Laser Cleaning Head Scanning for Shorter Ocular Hazard Distance
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Solution Overview
Problem
Conventional laser cleaning systems require long working distances and physical enclosures to ensure safety, limiting their use in public spaces and increasing costs due to the need for laser safety goggles and enclosures, as they often have high Nominal Ocular Hazard Distances (NOHD) and require high power and pulse energies for effective cleaning.
Innovation Solution
A laser cleaning apparatus with a scanning mechanism that increases the effective divergence of the laser beam, allowing safe operation in public spaces without enclosures, by monitoring and adjusting the divergence to maintain a safe working distance and using proximity sensing to prevent unauthorized access, enabling eye-safe operation with high-power lasers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high power and pulse energy lasers are used to clean large areas effectively, then cleaning productivity is improved, but the Nominal Ocular Hazard Distance increases making the system unsafe for public spaces
Solution Approach 1:
The laser beam is divided into multiple pulses that scan across the surface in a systematic pattern. Instead of using a single high-power continuous beam, the system segments the energy delivery into discrete pulses distributed across the treatment area, reducing the hazard distance while maintaining cleaning effectiveness.
Solution Approach 2:
The laser operates in a pulsed manner with periodic scanning motion, delivering energy in controlled intervals rather than continuously. This periodic action allows the beam to move through public spaces safely while accumulating the necessary energy for effective cleaning over time.
2Object-affected harmful factors
If long working distances are used to reduce beam divergence and improve safety, then laser safety is improved, but the cleaning effectiveness reduces due to lower intensity at the surface
Solution Approach 1:
The system dynamically adjusts the scanning parameters and pulse timing to maintain optimal cleaning effectiveness at extended working distances. The scanning speed, pulse frequency, and beam parameters are dynamically controlled to compensate for the reduced intensity, ensuring effective cleaning while operating from a safer distance.
3Object-affected harmful factors
If physical enclosures and light-tight barriers are implemented to ensure laser safety, then laser safety is improved, but device complexity and operational flexibility deteriorate
Solution Approach 1:
The patent extracts the safety function from the physical enclosure concept and implements it through controlled beam parameters and scanning patterns. Instead of containing the laser with physical barriers, the system inherently ensures safety through its operational characteristics, eliminating the need for complex enclosures and light-tight barriers.
4Manufacturing precision
If tightly focused beams with small spot sizes are used for controlled cleaning, then cleaning precision is improved, but the area coverage and productivity reduce
Solution Approach 1:
The system merges multiple small focused spots into a comprehensive cleaning pattern by systematically scanning across the surface. The individual precise spots are combined through the scanning motion to achieve both high precision at each location and complete area coverage, resolving the contradiction between spot size and productivity.
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
Enables safe and efficient laser cleaning in public spaces without the need for physical barriers, reducing costs and improving operational flexibility by maintaining a safe working distance and ensuring eye safety through divergence monitoring and proximity sensing.
Implementation Method 1
the output optics is configured to focus the laser light to have a fluence at a focal plane of the output optics that is greater than an ablation threshold of a surface contaminant to be removed from a surface to be cleaned
Implementation Method 2
The scanning apparatus is configured to scan the laser light in at least one dimension across a scan region within the focal plane to cause the scanning laser light to have an effective divergence greater than the divergence of the laser light
Data Source
AI summary
Laser cleaning apparatus (100) comprising: a laser system (102) configured to output laser light having a power, a wavelength, a temporal characteristic and a divergence; a delivery cable (106) to deliver the laser light to a cleaning head; a cleaning head (110) comprising: an output aperture and output optics (116) configured to focus the laser light (104) to have a fluence at a focal plane (126) that is greater than an ablation threshold of a surface contaminant to be removed from a surface to be cleaned; scanning apparatus (118) to scan the laser light in at least one dimension across a scan region within the focal plane to cause the scanning laser light to have an effective divergence greater than the divergence of the laser light and to have a corresponding safe working distance from the output aperture determined by the effective divergence, the power, the wavelength and the temporal characteristic; and scan monitoring apparatus (120) to monitor the effective divergence of the scanning laser light and to generate an alarm signal (108) in response to determining that the effective divergence has changed.