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Author Topic: Safety Enhanced Handheld Laser Cutting Tools  (Read 3391 times)

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Offline Photonic Bladesmith

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Safety Enhanced Handheld Laser Cutting Tools
« on: August 07, 2016, 04:50:32 AM »
Safety Enhanced Handheld Laser Cutting Tools



 


 


 


While this post is not about anything related to Star Wars or Star Wars props, multiple people who have seen this series of prototype laser cutting tools that I constructed have mentioned the cutting tool's coincidental resemblance to Star Wars Lightsabers.

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Background - "Laser Flashlight" Configured Cutting Tool Hazards

The recent availability of high power laser diodes and compact high power density batteries has made possible the construction of hand held laser flashlight configured "burning lasers."  There have been speculations that the continual increase in the output power of these hand held burning lasers would ultimately make possible a new class of portable hand held industrial cutting tools.

Accident reports with current technology 1 to 5 watt class hand held "laser flashlights" have subsequently started to be posted on experimenters forums implying that laser flashlight configured laser cutting tools may be unacceptably hazardous:

- Virtually all current conventional hand held metal and woodworking cutting tools are used within arm's length of the worker and pose minimal hazard to co-workers outside of this arm's length work envelope.

Laser flashlight configured cutting tools can cut, ignite flammable materials and cause permanent eye damage far past the arm's length distance that one would be using them to cut and shape materials causing great potential danger to co-workers and bystanders.

- Laser safety glasses that block the laser beam wavelength, which must be worn by the operator to guard against eye damage, can actually increase the chance of other types of accidents by making the location of the hazardous cutting beam and beam reflections invisible to the operator.

- The fact that unlike drills and power saws, laser flashlight configured burning lasers are silent have led to accidents due to these burning lasers being unknowingly switched on, with the user and those around him being unaware of the hazard until the beam started to cause tissue burns, ignite objects or cause eye damage.

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Safety Enhanced Laser Cutter Design


To address these laser cutter hazards, a safety enhanced hand held laser cutter has been designed.

A solid state blue laser generates the cutting beam, which is spatially terminated by having it laterally illuminate a high melting temperature beam stop rod coated with fluorescent material.

 



The grazing angle laser illuminated edge of the beam stop rod produces a brightly illuminated, spatially terminated laser cutting zone.

The fluorescent coating on the beam stop rod wavelength shifts the blue laser light into non-spatially coherent light of a color that can be safely viewed with safety glasses that simultaneously blocks the wavelengths of the original highly collimated laser light.  This allows the worker to safely observe the cutting beam state of operation, location and alignment.  The beam stop rod can be designed to automatically extend and retract to make the cutting tool more compact when not in use.

The hazards associated with silent accidental actuation is easily addressed by adding aural state of operation sound feedback.  An obvious set of sound cues:
- The universal danger sound for a powered up electrical device is a 60 cycle hum.
- This 60 cycle hum can be Doppler shifted when the cutter is put into motion as a warning to the operator and co-workers.
- A short loud white noise burst, loud enough to be heard as an actuation warning throughout the work area, can signal the switching on or off of the laser cutting hand tool.

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Fixed Beam Stop Rod Prototype

 


A fixed position, fluorescent coated rod, low power laser cutter prototype constructed with a low cost (<$50.00) blue laser diode was built to test the basic concept of the laterally illuminated beam stop safety enhanced laser cutter design. 

This test unit is powered by a single 18650 rechargeable lithium battery.

The battery holder is mounted on the outside of the handle so that I could tell at the glance if this laser cutter prototype is in a "battery removed" safe state.


 


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Retractable/Extendable Beam Stop Laser Cutting Tool



The next safety enhanced laser cutting tool prototype is to be improved with:

- Two 7 watt lasers illuminating opposite sides of the beam stop

- An automatically extending and retracting beam stop rod (magnetic coil actuation)


Build Log:

 


Setup for prototyping the beam stop rod magnetic actuator and Arduino control software

 


Assembling the outer housing.  Lasers not yet installed.

 


Heat sinks and alignment mounts for the lasers

 


Aligning the lasers and setting operating currents

 


Final assembly
 




 


First bench testing of the fully assembled safety enhanced laser cutter prototype

 



 


Finished safety enhanced laser cutting tool prototype

 



Videos of beam stop extension/retraction tests and light duty material cutting tests.















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Six Element Laser Array, Belt Drive Beam Stop Actuation Prototype


- Belt drive actuated long beam stop rod

- Circumferential array of six 2 watt blue lasers for omnidirectional cutting


 


Six element circumferential laser array

 


Belt drive actuation for the beam stop rod
 


Control electronics

 



Finished prototype







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Safety Enhanced Handheld Laser Cutting Tools

                            FAQ
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--Can this laser cutter design be scaled up in power?--

Definitely yes, by a very large amount in the very near future.

 


Drone aircraft battery technology has made available compact light weight batteries having multi kilowatt continuous power output capability.

 


Blue laser diodes in the 100 watt range intended for laser micromachining have already been pre-announced.  The solid state laser technology used for these blue lasers average 30% electrical energy to laser output power conversion efficiency.  Assembled into arrays, this can make for a very powerful cutting tool.

 


Tungsten beam stop rods plasma coated with fluorescent minerals can be used to make a beam stop rod having a melting temperature twice that of steel.

Heat dissipation in a hand held device is the major power limiting factor.  It will obviously not be possible in a hand held tool to run multi 100 watt class lasers continuously at full power.

One possible high peak power, low duty cycle operating mode:

Upon being switched on, the lasers will illuminate the beam stop rod at a low power level just sufficient for the operator to verify that the cutter is switched on and the lasers are properly aligned.

When the object to be cut is brought into near contact with the beam stop rod, only then will the lasers be automatically switched on to full power for the short duration required for cutting.  An additional warning sound, perhaps the sound of scorching material will be sounded when the lasers are brought to full power. 

When the cut is completed the lasers will drop back to alignment power.

Sort of a "flash-on-clash" on steroids.

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--What improvements are needed or are going to be incorporated in the next prototypes?--

Higher power laser diodes as they become available.

Experiments with different laser configurations:
-  single very high power emitter
-  single very high power emitter on a rotating gimbal
-  arrays with overlapping beams
-  circumferential arrays selectively powered

Improved beam shaping optics for improving the uniformity of the beam stop rod illumination.

Modified tip to allow linear drilling and reduce the residual forward scattered light.

The current actuation speed of the beam stop rod is almost high enough to allow operation of a multi-section telescoping beam stop using inertial ejection and retraction of the free moving segments.  Improvements in the actuation mechanism may allow significant lengthening of the beam stop rod with the same length of handle.

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--Can this laser cutter design also be used as a drill?--


There are at least two possible ways to spatially terminate the laser beam used in this cutter so that this cutting tool can be as a drill.

One method is to terminate the end of the beam stop with a short focal length spherical lens mounted in the tip.  The optical power density at the surface of this laser illuminated lens would be high enough for burning through materials contacting the spherical lens at the tip, but would rapidly fall off with distance due to fast defocusing.

When high enough power lasers become available, the tip of a tungsten beam stop rod can be thermally isolated from the shaft and configured to heat up by direct laser heating and simply melt through objects you want to drill by physical contact.

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--Are these suitable for sparring or fencing?--

Only if you are part of a social circle that also spars or fences with running chain saws and sharpened live steel swords.

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--Are these usable for Cosplay or cons?--

Definitely NO due to the accident possibilities involved when mixing chaotic festive crowds, with hand held high power lasers having externalized beams capable of blinding, cutting and setting fires.

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--What are the safety issues involved in building one of these laser cutting tools?--

 


Lasers in watt class power levels and up are dangerous period.

Laser beams in the watt power level and up are capable of setting objects on fire and if swept across your eyes can cause permanent eye damage including permanent blindness faster that your blink response can protect you.

Even the reflection off of a glass window of a watt class laser can cause permanent eye damage.

High quality laser safety glasses tuned for the laser wavelength you are working with are an absolute non-negotiable piece of gear that must be worn whenever a device containing a high power laser emitter is handled even with the power off.   All people in the same room with a high power laser must also be wearing the appropriate laser safety glasses.

On the work bench, powered laser devices being worked on are always mounted rigidly on a stand, with the laser emitters directed towards a beam stop plate capable of absorbing the full power of the laser without generating hazardous reflections.

The test room where the laser cutting tools are allowed to be free-hand manipulated have the walls and floor covered with plywood painted with non-reflective black flame retardant paint, and heavy wool non-reflective black curtains that have been verified to smolder and char and not ignite when hit by an accidentally misdirected beam.

 


When the laser cutter is not in use, it is stored with the batteries verifiably removed (note the transparent battery holder tube) and the key for the laser actuation key switch is also removed.  A set of laser safety glasses is laid out on top on the cutter handle as a reminder to put on laser safety glasses before handling the laser cutter tool.

There are just some of the basics safety procedures used to stay safe when working with high power lasers.  If you want to work with devices containing high power lasers, educate yourself well about laser safety either through formal training or extensive reading to avoid injuring yourself or others.

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--What are the legal issues for owning, buying or selling one of these laser cutting tools?--

Law regulating the ownership and use of lasers vary a lot depending upon where you live.  Among different countries, it ranges from zero regulations, to portable lasers of greater power than 1 milliwatt (low power laser pointers) being legally classified as weapons equivalent to firearms.

In the USA where I live, you can build, own and use any type of laser of any power you want provided that you operate it in a way that the general public is protected from being exposed to the beam. 

Manufacturing and selling lasers however is heavily regulated.

Laser Pointer Safety - Rules and regulations in the U.S. (For those selling



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--Is this a real lightsaber? / Are you trying to build a real lightsaber?--


Since these prototype safety enhanced laser cutting tools have no demonstrated or theoretical ability to stop force lightning or deflect blaster fire they obviously cannot be considered to be real lightsabers or attempts to build one.  They just coincidentally look like lightsabers.

All of the design features that went into building these laser cutting tools are present due to their ability to enhance operator and bystander safety.

Any resemblance that these safety enhanced handheld laser cutting tools may have to the trademark or copy write protected intellectual property belonging to any multi-billion dollar corporation is unintentional and purely coincidental. 
« Last Edit: March 02, 2017, 07:38:31 PM by Photonic Bladesmith »

Offline Sethski

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Re: Safety Enhanced Handheld Laser Cutting Tools
« Reply #1 on: August 07, 2016, 07:17:11 AM »
Scary/exciting/interesting stuff - loving the extend/retract!

Offline Greywolf

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Re: Safety Enhanced Handheld Laser Cutting Tools
« Reply #2 on: August 10, 2016, 01:19:52 AM »
Impressive work, kudos!
Life is but a series of missed opportunities.

Offline Elzilcho

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Re: Safety Enhanced Handheld Laser Cutting Tools
« Reply #3 on: April 16, 2017, 02:56:30 PM »
Very cool thread/work. I was wondering if the inclusion of the new carbon nanotube forest substrate known as vantablack as opposed to florescent covering on the tungsten would make this a tool that would scatter far less (dangerous) radiant light. As I understand it, the vantablack will absorb 99.975% of light it encounters, and I have seen a video of a laser shine on it wherein there was no red Dot on the surface of the vantablack. I know at this point in time only NASA and the DOD have access to it but someday I believe it would be an invaluable addition to your tool, for safety reasons. Sorry to ressurect this post, but I feel like this would be an interesting idea to attempt.....One day.

 

retrousse