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US 5,327,217 AGranted
Apparatus for measuring particulate size without contacting the particulate
AssigneeKanai School Incorporated
InventorsKenzo Kanai, Hiroshi Ito, Norikane Kanai
Life of this patent
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Abstract
An apparatus is described for measuring the size of a particulate, without contacting the particulate, and therefore without extra forces on the particulate. Stripped gaps of interference fringes are measured behind the particulate when a monochromatic beam is radiated on the particulate.
Claims3
An apparatus for measuring particulate size without contacting the particulate, comprising:
- (a) means for radiating a monochromatic laser beam on a path;
- (b) spatial filter means, positioned in the path between the means for radiating and the particulate, for diverging the monochromatic beam from said radiating means and for forming behind the particulate a clear boundary diffraction interference fringe accurately inversely proportionate to the particulate size, by diffracting at a boundary around said particulate, when said particulate in a measuring position is radiated by said diverging monochromatic beam;
- and
- (c) means for measuring the gap .DELTA.x of the boundary diffraction interference fringe and calculating the size of the particulate based on the formula D=.lambda.Z/.DELTA.x, where D is the size of the particulate, .lambda. is the wavelength of the monochromatic beam, and Z is the distance between the particulate and said boundary diffraction interference fringe.
1 more element
Dependencies are inferred from the claim text.