The Holographic Multi-wavelength Imaging Extinctometer (HoloMIE) is an instument that resolves the size and shape of single free-flowing aerosol particles. Also measured is the extinction cross section of the particle at two visible wavelengths. The measurement principle involves holography within a novel optical design and can image both spherical and nonspherical aerosol particles in the so-called coarse-mode size range, i.e., larger than several micrometers in size.