An object is at a distance of 20 m from a convex lens of focal length 0.3 m. The lens forms an image of the object. If the object moves away from the lens at a speed of 5 m/s, the speed direction of the image will be:
(Note that f, but not the f-number is the focal length!) This implies a numerical aperture of sin(1/4)≈ 0.247, but the f-number specification is more common for photographic objectives. Biconvex, Plano-convex, Biconcave, Plano-Concave and Meniscus Lenses The focusing lenses shown in...
When a voltage is applied across the LC layer, a centro-symmetrical gradient distribution of refractive index within the LC layer occurs. The difference in indexes of the LC layer and patterned substrate causes light to focus. By controlling the applied voltage, the focal length of the lens ...