A new holographic measurement of frequency sweeping of the output from a Q-switched ruby laser

The power dependent frequency sweep of a Q-switched ruby laser

The frequency chirp of a Q-switched ruby laser is investigated with two interference experiments: holography of a rotating object and measurement of time coherence. Nonlinearity of the frequency chirp markedly affects both interference experiments for large time differences between the two beams, which enable us to determine the nonlinear frequency chirp, that is, chirp rate and time. A hyperbolic tangent function provides a better approximation of the frequency chirp than the linear function generally used. In this experiment the chirp time was 1.0–1.5 times as long as the half-intensity width of the pulse.

Measurement of nonlinear frequency chirp of Q-switched ruby laser.

A holographic measurement of the pulse width of a Q-switched ruby laser

Holographic investigation of the temporal-coherence of the output of a Q-switched ruby laser

We have assembled a single-transverse-mode, single-longitudinal-mode ruby laser with a pulse length of ~6–12 ns (intensity half-height full width). Pulsed holograms have been made by use of this laser. The laser carrier-frequency shift (or chirp) has been measured and is found to be the limiting factor on the depth of field of the hologram. In order to demonstrate this, we present a quantitative measurement of hologram quality.

Henry H. Chau

Papers

Effect of Carrier-Frequency Shift on Short-Pulse Holography*