Laser Hazard Analysis Calculations

madmacmo · 02-05-2012, 07:46 PM

Encyclopedia of Laser Physics and Technology - Laser Safety

Quote:

Laser beams can be hazardous, particularly for the eye (and sometimes also for the skin), mostly because they can have high optical intensities even after propagation over relatively long distances. Even when the intensity at the entrance of the eye is moderate, laser radiation can be focused by the eye's lens to a small spot on the retina, where it can cause serious permanent damage within fractions of a second – even when the power level is only of the order of a few milliwatts. Damage can result from both thermal and photochemical effects. Laser damage of the eye is not always immediately noticed: it is possible e.g. to burn peripheral regions of the retina, causing blind spots which may be noticed only years later.

Princeton University - SECTION 2: LASER HAZARDS

Quote:

Beam-Related Hazards
Non-Beam Hazards
The hazards of lasers may be separated into two general categories – beam-related hazards to eyes and skin and non-beam hazards, such as electrical and chemical hazards.

Note the following links providing a selection of straight forward apps and some simple calculations for determining degrees of laser illumination hazard.

Easy HAZ

Quote:

We think basic, reliable, user-friendly laser hazard analysis calculation software should be available for all laser users as a service to the laser community. It's one more thing that gets taken care of better if laser users do it themselves. So we have. EASY HAZTM BASIC does the most essential laser hazard analysis calculations and is designed to give users with minimal hazard calculation experience the most useful information in the simplest format. The emphasis is on easy. EASY HAZTM BASIC calculates MPE, Optical Density, Intrabeam NOHD, and worst case Diffuse Reflection NHZ for CW, Single Pulse, and Repetitive Pulse lasers.

Laser Pointer Safety - Laser safety calculations

Quote:

This page presents laser safety equations and example calculations. These are valid for the type of lasers commonly misused by the general public: laser pointers and commercially available handheld lasers. Specifically, this means lasers emitting visible light (400-700 nanometers) that is continuous (e.g., not pulsed lasers).

Note within the link below reference being made to this previous LPF discussion ^^Blindness Post#46 concerning the apparent and seemingly counter intuitive lack of flash blindness effect by 445nm blue lasers.

Laser Pointer Safety - Different lasers' hazards compared

Quote:

Note for careful readers (such as those at LaserPointerForums.com): Some observant people have noticed that there is no flashblindness distance indicated for the 1W blue handheld (e.g., no red part on the bottom bar). This is because the flashblindness distance of this laser is only 646 feet. That’s shorter than the 733 feet which is the eye injury hazard distance. Here’s how to think of this. The laser’s blue color appears relatively dim to the human eye. Beyond 646 feet it doesn’t appear bright enough to cause flashblindness, yet it is still within the eye injury hazard distance of 733 feet.

Note the link to laservisuals.com below that steve001 posted about here:Re: How far is far enough for the human eye?
Laser Visuals - Scanguard laser show analysis software : Lite Version

Quote:

Scanguard Lite has been designed to introduce the user to key laser safety concepts and the help aid in basic laser safety assessments. The best thing is that it is available free of charge as a request from this website, meaning that even if you are not quite sure if laser safety is something that you need to be concerned with, you can access a useful software tool without having to spend any real money.

Note the links to the iPhone Laser Hazard Calculation Apps below that ElektroFreak posted about here: Re: How far is far enough for the human eye?
Laser Hazard Distance iPhone App
iTunes Download Link - Laser Hazard Distance - id460996018 - Free

Quote:

Laser Hazard Distance is an easy to use laser safety calculator that can be used to help determine the safe viewing distance for direct exposure to visible laser beams. The light created by a laser beam is far more concentrated than other forms of light, and if viewed directly can be harmful to eyesight. The energy in a laser beam however becomes less harmful the further along the beam the light travels, eventually reaching a point where the laser risk is low. Laser Hazard Distance can be used to help determine this distance which is known as the Nominal Ocular Hazard Distance or NOHD.

Laser Show Safety
iTunes Download Link - Laser Show Safety - id452579944 - $6.99

Quote:

Laser Show Safety allows the exposure safety of a wide range of laser show effects to be checked against safe exposure limits, helping to reduce the chance of harm occurring as a result of excessive exposure to beams too strong to enter the eye.

Other Laser Hazard Analysis Links:
Nominal Ocular Hazard Distance and Area
Laser Hazard Analysis for LUMETRICSTM OptiGauge Measurement Probe Super LED
Download LaserSafe PC Demo Version
Eye-Safety Analysis Of Current Laser-Based Scanned-Beam Projection Systems

Princeton.edu - Eye Absorption Site vs. Wavelength

Quote:

The wavelength determines where the laser energy is absorbed in the eye.

Quote:

Lasers in the visible and near infrared range of the spectrum have the greatest potential for retinal injury, as the cornea and the lens are transparent to those wavelengths and the lens can focus the laser energy onto the retina. The maximum absorption of laser energy onto the retina occurs in the range from 400 - 550 nm. Argon and YAG lasers operate in this range, making them the most hazardous lasers with respect to eye injuries. Wavelengths of less than 550 nm can cause a photochemical injury similar to sunburn. Photochemical effects are cumulative and result from long exposures (over 10 seconds) to diffuse or scattered light. Table 3 summarizes the most likely effects of overexposure to various commonly used lasers.

Edit: The former sections below have be relocated here - Get Some Safety Goggles Now!

Notable Level of Hazard Posts
Laser Eye Strikes & Vision Impact Posts
Proof Goggles Are Worth It

InfinitusEquitas · 03-05-2012, 03:16 PM

Awesome post for the research lazy.

+2

Asked c0ld to sticky it.

madmacmo · 03-05-2012, 10:52 PM

IE,

Thanks for the +Rep and I am glad to hear this info has been found to be of value.

The sites to which I referenced in my above post provide quality research information as well as valuable Web based laser hazard assessment tools. And did I mention the added bonus that two of these assessment tools are available for free? I must say these dedicated individuals (who are members of our extended laser community) deserve commendations for putting forth the time and effort to allow the rest of us to stay informed and knowledgeable about laser hazards.

Ontologian · 03-27-2012, 09:36 PM

http://www.lia.org/uploads/pdf/CLSO%...20revision.pdf
This is laser safety officer exam manual. There were no revisions from the 2010 - 2011 from what I know.
I know this is floating around somewhere, but it is nice to have it next to the other information.
The meaning of anything not understood is widely available in physics books concerning optics. Any engineering university will have books on optics.
That is how they compute some of the safety considerations though.
Nice collection MadMacmo

Thanks!

03-05-2012, 03:16 PM	#2
InfinitusEquitas Class 4 Laser Join Date: Mar 2011 Location: 20 Minutes from NYC. Posts: 11,380 Rep Power: 319	Re: Laser Hazard Analysis Calculations Awesome post for the research lazy. +2 Asked c0ld to sticky it. __________________ REQUIRED READING; Sam's Laser FAQs STILL HAVE QUESTIONS? SEARCH FIRST ASK QUESTIONS LATER! LPF Search Tips Link: SHIPPING TIMELINES BY COMPANIES AND REGIONS Link: REVIEWS DO'S and DON'TS YES YOU DO NEED TO GET GOGGLES! YOU ONLY GET TWO EYES, SO GET SOME SAFETY GOGGLES NOW! OEM Laser Systems Laser Safety Industries Thor Labs Suvival Laser Better Than Nothing: Cheap Safety Goggles Last edited by InfinitusEquitas; 03-05-2012 at 03:18 PM.

03-05-2012, 10:52 PM	#3
madmacmo Class 2M Laser Join Date: Dec 2009 Location: Oklahoma USA Posts: 776 Rep Power: 165	Re: Laser Hazard Analysis Calculations IE, Thanks for the +Rep and I am glad to hear this info has been found to be of value. The sites to which I referenced in my above post provide quality research information as well as valuable Web based laser hazard assessment tools. And did I mention the added bonus that two of these assessment tools are available for free? I must say these dedicated individuals (who are members of our extended laser community) deserve commendations for putting forth the time and effort to allow the rest of us to stay informed and knowledgeable about laser hazards.

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03-27-2012, 09:36 PM	#4
Ontologian Junior Member Join Date: Mar 2012 Location: Duluth, Mn Posts: 12 Rep Power: 0	Re: Laser Hazard Analysis Calculations http://www.lia.org/uploads/pdf/CLSO%...20revision.pdf This is laser safety officer exam manual. There were no revisions from the 2010 - 2011 from what I know. I know this is floating around somewhere, but it is nice to have it next to the other information. The meaning of anything not understood is widely available in physics books concerning optics. Any engineering university will have books on optics. That is how they compute some of the safety considerations though. Nice collection MadMacmo Thanks!