The best way to improve imagery on traditional telescopes is to increase the diameter of the mirror catching light. But this has its limits—perfect mirrors can only be built so large.

A bigger mirror provides two advantages: it catches more light (making fainter objects visible) and it produces a higher-resolution image. If you give up on the first advantage, you can go all in on the second by laying out a handful of small mirrors over a considerable distance. The total mirror area (and therefore light collection) won’t be that great, but the tremendous diameter of the array cranks the resolution up to 11.

That’s the principle behind the Navy Precision Optical Interferometer, a Y-shaped installation with a functional diameter of up to 430 meters.

More details here https://arstechnica.com/science/2018/07/meet-the-telescope-that-may-soon-show-you-an-exo-eclipse