Abstract: A dual wavelength spectrophotometer produces a relatively small, high power, high duty cycle light spot from a single relatively low power multi-chromatic light source. A Xenon arc lamp light source is focused by an ellipsoidal mirror onto a rotating partially reflective optical chopper. The chopper comprises a wheel having mirrored segments alternately separated by transparent segments. Light reflected by the mirrored segments passes through a first monochromator which produces a first monochromatic light beam. Light transmitted through the transparent segments passes through a second monochromator and emerges as a second monochromatic light beam having a wavelength different from the wavelength of said first monochromatic light beam. The first and second monochromatic light beams are recombined into a single dual wavelength light beam that is reflected through a sample to be analyzed. Reflective front surfaces are employed throughout the system in order to minimize power loss.

Abstract: A high intensity light source having high repetition rate and narrow pulse-width. The light source comprises a metal casing having coaxially mounted arcing electrodes therein which utilize the capacitance of the coaxial system to charge up to the arcing potential. One electrode is electrically connected to the end wall of the casing to provide a reflected wavefront from the end wall after an arc has been struck, such wavefront serving to extinguish the arc and thus provide a sharp pulse. The lamp may be used for such areas as photochemical and photobiological research, in place of much costlier nanosecond lasers.