Easy HAZ™ Basic

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 HAZ^TM 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 HAZ^TM BASIC calculates MPE, Optical Density, Intrabeam NOHD, and worst case Diffuse Reflection NHZ for CW, Single Pulse, and Repetitive Pulse lasers.

EASY HAZ^TM BASIC Tutorial

This is just to get you started. Click the EASY HAZ^TM icon to open a new window.

1. You can choose to enter the laser wavelength in nanometers or microns (micrometers).

2. Type the Laser Wavelength in the chosen units. Then hit your mouse left button or the tab key.

3. Laser mode of operation can be Continuous Wave, Single Pulse, or Repetitive Pulse. Choose your selection and you will be prompted for parameter inputs. You can use decimals or basic notation. (0.001s is equivalent to 1e-3 s)

4. Use 1/e^2 beam diameter and divergence if you are entering values from a manufacturer's laser data sheet.

5. Once you have entered all the input parameters, the basic hazard analysis values will appear in the Report Section. The values reported are:

Small Source Ocular MPE (J/cm2 for sp; W/cm2 for cw and rp)

Optical Density of Eyewear for worst case exposure

Intrabeam Nominal Ocular Hazard Distance

Small Source Diffuse Reflection Nominal Hazard Zone

6. If you change an input, the output will be updated instantly.

Pretty easy. (See helpful hints below)

Other Calculations Using EASY HAZ^TM BASIC

EASY HAZ^TM BASIC can be used to determine other hazard distances. Enter the laser wavelength in nm and follow the directions below. In each case the specified hazard distance will be displayed in the space for the Intrabeam NOHD.

Calculating Lens-On-Laser NOHD

To find the LOL NOHD:

choose a beam diameter of 0.1 mm and

a beam divergence of 1000b/f mrad

where b = beam diameter on the lens

and f = focal length of the lens

Calculating the Multimode Fiber Optic NOHD

To find the multimode FO NOHD:

choose a beam diameter of 0.1 mm and

a beam divergence of 1667NA mrad

where NA = numerical aperture of the fiber

Calculating the Single Mode Fiber Optic NOHD

To find the single mode FO NOHD:

choose a beam diameter of 0.1 mm and

a beam divergence of 1273L/w mrad

where L = wavelength of the laser

and w = mode field diameter of the fiber in the same units as the wavelength

Calculation of Modified Diffuse Reflection NHZ

The Diffuse Reflection NHZ calculated is for a reflectivity of 100% and a viewing angle of 0 degrees.

You can find other Diffuse Reflection NHZ values by multiplying the power by RcosV

where R = Fractional Reflectivity (R=1 for 100%)

and V = Viewing angle in degrees.




Enter a power that is 0.1 times the laser power, and the value given for Diffuse Reflection NHZ will be for viewing a 20% diffuse reflection at 60 degrees.


EASY HAZ^TM BASIC: Hazard Analysis Tool

Additional Useful Notes

For pulsed lasers, shorter pulses result in a lower MPE and a greater hazard.

For repetitive pulse lasers at a constant average power, a lower pulse rate results in more energy per pulse, leading to a higher peak power and a greater hazard.

If you have a Q-Switched laser but you don't know the pulse duration, choose 100 ns (1e-7 s). The MPE is the same for pulse durations from 1 ns to several µs.

Beam diameter and beam divergence affect Intrabeam NOHD only. If you don't know these values, make your best guess. For most lasers 1 mm and 1 mrad will give you a worst case value of Intrabeam NOHD. If your laser beam is blue, use 0.5 mrad.

More detailed information on laser hazard analysis will be available here in the future. If you have a question, e-mail us, or better yet, take our Applied Laser Safety course and learn all about basic laser hazard analysis.

Now give it a try. You're ready to use EASY HAZ^TM BASIC.