Laser Decontamination Device with Z-Axis Scanner for Uniform Power Density
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Solution Overview
Problem
Conventional laser decontamination methods face challenges in achieving high power density for deep-seated radioisotope removal, suffer from uneven irradiation, thermal diffusion, and recontamination, and are costly and environmentally unfriendly due to mechanical and chemical methods.
Innovation Solution
A laser decontamination device employing a CW laser with a Z axis scanner and XY axis scanner, using a single mode fiber laser for high power density focusing without compound lenses, combined with a gas jet-spraying system for particle removal and a remote-controlled robot for safe operation, allowing precise three-dimensional scanning and high-efficiency decontamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If pulse laser beams are rendered into parallel light to enhance power density, then power density is improved, but uneven irradiation occurs causing the same spot to be irradiated several times
Solution Approach 1:
The patent employs periodic pulsed laser irradiation with controlled duty cycles to achieve uniform energy distribution. By timing the pulses to match the scanning motion, the system delivers energy in periodic bursts that accumulate uniformly across the treatment area, preventing both under- and over-irradiation of any single spot while maintaining high peak power density for effective decontamination.
2Area of stationary object
If the irradiation area of one pulse is enlarged to cover more area, then irradiation area is improved, but power density is lowered
Solution Approach 1:
The patent segments the irradiation process into multiple overlapping pulse zones that collectively cover the entire decontamination area. Each pulse maintains high power density in its local spot, but the segmented pattern of multiple pulses ensures complete area coverage. The segmentation allows the system to achieve both high power density (in each spot) and large effective treatment area (through cumulative coverage).
Solution Approach 2:
The patent transitions from single-dimension spot treatment to two-dimensional area treatment by implementing a scanning mechanism that moves the high-power-density laser spot across the surface. This dimensional change allows the system to maintain high power density at the focal point while covering large areas through systematic scanning motion, effectively resolving the contradiction between concentrated power and broad coverage.
3Reliability
If mechanical methods are used to remove attached RIs, then decontamination is achieved, but recontamination occurs and grinding devices are secondarily contaminated
Solution Approach 1:
The patent replaces mechanical decontamination methods (grinding, sandblasting) with laser-based thermal processing. The laser energy directly vaporizes and removes radioactive contaminants through ablation without physical contact, eliminating the source of secondary contamination that plagues mechanical methods. This substitution maintains effective decontamination while preventing both recontamination and secondary contamination of equipment.
4Power
If high-output pulsed laser beams are employed to achieve high power density, then power density is improved, but thermal diffusion and reattachment of RIs are aggravated
Solution Approach 1:
The patent uses periodic pulsed laser irradiation with carefully controlled pulse durations and intervals. The periodic nature allows brief high-power bursts for effective decontamination followed by cooling intervals that prevent excessive heat accumulation. This temporal modulation of power delivery achieves high instantaneous power density for contaminant removal while the periodic cooling periods minimize thermal diffusion and prevent radioactive material reattachment.
Solution Approach 2:
The patent implements continuous scanning motion combined with continuous pulsed laser irradiation, ensuring that the high-power-density treatment is continuously applied across the entire decontamination area without interruption. This continuous action, when properly synchronized with scanning speed, maintains optimal power density at each location long enough for effective contaminant removal but limits total heat exposure time, thereby reducing thermal diffusion and reattachment risks.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device achieves significantly higher power density for complete removal of deep-seated radioisotopes without thermal diffusion, reduces recontamination, and lowers operational and environmental costs by enhancing scanning velocity and precision while minimizing equipment exposure and waste production.
Implementation Method 1
the contaminants deriving from RIs, which are black and others in color and higher in photoabsorption, are vaporized for removal without doing damage on the base metal
Implementation Method 2
irradiating substantially parallel light pulse laser beams of lower average power output onto the surface of the objects contaminated by the RIs
Implementation Method 3
a gas jet-spraying system for particle removal
Data Source
Figure 1
Figure 2~3
Figure 4(a)~5(b)
AI summary
To provide a laser decontamination device allowing sufficiently a high power density to remove inclusively the RIs advanced deeply into the contaminated article to be secured; doing without uneven irradiation density even when there are irregularities on the surface of the contaminated article; dispensing with the thermally induced diffusion and recontamination of the RIs during the laser machining; further being excellent in cost-saving and eco-friendly aspects as well as operational efficiency. The laser decontamination device comprises: a laser oscillator (1); a scanning device (2) provided with an XY axis scanner (21) and a Z axis scanner (22) to condense the laser beam (L1) emitted from the laser oscillator (1) onto the surface of the contaminated article (T) without the intervention of any compound lens such as an f θ lens so as to optically scan the surface; and a surface shape measuring device (3) to measure the surface shape of the contaminated article (T), the Z axis scanner (22) being provided with a focus position controlling section (22b) to automatically adjust a focus position in accordance with an irradiation position such that a focus of the laser beam (L1) comes on the surface of the contaminated article (T) based on a shape data obtained at the surface shape measuring device 3.