PURPOSE: To show the effect of chromatic aberration in a lens.

DESCRIPTION: Two 20cm convex lenses are available: a simple spherical lens and an achromat. Light from the point source is focused onto a slit by a cylindrical lens placed immediately in front of the source, which in turn is imaged by the 20-cm spherical lens onto a distant screen, as shown in the photograph at the left above. The screen is then rotated as shown at the right above to increase the dispersion at the image.

The image of the achromat, shown at the right below has virtually no chromatic aberration compared with that of the ordinary simple lens, seen at the left.

SUGGESTIONS:

REFERENCES: (PIRA 6A65.20)

EQUIPMENT: Bright point source with condenser lens, 20cm cylindrical lens, adjustable slit, 20cm simple lens, 20cm achromatic lens, and small screen on optical bench with extension rail.

SETUP TIME: 5 min.