That's quite an improvement. But in principle, spatial resolutions of a few tens of nanometers (beyond that you're starting to reach the molecular scale) should he possible using 800-nm light. Pushing the resolution of this lithography down to such a scale will require more work. The problem is no longer optics: it's the photoresists that we use. For reasons that are still being explored- Perhaps the diffusion of the photoresist molecules themselves- attempts to make smaller structures typically result in ill-defined features. If you try to make two features closer together than 175 nm, for example, you can end up curing areas that aren't supposed to be part of the final shape.