: Dear friends; : I have heard that there is a technology which constructs telescope quality objective lenses from crown glass and special chemical liquids (the chemical liquid is of course used as a refracting media). I am looking for information on this technology . I'll be pleased if anybody help me on this subject . Thanks in advance. Look up Megalux for a start. I found them by searching for +optical +fluids. I stopped my search after finding this first reference.