It makes sense, but not what I was expecting

For parts for a simple optics demo, I searched amazon for lead glass. The first thing that came up was lead glass glasses--to protect eyes from x-rays. It looks like a good pair with .75mm lead equivalent is about $200--well worth the investment if you deal with x-rays a lot.

You'd not think you could see through lead, but lead glass can have a surprising amount of lead in it and still be quite transparent--36% of lead oxide was traditional, 40% possible. By mass. Bricks of lead glass were used in physics experiments back in the day--gammas and electrons would interact with the lead, producing showers of particles, which would produce Cerencov light in the high refractive index glass--and you could just glue a light guide and phototube on the end, because little light would be lost.