Development of Particle Measurement Module by Using Phase Retrieval Holography

Abstract

We have developed a phase retrieval holography module for microparticle measurement. The system that this module has comprises two cameras connected to a single-board computer (SBC) with a graphics processing unit (GPU), a diode-pumped solid-state green laser, and a beam splitter. Furthermore, the GPU provides real-time reconstruction. The system can record the shapes and positions of particles falling in a static flow in a three-dimensional volume as two holograms generating an interference pattern. Phase retrieval holography with two holograms solves the twin image problem that arises due to the lack of phase information. We also present the requirement of this module for experimentally recording and numerically reconstructing holograms of particles. Finally, we conclude that holographic measurement, limited to use in a laboratory, can be used for in-line/ on-line measurement of powder production processes.

Graphical Abstract

Optical setup for particle size measurement using phase retrieval holography system with a GPUequipped SBC: (a) laser; (b) objective lens; (c) collimator lens; (d) ND filter; (e) observation box; (f) beam splitter; (e) telecentric lens; (h1) CMOS camera 1; (h2) CMOS camera 2; (i) NVIDIA Jetson Nano as GPU-equipped SBC.