1] Pulsed laser interferometry in the ultracentrifuge

Abstract

This chapter presents two experimental arrangements to describe the role of pulsed laser light in the ultracentrifuge: one arrangement employs a pulsed argon ion laser of moderately high intensity, while the other modulates a low power helium–neon gas laser either externally with a Pockel cell or by means of internal switching. Both arrangements make possible the illumination of (tangentially) selected regions of the rotor and cells. The Pockel cell modulation system makes possible finer control of the region to be illuminated because of its shorter pulse length, down to 0.8 μsec compared to the ∼6 μsec for the unmodified pulsed argon ion laser. The argon ion laser emits significantly higher light intensity than the He–Ne lasers used and, in addition, can provide a number of laser lines in the green and blue region of the spectrum. The pulsed argon ion laser system is also described in the chapter. Studies show that the pulsed argon ion laser is promising as a light source for real-time data acquisition with the Rayleigh optics.