Use interferometry to improve astronomical observations. Astronomical interferometry uses two comparatively small telescopes to get high-resolution observations instead of a single very expensive telescope. Each of these telescopes is a simple interferometer.
Exploit the rotation of the Earth to move the interferometer array. Interferometry can make use of a single array of stationary telescopes on the ground. This allows each telescope to make observations along different tracks over time.
Conduct very long base-line interferometry by making use of the Earth's orbit about the sun. Take two observations from the same telescope six months apart. By comparing these results, you can effectively perform interferotmetric studies that use a baseline distance of 2 astronomical units (186 million miles).
Observe very long wavelengths in interferometry. Longer wavelengths are generally better for interferometric studies because it's easier to measure the phase information of these types of waves. The first astronomical interferometers were performed on radio waves.
Make use of improved technology to study electromagnetic radiation with shorter wavelengths. The speed of the correlators, which compare the two sources of light, has improved to the point that interferometry may now be performed on radiation with wavelengths shorter than a millimeter.