optics.gif (6954 bytes)

SPHERICAL ABERRATION








EQUIPMENT
    redball.gif (326 bytes) Lens
    redball.gif (326 bytes) Diaphragm
    redball.gif (326 bytes) Aberration Device
    redball.gif (326 bytes) 6 V Lamp
  


NARRATIVE
             Spherical aberration due to inaccurate focusing through the outer circumference of a lens can be eliminated by only allowing light to pass through a small area of the center of the lense.

            Project an image through the converging lens onto the screen. The image is blurred. Place the plate with five holes over the lens. Now five separate images are seen.

            Close the four outside holes, and the central image becomes sharp, and the others are blocked. The plate may be replaced by an adjustable diaphragm. Open the diaphragm and the image is blurred. Close it and the image becomes sharp.