As I understand the Fresnel Lens, it's a lens with circular concentric ridges [the red line shows cross-section] that difusses the light in [nearly] all directions so that there's no sharp edges when you project it...as in a stage production. [I didn't continue the lines all the way to the center] However, if you're on the backside of a Fresnel, it collects light like peripheral vision and you can see nearly 180 deg. left and right. A while back, plastic sheet Fresnels were popular to hang in windows to gather sunlight.