Modern UV-vis spectrophotometers are quite different than when the Beckman DU was introduced in 1941. Today, dual-beam and diode-array instruments are the only choices for research. The point-by-point plotting method of the DU has largely gone to the wayside, and dispersive (prism-based) monochromators have been almost entirely superseded by gratings.

The legacy of the DU lives on in student instruments such as the Spec 20, which employs a single beam light source and phototube detector. Until recently, Spec 20 spectrometers also employed prisms and galvanometer readouts like the DU, but these have been replaced by replica diffraction gratings and digital LED readouts.

The movie below explains the workings of the two most popular types of UV-vis spectrophotometers for research use today: the dual-beam and diode-array UV-vis spectrophotometers.

In recognition of the tremendous popularity, performance, and name recognition of the original Beckman DU, Beckman Instruments, now Beckman Coulter, Inc., designates it research-grade UV instruments the DU series.