Radiant energy – Luminophor irradiation – With ultraviolet source
Reexamination Certificate
1999-10-05
2001-08-14
Epps, Georgia (Department: 2873)
Radiant energy
Luminophor irradiation
With ultraviolet source
C250S459100
Reexamination Certificate
active
06274874
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process and apparatus for monitoring the cleaning of a surface by laser irradiation.
2. Discussion of Prior Art
In many manufacturing processes such as for aircraft and automobiles components have to be cleaned prior to joining or coating. Conventionally this task is performed by wet cleaning using either water jets or solvents. In both cases the liquid residue remaining after cleaning has to be disposed of. Due to the impact of the solvents or the residue containing liquids upon the environment and the costs associated with the disposal of these chemicals, alternative cleaning techniques are desirable which do not involve the use and disposal of environmentally hazardous chemicals or residues.
It has been proposed to use a cleaning process which involves the irradiation of a surface by laser to remove contaminants such as solvents or epoxy particles. However it is also advisable to monitor the effectiveness of such laser cleaning processes and techniques have been proposed for doing this by plasma or ion emission analysis. One of the disadvantages of such monitoring techniques is that they can only monitor the very area the laser pulse is cleaning and no analysis can be performed on the area that is to be cleaned or the area that has been cleaned. Additionally the analysis process is time consuming and relatively expensive to carry out.
There is thus a need for a generally improved and simplified process of monitoring the cleaning of a surface by laser irradiation which can be used more effectively across the whole area of the surface to be cleaned.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a process for monitoring the cleaning of a surface by laser irradiation in which the surface to be cleaned, being cleaned, or having been cleaned is illuminated by ultra-violet irradiation sufficient to excite into fluorescence contaminants on the surface which fluoresce under ultra-violet irradiation.
Preferably the intensity of fluorescence or the rate of decay of fluorescence is measured to indicate the area and thickness of contaminant on the surface.
Conveniently the intensity or rate of decay measured is utilised controllably to vary operating parameters of the cleaning laser.
Advantageously the ultra-violet irradiation is provided by an ultra-violet lamp.
Alternatively the ultra-violet irradiation is provided by an ultra-violet laser.
According to a further aspect of the present invention there is provided apparatus for cleaning a surface by laser irradiation, including a source of laser irradiation and means for irradiating the surface with ultra-violet radiation before, during or after cleaning, to monitor the area and extent of contaminant on the surface.
Preferably the apparatus includes a sensor for detecting the intensity or rate of decay and area of fluorescence excited on the surface by the ultra-violet irradiation.
Conveniently the apparatus includes means for controllably varying operating parameters of the cleaning laser in response to the detected intensity or rate of decay and area of fluorescence.
Advantageously the source of laser irradiation is an ultra-violet cleaning laser which additionally provides the means for irradiating the surface with the ultra-violet monitoring radiation.
Preferably the source of laser irradiation is a non ultra-violet or an ultra-violet cleaning laser and wherein the means for irradiating the surface with ultra-violet monitoring radiation is an ultra-violet lamp.
REFERENCES:
patent: 4641650 (1987-02-01), Mok
patent: 5256880 (1993-10-01), Loree et al.
patent: 5399867 (1995-03-01), Kohno
patent: 5643472 (1997-07-01), Engelsberg et al.
patent: 5669979 (1997-09-01), Elliott et al.
patent: 4 216 189 (1993-11-01), None
patent: 0 709 145 (1996-05-01), None
patent: WO 88/08279 (1988-11-01), None
patent: WO 95/07152 (1995-03-01), None
Measures et al, “Analyzing Fluorescence Decay” Laser Focus, (Nov. 1974) p. 49.
BAE Systems plc
Epps Georgia
Hanig Richard
Nixon & Vanderhye P.C.
LandOfFree
Process and apparatus for monitoring surface laser cleaning does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process and apparatus for monitoring surface laser cleaning, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process and apparatus for monitoring surface laser cleaning will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2438555