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Browse Prior Art Database

Prevention of Redeposition of Pulsed-Laser Removed Particulates

IP.com Disclosure Number: IPCOM000112021D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Dawson, BL: AUTHOR [+5]

Abstract

Disclosed is an apparatus and process to clean off particulates of sizes on the order of microns or sub-microns from a surface without the danger of redepositon of these removed particulates back onto the surface.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 67% of the total text.

Prevention of Redeposition of Pulsed-Laser Removed Particulates

      Disclosed is an apparatus and process to clean off particulates
of sizes on the order of microns or sub-microns from a surface
without the danger of redepositon of these removed particulates back
onto the surface.

      It has been observed that pulsed laser irradiation of a solid
surface (either as-is or coated with a thin liquid-layer of thickness
on the order of a micron) can cause the ejection of particulates from
the surface.  When appropriate laser fluence is used, the particulate
ejection effect has the following features:  (1) The particulates are
ejected nearly perpendicular to the surface, within an opening angle
of about 5 degrees from the normal; (2) The ejected particulates have
high initial speed (usually supersonic), but air damping causes these
particulates to decelerate in the ambient atmospheric conditions and
become stationary at a distance of the order of 1 cm from the
surface.  Since the initial normal velocities of the ejected
particulates are supersonic, such high velocities enable them to
cross the flow-lines of a laminar gas flow.  When completely
decelerated, the particulates thus come to rest in a central part of
the laminar flow, which then can efficiently carry the particulates
away from the surface to be laser-cleaned.  Since the overall amount
of material that is ejected into the laminar gas flow is extremely
small, little disturbance of the laminar flow would...