Abstract

We describe a device for measuring the optical quality of a lens. It employs two fiber optic bundles which are randomly intermixed and combined at one end. Narrow band, spectrally filtered light is supplied to the mixed end through the "driving" bundle. This is collimated by a long focal length achromatic doublet. Behind the lens to be tested, near its focus, is placed a reflecting surface mounted on the tip of a micrometer. The fiber optic mixed end is imaged by the collimator and test lens on the reflecting surface of the micrometer, and re-imaged at the source. Aberrations of the test lens cause light from the driving bundle to spill over into the second bundle which is attached to a radiometer. By scanning the focus of the test lens with the micrometer a graph of measured light vs. focal position for different apertures is obtained. The method is extremely sensitive to spherical and longitudinal chromatic aberration and allows modern camera lenses to be sorted easily with respect to optical quality. A raytracing model is used to relate the shape of the focal plots to the wave aberrations of the lenses studied.

© 1990 Optical Society of America