Different Fresnel Lenses, Different Capabilities - Different TVs

If you have ever looked at the lens of a magnifying glass, you know that it is thick in the middle and tapers down to nothing at the edges. In other words, it is shaped like a lentil, which is where the word lens comes from. It would not be very easy to make a big magnifying glass lens for your RV because it would be thick, heavy and hard to mount.

The thin piece of plastic you are using is called a Fresnel lens. It is flat on one side and ridged on the other. Fresnel lenses we first used in the 1800s as the lens that focuses the beam in lighthouse lamps. Plastic Fresnel lenses are used as magnifiers when a thin, light lens is needed. The quality of the image is not nearly as good as that from a continuous glass lens, but in lots of applications (like your RV), perfect image quality is not necessary.

The basic idea behind a Fresnel lens is simple. Imagine taking a plastic magnifying glass lens and slicing it into a hundred concentric rings (like the rings of a tree). Each ring is slightly thinner than the next and focuses the light toward the center. Now take each ring, modify it so that it's flat on one side, and make it the same thickness as the others. To retain the rings' ability to focus the light toward the center, the angle of each ring's angled face will be different. Now if you stack all the rings back together, you have a Fresnel lens. You can make the lens extremely large if you like. Large Fresnel lenses are often used as ­solar concentrators.

The Fresnel lens is named for its inventor, French physicist Augustin Jean Fresnel. Fresnel studied light and optics in the 19th century.

https://en.wikipedia.org/wiki/Augustin-Jean_Fresnel

https://science.howstuffworks.com/question244.htm

Additional video footage :

https://youtu.be/OmlXR2nsis4

Fresnel lens melting padlock into a puddle
https://youtu.be/YoMjBkKOkPc

@ col mikel COL Mikel J. Burroughs @ ltc stephen LTC Stephen C. @ ltc stephen LTC Stephen F. @ ltc wayne LTC Wayne Brandon @ ltc jeff LTC Jeff Shearer @ maj william Maj William W. 'Bill' Price @ capt tom Capt Tom Brown @ capt marty Maj Marty Hogan @ smsgt doc SMSgt Minister Gerald A. "Doc" Thomas @ tsgt joe TSgt Joe C. @ sra christopher SrA Christopher B. @ msg andrew MSG Andrew White @ sfc george SFC George Smith @ ssg david SSG David Andrews @ sgt jim SGT Jim Arnold @ sgt randy Sgt Randy Wilber @ sgt david SGT (Join to see) @ sgt david SGT David A. 'Cowboy' Groth @ sp5 mark SP5 Mark Kuzinski @ cpl dave CPL Dave Hoover