This paper reports on a new technology of simultaneous measurements of micro-fluorescent-particle position in 3D and of temperature field with high time-resolution. The technology to measure both velocity and temperature field is based on the simultaneity of micro digital holographic particle tracking velocimetry (micro-DHPTV) and laser-induced fluorescence (LIF).

We introduce the high performance computing of Digital Holographic PTV. The algorithm is used in (1) the reconstruction of particle by digital hologram for parallel computing and (2) the reconstruction of particle by digital hologram for FPGA and (3) the reconstruction of particle by digital hologram for grid computing. The numerical reconstruction from the digital hologram makes use of the Fresnel diffraction and the FFT. The visualization measurement for micro-flow are shown by these algorithms.

We have designed a PC cluster system with special purpose computer boards for visualization of fluid flow using digital holographic particle tracking velocimetry (DHPTV). In this board, there is a Field Programmable Gate Array (FPGA) chip in which is installed a pipeline for calculating the intensity of an object from a hologram by fast Fourier transform (FFT). This cluster system can create 1024 reconstructed images from a 1024×1024-grid hologram in 0.77 s. It is expected that this system will contribute to the analysis of fluid flow using DHPTV.

This paper reports on a new technology of simultaneous measurements of micro-fluorescent-particle position in 3- D and of temperature field with high time-resolution. The technology to measure both velocity and temperature field is based on the simultaneity of micro digital holographic particle tracking velocimetry (micro-DHPTV) and laser-induced fluorescence (LIF).

A calibration plate for digital holographic particle tracking velocimetry by in-line holography was developed. A quartz plate with a computer-generated hologram pattern is used to determine the distance between an image captured on the plate and a CCD camera to high accuracy. The method allows visual confirmation of the calibration. In addition, the reconstruction of the hologram of a cross marker on plates is demonstrated at distances of 35 mm and 40 mm.

We have designed a special purpose computer system for visualizing fluid flow using digital holographic particle tracking velocimetry (DHPTV). This computer contains an Field Programmble Gate Array (FPGA) chip in which a pipeline for calculating the intensity of an object from a hologram by fast Fourier transform is installed. This system can produce 100 reconstructed images from a 1024 x 1024-grid hologram in 3.3 sec. It is expected that this system will contribute to fluid flow analysis.

High time-resolution flow field measurement in two microchannels with a complex shape is performed by a micro-digital-holographic particle-tracking velocimetry (micro-DHPTV). The first microchannel has a Y junction that combines the flow of fluid from two inlets into one outlet. In this case, two laminar velocity profiles from the inlet regions merge into one laminar velocity profile. The second microchannel has a convergence region from where a fluid flows into a divergence region. At this region, two recirculation regions appear Consequently, approximately 250 velocity vectors in both cases can be obtained instantaneously. For a microchannel with the convergence region, the two recirculation regions that appear at the divergence point are captured from a three dimensional vector field, with which the axes of recircular vortices have some alignment. The reason why we can observe this phenomenon is that a three-dimensional velocity, including the depth direction, can be obtained by micro-DHPTV

A micro-digital holographic particle tracking velocimetry with high-speed system is constructed by a PC grid environment that employs Windows XP with AD-POWERs as parallel tool. Two algorithms for high-speed system are evaluated under the same PC grid environment. Both methods are based on a computer-generated hologram algorithm. One method is a division algorithm based on time development for the measurements, while the other is a division algorithm based on spatial reconstruction for the measurement. In case of the former, the performance is increased by a factor of 3.3 by using 4 PCs. The present system can compute huge hologram images and output them “on-site” at an experimental facility.

We have developed a parallel algorithm for microdigital-holographic particle-tracking velocimetry. The algorithm is used in (1) numerical reconstruction of a particle image computer using a digital hologram, and (2) searching for particles. The numerical reconstruction from the digital hologram makes use of the Fresnel diffraction equation and the FFT (fast Fourier transform), whereas the particle search algorithm looks for local maximum graduation in a reconstruction field represented by a 3D matrix. To achieve high performance computing for both calculations (reconstruction and particle search), two memory partitions are allocated to the 3D matrix. In this matrix, the reconstruction part consists of horizontally placed 2D memory partitions on the x-y plane for the FFT, whereas, the particle search part consists of vertically placed 2D memory partitions set along the z axes. Consequently, the scalability can be obtained for the proportion of processor elements, where the benchmarks are carried out for parallel computation by a SGI Altix machine.

We have designed a special purpose computer system for digital holographic particle tracking velocimetry (DHPTV). We present the pipeline for calculating the intensity of an object from a hologram by fast Fourier transform in an FPGA chip. This system uses four FPGA chips and can make 100 reconstructed images from a 256x256-grid hologram in 266 msec. It is expected that this system will improve the efficiency of analysis in DHPTV.

High time-resolution flow field measurements in a micro-flow is performed 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. Particle positions in a three-dimensional field can be reconstructed by a computer-generated hologram. The error of reconstruction in the z-directions is evaluated by traverse of particles on a glass plate. A velocity error in z-direction is obtained by uncertainty analysis. The time evolution of a three-dimensional water flow in a semicircular micro-channel of 101.9 [μm] width and 32.5[μm] depth and in a circular micro-pipe of 92 [μm] inner diameter are obtained successfully using this micro-DHPTV system. The volume of the system is defined by 409.6 [μm] ×92 [μm] ×92 [μm], and is irradiated by a laser beam with a resolution time of 100 [μs], and a repetition rate of 1 [kHz]. Consequently, approximately 100 instantaneous velocity vectors on each 1 000 frames for 1 [s] in the micro-channel can be obtained.

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 mu m x 92 mu m x 92 mu m. It is illuminated by a laser beam with a pulse length of 58 ns, a resolution time of 100 mu s 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 mu m 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.

A micro digital-holographic particle-tracking velocimetry (micro-DHPTV) method for high time-resolution flow field measurement in a micro-channel is developed. The system consists of an objective lens, a high-speed camera and a single high-frequency double pulsed laser. Particle positions in a three-dimensional field can be reconstructed by a computer-generated hologram. The time evolution of a three-dimensional water flow in a semicircular micro-channel of 100μm width and 40μm depth is obtained successfully using this micro-DHPTV system. The three-dimensional measurement volume of the system is 410μm×100μm×40μm and is irradiated by one laser beam with the time resolution of 100μsec and a reputation rate of 1kHz. Consequently, 130 velocity vectors in the semicircular micro-channel can be obtained instantaneously. A significant aspect of this method is that even though both the laser and camera are located in line and perpendicular to the flow direction, velocity vectors can be obtained by reconstructing the particle positions via the computer hologram and the semicircular cross section shape of the micro-channel can be resolved.

A micro digital-holographic particle-tracking velocimetry (micro-DHPTV) method for high time-resolution flow field measurement in a micro-channel is developed. The system consists of an objective lens, a high-speed camera and a single high-frequency double pulsed laser. Particle positions in a three-dimensional field can be reconstructed by a computer-generated hologram. The time evolution of a three-dimensional water flow in a semicircular micro-channel of 100-μm width and 40-μm depth is obtained successfully using this micro-DHPTV system. The three-dimensional measurement volume of the system is 410 × 100 × 40 μm3 and is irradiated by one laser beam with the time resolution of 100 μs and a reputation rate of 1 kHz. Consequently, 130 velocity vectors in the semicircular micro-channel can be obtained instantaneously. A significant aspect of this method is that even though both the laser and camera are located in line and perpendicular to the flow direction, velocity vectors can be obtained by reconstructing the particle positions via the computer hologram and the semicircular cross section shape of the micro-channel can be resolved.

Digital holographic particle tracking velocimetry (PTV) is developed by single high-speed camera and single double pulsed laser with high frequency pulses. This system can directly capture 1000 hologram fringe images for 1 second through a camera computer memory. The 3-D particle location is made of the reconstruction by using a computer hologram algorithm in a personal computer. This system can successfully be applied to instantaneous 3-D velocity measurement in the water flow with a square obstacle, and can obtain an average of 300 instantaneous velocity vectors.

A three-dimensional particle tracking velocimeter for turbulent air flow measurement was developed. As a tracer particle, spherical plastic capsules and He-filled bubbles were tested. The plastic capsule's traceability was anticipated to be insufficient for high-frequency components of turbulence because its density was thirty times larger than that of air, its diameter was small enough compared with the turbulent microscale, and the image was clear enough to track. On the other hand, the bubble, which was neutrally buoyant, had a relatively large diameter and its image had two peaks in brightness. The previous 3-D PTV system was modified so that two successive instantaneous particle images could be recorded on two successive TV fields with an arbitrary time interval. In order to evaluate the present technique, a fully developed turbulent air flow in a square-cross-section duct was measured. Cross-stream distributions of the mean velocities and of the full Reynolds stress tensor components were obtained and some of them were compared with a separate hot-wire measurement. The agreement was generally good for both tracers. However, part of the plastic particles adhered to the bottom wall of the duct and caused serious errors in the measurement.

The three-dimensional particle tracking velocimeter (3-D PTV) is a powerful measurement technique which provides information on all three components of instantaneous velocity in a large space. However, there still remain several problems in the 3-D PTV; in particular, its application to air flow measurement is an urgent requirement in practical use. In this study, the 3-D PTV was applied to the measurement of a turbulent air flow in a duct of square cross-section. As a result, detailed distributions of the mean and fluctuating velocities were measured.

Digital holographic particle tracking velocimetry (PTV) is developed by single high-speed camera and single double pulsed laser with high frequency pulses. This system can directly capture 1000 hologram fringe images for 1 second through a camera computer memory. The 3-D particle location is made of the reconstruction by using a computer hologram algorithm in PC cluster. This system can successfully be applied to instantaneous 3-D velocity measurement in the water flow with a square or a circular cylinder obstacle, and can obtain an average of 170 instantaneous velocity vectors.