Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Spitzberg’s mirror-based periscopic design viewed from above. Together, the two mirrors form a ray-shifting device that is similar to a prism in terms of the image shift. In this illustration, the thickness of the spectacle lens is 5 mm and the angular difference of the slanted mirror surfaces is 17 degrees, giving a prism power of about 67Δ, but the field of view is limited to only about 5 degrees.
