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HOLOGRAM TECHNIQUES FOR PARTICLE‐SIZE ANALYSIS
Author(s) -
Zinky William R.
Publication year - 1969
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.1969.tb56196.x
Subject(s) - holography , photography , optics , depth of field , particle (ecology) , laser , particle size , computer science , computer graphics (images) , physics , geology , art , paleontology , oceanography , visual arts
S ummary Fraunhofer hologram camera systems have been applied to a number of applications for particle‐size analysis. Reconstructed holograms provide high‐quality images with three orders of magnitude greater depth of field than that provided by a microscope. Instantaneous recording of dynamic dispersions with freedom from isokinetric sampling losses is one of the chief attractions of the method. A permanent record of the particle distribution that can easily be recalled is produced. The typical laser pulse length of 20 nanoseconds allows particles to be moving at high velocities; the maximum particle velocity criterion is that the particle shall move less than 1/10 diameter during the exposure time. A hologram has extremely high information content; in fact, it contains the size, shape and position in three‐dimensional space of a large number of objects. The price that must be paid for recording this large amount of information is that lasers and precision optical systems must be used in a two‐step process to record and reconstruct the holograms. Hologram photography has, however, all the advantages of direct photography; it gives shape information and shows the minute detail of the microcosm. Scientists trained to utilize this new hologram technique can further their work in fine‐particle analysis.