Performance Sensitivity To Telescope Aperture

9010-039

The performance of any directed (beamed) telescope system is a very sensitive function of telescope aperture size, particularly in the visible regime. This can be seen as follows for a symmetrical telescope system with mirror diameter "d":

Thus, the performance of a small visible wavelength telescope could be proportional to d⁸. This means that a factor of 10 increase in the size of the mirrors could lead to a change in recovered SNR of between 60 and 80 dB, depending on Planckian radiation levels and bandwidth. Clearly, the performance of a symmetrical optical interstellar communications link, particularly one operating in the visible region of the spectrum, is so sensitive to mirror size assumptions, that a small change in mirror diameter produces a drastic change in system performance. Compared to a 10 m diameter mirror system, 10 cm diameter mirrors could reduce the system performance by 160 dB!