The capabilities and limitations of rainbow refractometry, specifically the minimum measurable droplet size and the errors in the refractive index (temperature), have been studied. We evaluate what we believe is a new method of indirectly applying the Lorenz-Mie theory to rainbow refractometry. The results show that this new method reduces the errors and eliminates the biases that may occur if the Airy theory is used. A more precise method to filter the high-frequency oscillations associated with the measurement signals was developed. Finally, it was discovered that the errors associated with rainbow refractometry are such that a single droplet measurement is unreliable. A mean refractive index should be determined on the basis of multiple droplet measurements.
© 2002 Optical Society of America
Original Manuscript: June 1, 2001
Revised Manuscript: October 29, 2001
Published: April 1, 2002
James Hom and Norman Chigier, "Rainbow refractometry: simultaneous measurement of temperature, refractive index, and size of droplets," Appl. Opt. 41, 1899-1907 (2002)