Free sample pair - glasses with diffraction grating

[Astroscanner]

When I read elsewhere about people shining lasers thru diffraction grating I remembered that years ago I got some free pairs of 3D glasses from a company that also included some speciality glasses that used diffraction grating, I shined my laser thru the lens recently and it put evenly spaced dots all over the place so I asumed it used diffraction grating on that pair. The glasses are cardboard frame with thin plastic lens, but they work and they were free !



I just checked to see if any places still offered the free glasses, they do, but now they do ask that you send a self-addressed stamped envelope to get your free pair. (which is understandale if they had gotten a lot of requests in the past for free samples and the postage started adding up)



(so technically it is no longer totally free, it now costs sending a self-addressed stamped envelope, but that is understandable)



For your free sample pair they let you choose from several types, I believe the Fireworks glasses is probally the diffraction grating type.



(click on the link below to see the types you can choose from as well as the address to send a self-addressed stamped envelope)



Free 3D Glasses - Get a Free pair of 3d glasses from Rainbow Symphony Inc.