I have three glass lenses from a large projection lens which I would like to turn into a refractor objective. They are 5" diameter. I have a good idea what the glass types are, but I want to be sure before I start to grind any glass.

I am planning on measuring the focal lengths at various wavelengths to I can know the dispersion of each glass. I have no light sources or filters which are acurate enough to do this with. So, I thought that I could use a street light which emits only certain wavelengths of light. There are High Pressure Sodium and Metal Halide lamps commonly used.

I need to find out what wavelengths are emitted by these lamps. I have not been able to find out which wavelengths are in these lamps. I did not find it on GE`s site or Sylvania`s either. Do you know were I can find out? Thanks

• RE: I need help identifying glass! - Pereira - August 3, 2000 - 12:37 UTC
• RE: I need help identifying glass! - bobmay - August 3, 2000 - 16:47 UTC
  • RE: RE: I need help identifying glass! - Steve - August 4, 2000 - 03:22 UTC
    • RE: RE: RE: I need help identifying glass! - bobmay - August 4, 2000 - 16:11 UTC