A new inverted laser trapping microscope, combined with a linear diode array, has been developed to measure light scattering from a single cell over a large (up to approximately equals 45 degree(s)) angular range in real time. Diffraction profiles from 5 and 10 micrometers diameter polystyrene dielectric microspheres are in qualitative agreement with Lorenz-Mie calculations in terms of the separation and number of side-lobe features. Diffraction profiles from red blood cells (RBC), Chinese Hamster Ovary (CHO) cells, and liposomes exhibit features that can ultimately be correlated to their size and shape. Results obtained with this instrument can be used to determine the optical properties of the trapped cell, the location of the cell in the optical trap with respect to the laser focal point, and the forces acting on the cell.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.