The report describes the design, development, and testing of an in situ fine particle measuring device--the Fine Particle Stack Spectrometer System (FPSSS). It is a laser-fed optical system with detection by near-forward light scattering. Sample volume is established by a high-resolution optical system that views particle images in a dark field through a masked beam splitter. The FPSSS covers an 0.5 to 11.0 micrometer size range with 60-channel resolution. Absolute theoretical accuracy is + or - 20% of size for completely unknown refractive index. The FPSSS is designed to operate continuously at in-stack temperatures up to 250C at flow velocities up to 30 m/sec. It has been laboratory characterized and field tested on coal-fired power plants at both the inlets and outlets of control devices. Its performance indicates good agreement with impactors and excellent agreement with opacity meters in computed mass loading and optical opacity. Its size resolution is greater than other currently known techniques. Its eventual use will be directed at characterizing particulate emissions of stacks or other stationary sources and qualitatively evaluating the performance and collection efficiencies of particulate control devices now in operation.

"May 1984." "EPA-600/2-84-096" Microform.