Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Nanoparticle size determination using optical microscopes



Ravikiran Attota, Richard J. Kasica, Premsagar P. Kavuri, Hyeong G. Kang, Lei Chen


We present a simple method for size determination of nanoparticles using conventional optical microscopes. The method, called through-focus scanning optical microscopy (TSOM), makes use of the four-dimensional optical information collected at different focus positions. Low partial coherence illumination combined with analysis of through-focus optical content enables nanoparticle size determination with nanometer scale sensitivity. We experimentally demonstrate this using fabricated Si nanodots and spherical gold nanoparticles. The method is economical, as no hardware modifications to conventional optical microscopes are needed. In addition, the method also has high throughput and potential for soft nanoparticle size determination without distortion.
Applied Physics Letters


nanoparticles, TSOM, size, optical microscope, nanotechnology


Attota, R. , Kasica, R. , Kavuri, P. , Kang, H. and Chen, L. (2014), Nanoparticle size determination using optical microscopes, Applied Physics Letters, [online], (Accessed April 18, 2024)
Created October 27, 2014, Updated November 10, 2018