Measurements of 3D flow in a micro-pipe via micro digital holographic particle tracking velocimetry

Abstract

This paper details high time-resolution flow field measurements in a micro-pipe made by a micro digital holographic particle tracking velocimetry (micro-DHPTV) method. The system consists of an objective lens, a high-speed camera and a single high-frequency double pulsed laser. The volume of the system is 409.6 µm × 92 µm × 92 µm. It is illuminated by a laser beam with a pulse length of 58 ns, a resolution time of 100 µs and a repetition rate of 1 kHz. 104 velocity vectors could be obtained instantaneously in the micro-pipe. Particle positions in the three-dimensional field are reconstructed by a computer-generated hologram. The time evolution of a three-dimensional water flow in a micro-pipe of 92 µm inner diameter is obtained successfully using the micro-DHPTV system. The error of reconstruction in the z-direction is evaluated by analysing the traverse of particles on a glass plate and obtaining the velocity error in the z-direction by uncertainty analysis.

Particle imaging techniques for volumetric three-component (3D3C) velocity measurements in microfluidics

“…They measured the flow field in a circular pipe over a depth of 40 lm with an out-of-plane resolution of 0.2 lm. Later, they were able to increase the measurement depth to 70 lm, close to their original objective of 100 lm (Satake et al 2006). They used a high-speed CMOS camera with a relatively large pixel size of 16 lm and 40x magnification.…”

Development of an Off-Axis Digital Holographic Microscope for Large Scale Measurement in Fluid Mechanics

“…The remarkable aspect of digital reconstruction is the topic of the present study. Digital holographic microscopy has proved to be useful in solid and fluid measurements since it allows digital processing of the wavefronts [5,6]. In comparison to HPIV, the measurement volume with digital holographic microscopy is significantly less due to inferior pixel resolution of the imaging sensor.…”

Astigmatism compensation in digital holographic microscopy using complex-amplitude correlation

“…To overcome these limitations, Satake et al [2] fabricated polymer micro-channels with a refractive index comparable to that of water, and immersed in water. Another techniques include use of corrective optics with phase conjugation [3] and ray tracing [4] to compensate for aberration in microscopic objects introduced by thick cylindrical windows.…”