This is done using a technique called interferometry, which merges the beams of light in a way that simulates the sharpness (though not the brightness) of the images that would be obtained from a telescope whose mirror was 200 metres across.

ECONOMIST: Beneath the Southern Cross I stand | The

To measure the refractive indices of different parts of a cell they use a technique called interferometry, which involves splitting a beam of light in two.

ECONOMIST: Microscopy