Old Edmund Scientific stock. Edge thickness is 12mm, center thickness is 15mm. Cemented doublet in great original condition but not visually color corrected as is. Has a bluish/purple anti-reflective coating. We have quite a few of these if you want to incorporate them into your project! These work well with other lenses to make exceptional color corrected eyepieces. Unused. We think these were made to be the field lens for one of their famous RKE telescope eyepieces. The RKE design included a double convex eye lens and a special doublet field lens. See attached photos for the design info. You can do some fun experimenting with these.
