve cost effectiveness, are developed. To demonstrate a complete spacecraft in a 1-g environment, the ARGOS system is mounted on a frictionless air-bearing, and has the ability to track fast orbiting satellites like the ISS or the planets. Wavefront sensing techniques are explored to mitigate initial misalignment and to feed back real-time aberrations into the optical control loop. This paper presents the results and the lessons learned from the conceive, design and implementation phases of ARGOS. A preliminary assessment shows that the beam combining problem is the most challenging aspect of sparse optical arrays. The need for optical control is paramount due to tight beam combining tolerances. The wavefront sensing/control requirements appear to be a major technology and cost driver.

ARGOS testbed: study of multidisciplinary challenges of future spaceborne interferometric arrays

“…The MIT Adaptive Reconnaissance Golay-3 Optical Satellite 12 ͑ARGOS͒ exploits wide-angle Fizeau interferometer technology with an emphasis on modularity in the optics and spacecraft subsystems. The objective of the ARGOS project is to demonstrate the feasibility of a modular architecture for space-based optical systems.…”

Multidisciplinary Control of a Sparse Interferometric Array Satellite Testbed

“…The electronic compass is directly connected to the PC motherboard using a standard RS232 serial port. The PC-DSP FIFO designated for direct communication between the host PC memory and the DSP memory, sends the image processing data 8 such as the centroids of the target from the intermediate CCD, and the compass readings to the DSP controller in real-time.…”

“…The MIT Adaptive Reconnaissance Golay-3 Optical Satellite (ARGOS) 8 project exploits wide-angle Fizeau interferometer technology with an emphasis on modularity in the optics and spacecraft subsystems. Figure 1 highlights the key functional and operational objectives.…”

“…The GUI PC control application sends the reference slew speed and pointing (azimuth and elevation) for a specific target to the DSP while performing real-time image processing from both the intermediate ACS CCD and the main imager (spot-based wavefront sensing 8 ).…”

Analysis of field of view of optical aperture synthesis imaging interferometry

“…Since the cost of monolithic optics increases faster than diameter squared, and mirrors such as the 10 meters groundbased systems and the 2.4 meters Hubble Space Telescope are already at the edge of what is financially feasible, efforts are ongoing to break this limit and this trend by employing breakthrough technologies. A number of solutions are possible and are under investigation [1][2][3][4][5][6][7][8] . It consists of making an array of elementary telescopes (or of mirror segments) interfere, so that the measured data contains some high re There are two widely used image-plane optical beam combination schemes.…”