What are the limitations of this technology?

Although new optical interferometry technology has great potential benefit for the study of astronomy, there are several possible complications. Hajian and Armstrong note two significant problems involved in producing high resolution images of stars with optical interferometry -- turbulence in the earth’s atmosphere as well as constraints on interferometer response time. Turbulent irregularities distort light waves as they propagate through the atmosphere, causing the apparent position of a star in the sky to move around. This motion can cause the two beams in an interferometer to interfere irregularly or not at all. Additionally, turbulence creates a changing delay to each beam, making it difficult to ensure both beams reach the sensor simultaneously to create the appropriate interference pattern. To compensate, astronomers have employed adaptive optics, such as those found in the Keck Interferometer and Very Large Telescope Interferometer, in which sensors record incoming wave distortions and trigger rapid response tilting mirrors to adjust for the problem. As the number of telescopes involved in the interferometer system increases, more complex optics are necessary to compensate for a greater number of beams involved in creating interference patterns.

There are other limitations involved in the construction and use of optical interferometers. First, light from the object being studied must be gathered within 10 milliseconds to ensure that the image does not moved significantly. In addition, the interference pattern itself must be detected within a few milliseconds to avoid smearing from the aforementioned turbulence. The technology necessary to control for these complications includes high-speed photodetectors with high-level storage and processing capabilities and frequency-stabilized lasers to measure continually changing delay line lengths.