The two Keck 10 -meter telescopes, separated by a distance...

The two Keck 10 -meter telescopes, separated by a distance of 85 meters, can operate as an optical interferometer. What is its resolution when it observes in the infrared at a wavelength of 2 microns?
a. 0.01 aresec
b. 0.005 arcsec
c. 0.2 arsec
d. 0.05 arcsec

Key Concepts

Baseline in Interferometry

In the context of interferometry, the baseline is the distance between individual telescopes. It plays a critical role in determining the resolution, as the effective aperture of the interferometer is analogous to the distance between the telescopes. A larger baseline leads to a finer, or higher, angular resolution because it samples larger spatial frequencies.

Wavelength Dependence in Resolution

Angular resolution in interferometric and diffraction-limited systems is directly proportional to the wavelength of observation. This means that observing at longer wavelengths, such as in the infrared, results in lower resolution compared to shorter wavelengths under the same physical baseline conditions. Calculating this resolution involves dividing the wavelength by the baseline and converting the result into appropriate angular units.

Optical Interferometry

Optical interferometry is a technique that combines the light collected by multiple telescopes to simulate the resolving power of a much larger telescope. This method enhances the angular resolution beyond what a single telescope of comparable size could achieve by taking advantage of the interference between light waves from the same source detected at different locations.

Diffraction-Limited Resolution

The concept of diffraction-limited resolution refers to the smallest angular separation at which two point sources can be distinguished, determined by the wavelength of light and the size of the aperture or effective baseline. This limitation arises due to the wave nature of light and defines the sharpest image possible under ideal conditions.

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