Pulsed Laser Diode for Use as a Light Source for Short-Exposure, High-Frame-Rate Flow Visualization

Abstract

A pulsed laser diode (PLD) is demonstrated as a practical light source for high-speed digital schlieren and shearing-interferometric cinematogrpahy. Frame rates of greater than 300k fps with exposure times on the order of 10 ns have been achieved with an inexpensive and user-friendly setup. The light source has primarily been used in our laboratory to study nonsteady phenomena in high-speed gas flows. Examples are presented to illustrate the usefulness of the PLD as a light source with characteristics of a narrow band of wavelength, short exposure time, high frame-rate, and long pulse train duration.

Injection into Supersonic Boundary Layers

“…This allows resolution of small-scale or transient structures in the flow that cannot be observed using the continuous light source, but with the sacrifice of some spatial resolution. The pulsed diode technique in schlieren imaging is documented in [12].…”

Measurements of Instability in Supersonic Flow with Injection by Time-Resolved Flow Visualization

“…The primary diagnostic is a schlieren imaging system using a pulsed laser light source. The details and capabilities of the light source are described in Parziale et al 17 The current configuration uses a Laser Components 905D3S3J08 laser diode pulsed by a PicoLAS LDP-V 03-100 UF3 laser driver. The diode has a wavelength of 905 nm with a spectral bandwidth of 7 nm.…”

Hypervelocity Spherically-Blunted Cone Flows in Mars Entry Ground Testing

“…5. The light source for the T5 experiments was a pulsed diode light source developed by Parziale et al consisting of a Sony laser diode paired with a PicoLAS driver emitting light at 670 nm [44]. A bandpass filter and an iris placed near the focal point of the system eliminate most of the self-luminosity of the flow.…”