Yk. Kim et al., OPTICAL HETERODYNE INTERFEROMETRY TECHNIQUE FOR SOLUTION CRYSTAL-GROWTH RATE MEASUREMENT, Optical engineering, 37(2), 1998, pp. 616-621
A noncontact optical heterodyne technique was implemented for in situ
measurement of crystal growth rate from solutions. A two-frequency Zee
man laser with a total output power of 1 mW (each polarized component
is 0.5 mW) was used at 633 nm and is composed of two frequencies v(1)
and v(2) that are collinear but polarized orthogonally to each other a
nd separated by precisely 250 kHz. The sensitivity of the system was f
ound to be 0.77 nm. This Value is larger than the theoretical resoluti
on limit of 0.065 nm because of the noise associated with the vibratio
ns. The critical factors of the heterodyne technique far the monitorin
g of solution crystal growth have been studied. The growth rate of L-a
rginine phosphate crystal was 6.15+/-0.13 nm/s (0.53 mm/day) at the so
lution temperature of 28.2 degrees C and seed crystal temperature of 2
6.0 degrees C. This is the first experiment in which the heterodyne te
chnique has been applied for real-time in situ measurement of crystal
growth rate. (C) 1998 Society of Photo-Optical instrumentation Enginee
rs.