  This paper presents the volumetric velocity measurement method of small
seeding tracer with diameter $5\,\mathrm{\mu m}\sim 100\,\mathrm{\mu m}$ for
volume $\geq 500\,\mathrm{cm}^3$. The size of seeding tracer is between
helium-filled soap bobbles (HFSB) and di-ethyl-hexyl-sebacic acid ester(DEHS)
droplets. The targeted measurement volume dimension equal to the volume of HFSB
seeding, which will give a higher resolution of turbulence study. The relations
between particle size, imaging and light intensity are formulated. The
estimation of the imaging result are computed for the setup design. Finally,
the methodology is demonstrated for turbulence velocity measurements in the jet
flow, in which the velocities of averaged diameter $15 \,\mathrm{\mu m}$ air
filled soap bubbles are measured in the volume of $\geq 2000\,\mathrm{cm}^3$
and $\geq 9000\,\mathrm{cm}^3$. This paper presents the volumetric velocity
measurement method of small seeding tracer with diameter $5\,\mathrm{\mu m}\sim
100\,\mathrm{\mu m}$ for volume $\geq 500\,\mathrm{cm}^3$. The size of seeding
tracer is between helium-filled soap bobbles (HFSB) and di-ethyl-hexyl-sebacic
acid ester(DEHS) droplets. The targeted measurement volume dimension equal to
the volume of HFSB seeding, which will give a higher resolution of turbulence
study. The relations between particle size, imaging and light intensity are
formulated. The estimation of the imaging result are computed for the setup
design. Finally, the methodology is demonstrated for turbulence velocity
measurements in the jet flow, in which the velocities of averaged diameter $15
\,\mathrm{\mu m}$ air filled soap bubbles are measured in the volume of $\geq
2000\,\mathrm{cm}^3$ and $\geq 9000\,\mathrm{cm}^3$.
