Design of a photographic ultramicroscope for observing fine particles in the air
Studies on design and application of a photographic ultramicroscope.I
1963 Volume 12 Issue 11 Pages 1017-1027
Details
1963 Volume 12 Issue 11 Pages 1017-1027
Various modifications of a photographic ultramicroscope were designed, constructed and tested. The most satisfactory design involved a xenon arc lamp and used a high-sensitivity film (such as SSS) at an exposure time of 1/4 to 1/2 second. The use of an objective with magnification factor of 5 to 10 and of an eye piece with magnification factor of 15 were found sufficient. The focus length was 20 μ. The maximum depth of space, where all of recognizable aerosol particles were contained, was called the effective counting depth.
The depth of this ultramicroscope was estimated as 1120 μ by measurement using an objectives of magnification 10 and an eye piece of magnification 15. Then the volume of cube space in which the visible particles are present estimated as 3 × 10-4 (cc). The saturation type temperature raising within the cell during illumination was found by measuring with a thermister. A method of measuring particle size from the measuremenent of variation of particle concentration with time at a given horizontal level within a cell and a method of measuring the dispersion of aerosol particles within a cell upon injection were both proposed.
The design was constructed so as to be able to measure the effect of scattering angle of beam illuminating particles upon measurement of size distribution of tobacco aerosol, but no remarkable effect was observed.
