A series of concentric grooves on a flat, thin piece of plastic makes possible a large diameter, lightweight and inexpensive lens with a short focal length. Each groove acts as a minute refracting facet capable of bending light, thus giving greater transmittance than a conventional lens of the same focal length. Material is Acrylic with transmission of 92% throughout the visible spectrum. Maximum service temperature is 80°C. Rolyn fresnel lenses are corrected for spherical aberration.
