When it comes to laser safety glasses, Optical Density (OD) is one of the most important specifications to understand. It plays a critical role in protecting your eyes from harmful laser radiation by determining how effectively the glasses block specific wavelengths.
What Is Optical Density?
Optical Density (OD) is a logarithmic measure of how much light at a specific wavelength is attenuated (blocked) by a lens. The higher the OD value, the greater the level of protection. It is expressed as:
OD = log₁₀ (incident power / transmitted power)
For example:
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OD 1 blocks 90% of the laser light
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OD 3 blocks 99.9%
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OD 7 blocks 99.99999%, or 10 million times attenuation
This scale is not linear. Each increase of 1 in OD represents a tenfold increase in protection. For example an OD 7 is 10,000,000X reduction, OD6 is a 1,000,000 reduction and OD3 is 1000X reduction.
Why Is OD Important for Laser Safety?
Different lasers emit light at different wavelengths and power levels. Without the right level of attenuation, exposure to laser beams can cause permanent eye damage. Selecting laser safety glasses with the correct OD rating ensures that the eyewear blocks enough energy to keep your eyes safe during laser use.
For example:
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Low-power alignment lasers may only require OD 1–2
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High-powered YAG or diode lasers typically need OD 6–8 or higher
Always match the OD rating and wavelength range on your glasses to the specific laser equipment you're using.
Certified Protection You Can Trust
All laser safety glasses sold on LaserGlasses.com.au are fully certified to Australian/New Zealand and international laser safety standards, with OD ratings clearly marked on the lenses for your peace of mind.
If you're unsure which OD level is right for your application, our laser safety experts are here to help. Call us on 1300 411 337 or email info@laserglasses.com.au for tailored advice.