I need to make a full aperture lens that is thicker than the glass available to me.
So I suppose one solution is to fuse two thick sheets of plate glass together in a kiln. This works well for a front surface mirror, but I wonder about a refractive element where the fused boundary has light moving through it. Does anyone know if the fused boundary zone will be a source of significant aberrations?
I ask, because I am trying to assemble a telescope that calls for a lens thicker than any affordable glass, but less than twice as thick as what I have.