You can “optically contact” bits of glass together and it will hold very well if done properly, this is what holds etalons together in solar telescope filters amongst other things. Getting it to work is a “black art”, the surfaces need to be very flat and smooth (same shape) and perfectly clean and then you press/slide/wiggle them together. You can see interference fringes from very closely spaced glass surfaces which then disappear at the contact area.
Had my colleague stick some old “crappy” flat bits together for a test recently. Need very flat (better than lambda/10) and very smooth. I doubt you could polish two non flat surfaces this good reliably. If the composition was different then the thermal expansion would likely mismatch and the joint fail. Mine were fused silica on both sides.
Peter
Had my colleague stick some old “crappy” flat bits together for a test recently. Need very flat (better than lambda/10) and very smooth. I doubt you could polish two non flat surfaces this good reliably. If the composition was different then the thermal expansion would likely mismatch and the joint fail. Mine were fused silica on both sides.
Peter
