The Virometer instrument completes a measurement on live or dead virus in approximately fifteen minutes at concentrations as low as 107 particles per milliliter and works with sample volumes of one microliter. Early work has shown results with virus particles in the 300 R to 1500 R size range, and at concentrations of 108 to 1012 particles per milliliter. In addition to nucleic acid type and quantity, the "Virometer" also determines single or double-strandedness of DNA. The instrument includes an Argon laser, modified light micro-scope optics, and special light detection system utilizing attenuated total reflection fluorescence, and light-scatter measurement. A special mixture of RNA and DNA-revealing fluorescent dyes is added to a sample preparation. After staining takes place, the sample preparation is observed through an optical aperture smaller than a single light wavelength yielding size information via Brownian motion, even in the presence of high background found in typical biological fluids. Additional processing determines titer and individual particle nucleic acid mass. Autocorrelation and Fourier transformation are used in specialized electronics to allow essentially real-time data reduction.
"Real Time Measurement And Observation Of Viruses In Biological Fluids", Proc. SPIE 0104, Multidisciplinary Microscopy, (26 August 1977); doi: 10.1117/12.955411; https://doi.org/10.1117/12.955411