Why Do Some Laser Glasses with Lower Optical Densities have Lower VLT?

Optical density is related to visual light transmission… But some laser safety glasses with lower optical densities have lower VLT, as well.

Laser Glasses with Lower Optical Densities and Lower VLT

Low OD, Low VLT Laser Safety GogglesToday’s lasers operate at a large variety of wavelengths, from 190 to over 10,000 nanometers. The visible light spectrum, on the other hand, falls roughly between 400 and 700 nanometers. Coverage of wavelengths outside the visible light range will not affect your vision, because they’re covering light that you can’t see.

Most laser lenses have some kind of color to them, which means that most laser lenses block at least some visible light. Many lenses, though, are not so dark that they impede your vision while working in well-lit environments.

If you are curious about why some laser lenses with relatively low coverage ranges have low visual light transmission (VLT), here’s what you need to know:

  • Visible light falls roughly between 400 and 700 nanometer wavelengths of light. Any light outside of this range is not visible, so you won’t notice if it’s blocked because you can’t see it to begin with.
  • Light that’s blocked within the visible light spectrum will darken your lenses. If somebody asked for lenses that block 400-700nm at an optical density above 2, the lenses would seem opaque. They would seem to block all visible light, but they would not protect your eyes from invisible beams such as ones operating at 10,600nm.
  • All this is why, if you compare two laser lenses which cover different wavelengths, one might block more light (and could be assumed to be darker) but might actually be crystal clear, while the other is very dark. For instance, laser safety glasses that cover 800-10,600nm at an OD of 7 would seem very clear, but glasses that block 500-700nm at an OD of 2 would seem like a dark pair of sunglasses.
  • Visible light transmission is related to optical density in that, the more visible light is blocked, and the higher the OD (blockage) at those wavelengths, the darker the lenses seem.
  • Light that is blocked outside of the visible spectrum has no bearing on VLT, unless the dyes used to block those wavelengths also happen to block some visible light.

VLT is a tricky thing and can only be calculated using knowledge of visible light and calculus to find the area of visible light blocked beneath a transmission graph. The things to consider are:

  • The human eye is very sensitive and does not need a lot of light to be able to see.
  • Most people can see fairly well in good lighting with 50% or even 70% of visible light blocked (50% or 30% VLT, respectively).
  • Lower than 30% VLT will have a significant effect on your ability to see.

If your laser operates within the visible light spectrum, it is impossible to get laser safety goggles or glasses that are clear.

VLT is important to your work, but should not be sacrificed for safety. If you need laser safety glasses with low VLT, your facility probably has procedures for how to work while wearing the dark glasses.

There should never be a compromise where laser safety goggles are concerned. If you need the protection, it is crucial to wear the right safety glasses. Without them, you risk blindness, eye injury, and death.

Shop Laser Safety Goggles

If you have any questions, feel free to leave them in the comments below or browse some of our other blog posts, and thanks for reading! As always, stay safe!

One Response to Why Do Some Laser Glasses with Lower Optical Densities have Lower VLT?
  1. [...] are other possibilities as well, though. For instance, some glass lenses can have their optical densities increased to a satisfactory level simply by increasing the thickness of the lens. Glass laser [...]

Leave a Reply

Wanting to leave an <em>phasis on your comment?

Trackback URL http://lasersafetygoggles.com/why-do-some-laser-glasses-with-lower-optical-densities-have-lower-vlt/trackback/

Why Do Some Laser Glasses with Lower Optical Densities have Lower VLT?

Optical density is related to visual light transmission… But some laser safety glasses with lower optical densities have lower VLT, as well.

Laser Glasses with Lower Optical Densities and Lower VLT

Low OD, Low VLT Laser Safety GogglesToday’s lasers operate at a large variety of wavelengths, from 190 to over 10,000 nanometers. The visible light spectrum, on the other hand, falls roughly between 400 and 700 nanometers. Coverage of wavelengths outside the visible light range will not affect your vision, because they’re covering light that you can’t see.

Most laser lenses have some kind of color to them, which means that most laser lenses block at least some visible light. Many lenses, though, are not so dark that they impede your vision while working in well-lit environments.

If you are curious about why some laser lenses with relatively low coverage ranges have low visual light transmission (VLT), here’s what you need to know:

  • Visible light falls roughly between 400 and 700 nanometer wavelengths of light. Any light outside of this range is not visible, so you won’t notice if it’s blocked because you can’t see it to begin with.
  • Light that’s blocked within the visible light spectrum will darken your lenses. If somebody asked for lenses that block 400-700nm at an optical density above 2, the lenses would seem opaque. They would seem to block all visible light, but they would not protect your eyes from invisible beams such as ones operating at 10,600nm.
  • All this is why, if you compare two laser lenses which cover different wavelengths, one might block more light (and could be assumed to be darker) but might actually be crystal clear, while the other is very dark. For instance, laser safety glasses that cover 800-10,600nm at an OD of 7 would seem very clear, but glasses that block 500-700nm at an OD of 2 would seem like a dark pair of sunglasses.
  • Visible light transmission is related to optical density in that, the more visible light is blocked, and the higher the OD (blockage) at those wavelengths, the darker the lenses seem.
  • Light that is blocked outside of the visible spectrum has no bearing on VLT, unless the dyes used to block those wavelengths also happen to block some visible light.

VLT is a tricky thing and can only be calculated using knowledge of visible light and calculus to find the area of visible light blocked beneath a transmission graph. The things to consider are:

  • The human eye is very sensitive and does not need a lot of light to be able to see.
  • Most people can see fairly well in good lighting with 50% or even 70% of visible light blocked (50% or 30% VLT, respectively).
  • Lower than 30% VLT will have a significant effect on your ability to see.

If your laser operates within the visible light spectrum, it is impossible to get laser safety goggles or glasses that are clear.

VLT is important to your work, but should not be sacrificed for safety. If you need laser safety glasses with low VLT, your facility probably has procedures for how to work while wearing the dark glasses.

There should never be a compromise where laser safety goggles are concerned. If you need the protection, it is crucial to wear the right safety glasses. Without them, you risk blindness, eye injury, and death.

Shop Laser Safety Goggles

If you have any questions, feel free to leave them in the comments below or browse some of our other blog posts, and thanks for reading! As always, stay safe!

One Response to Why Do Some Laser Glasses with Lower Optical Densities have Lower VLT?
  1. [...] are other possibilities as well, though. For instance, some glass lenses can have their optical densities increased to a satisfactory level simply by increasing the thickness of the lens. Glass laser [...]

Leave a Reply

Wanting to leave an <em>phasis on your comment?

Trackback URL http://lasersafetygoggles.com/why-do-some-laser-glasses-with-lower-optical-densities-have-lower-vlt/trackback/

Why Do Some Laser Glasses with Lower Optical Densities have Lower VLT?

Optical density is related to visual light transmission… But some laser safety glasses with lower optical densities have lower VLT, as well.

Laser Glasses with Lower Optical Densities and Lower VLT

Low OD, Low VLT Laser Safety GogglesToday’s lasers operate at a large variety of wavelengths, from 190 to over 10,000 nanometers. The visible light spectrum, on the other hand, falls roughly between 400 and 700 nanometers. Coverage of wavelengths outside the visible light range will not affect your vision, because they’re covering light that you can’t see.

Most laser lenses have some kind of color to them, which means that most laser lenses block at least some visible light. Many lenses, though, are not so dark that they impede your vision while working in well-lit environments.

If you are curious about why some laser lenses with relatively low coverage ranges have low visual light transmission (VLT), here’s what you need to know:

  • Visible light falls roughly between 400 and 700 nanometer wavelengths of light. Any light outside of this range is not visible, so you won’t notice if it’s blocked because you can’t see it to begin with.
  • Light that’s blocked within the visible light spectrum will darken your lenses. If somebody asked for lenses that block 400-700nm at an optical density above 2, the lenses would seem opaque. They would seem to block all visible light, but they would not protect your eyes from invisible beams such as ones operating at 10,600nm.
  • All this is why, if you compare two laser lenses which cover different wavelengths, one might block more light (and could be assumed to be darker) but might actually be crystal clear, while the other is very dark. For instance, laser safety glasses that cover 800-10,600nm at an OD of 7 would seem very clear, but glasses that block 500-700nm at an OD of 2 would seem like a dark pair of sunglasses.
  • Visible light transmission is related to optical density in that, the more visible light is blocked, and the higher the OD (blockage) at those wavelengths, the darker the lenses seem.
  • Light that is blocked outside of the visible spectrum has no bearing on VLT, unless the dyes used to block those wavelengths also happen to block some visible light.

VLT is a tricky thing and can only be calculated using knowledge of visible light and calculus to find the area of visible light blocked beneath a transmission graph. The things to consider are:

  • The human eye is very sensitive and does not need a lot of light to be able to see.
  • Most people can see fairly well in good lighting with 50% or even 70% of visible light blocked (50% or 30% VLT, respectively).
  • Lower than 30% VLT will have a significant effect on your ability to see.

If your laser operates within the visible light spectrum, it is impossible to get laser safety goggles or glasses that are clear.

VLT is important to your work, but should not be sacrificed for safety. If you need laser safety glasses with low VLT, your facility probably has procedures for how to work while wearing the dark glasses.

There should never be a compromise where laser safety goggles are concerned. If you need the protection, it is crucial to wear the right safety glasses. Without them, you risk blindness, eye injury, and death.

Shop Laser Safety Goggles

If you have any questions, feel free to leave them in the comments below or browse some of our other blog posts, and thanks for reading! As always, stay safe!

One Response to Why Do Some Laser Glasses with Lower Optical Densities have Lower VLT?
  1. [...] are other possibilities as well, though. For instance, some glass lenses can have their optical densities increased to a satisfactory level simply by increasing the thickness of the lens. Glass laser [...]

Leave a Reply

Wanting to leave an <em>phasis on your comment?

Trackback URL http://lasersafetygoggles.com/why-do-some-laser-glasses-with-lower-optical-densities-have-lower-vlt/trackback/

Why Do Some Laser Glasses with Lower Optical Densities have Lower VLT?

Optical density is related to visual light transmission… But some laser safety glasses with lower optical densities have lower VLT, as well.

Laser Glasses with Lower Optical Densities and Lower VLT

Low OD, Low VLT Laser Safety GogglesToday’s lasers operate at a large variety of wavelengths, from 190 to over 10,000 nanometers. The visible light spectrum, on the other hand, falls roughly between 400 and 700 nanometers. Coverage of wavelengths outside the visible light range will not affect your vision, because they’re covering light that you can’t see.

Most laser lenses have some kind of color to them, which means that most laser lenses block at least some visible light. Many lenses, though, are not so dark that they impede your vision while working in well-lit environments.

If you are curious about why some laser lenses with relatively low coverage ranges have low visual light transmission (VLT), here’s what you need to know:

  • Visible light falls roughly between 400 and 700 nanometer wavelengths of light. Any light outside of this range is not visible, so you won’t notice if it’s blocked because you can’t see it to begin with.
  • Light that’s blocked within the visible light spectrum will darken your lenses. If somebody asked for lenses that block 400-700nm at an optical density above 2, the lenses would seem opaque. They would seem to block all visible light, but they would not protect your eyes from invisible beams such as ones operating at 10,600nm.
  • All this is why, if you compare two laser lenses which cover different wavelengths, one might block more light (and could be assumed to be darker) but might actually be crystal clear, while the other is very dark. For instance, laser safety glasses that cover 800-10,600nm at an OD of 7 would seem very clear, but glasses that block 500-700nm at an OD of 2 would seem like a dark pair of sunglasses.
  • Visible light transmission is related to optical density in that, the more visible light is blocked, and the higher the OD (blockage) at those wavelengths, the darker the lenses seem.
  • Light that is blocked outside of the visible spectrum has no bearing on VLT, unless the dyes used to block those wavelengths also happen to block some visible light.

VLT is a tricky thing and can only be calculated using knowledge of visible light and calculus to find the area of visible light blocked beneath a transmission graph. The things to consider are:

  • The human eye is very sensitive and does not need a lot of light to be able to see.
  • Most people can see fairly well in good lighting with 50% or even 70% of visible light blocked (50% or 30% VLT, respectively).
  • Lower than 30% VLT will have a significant effect on your ability to see.

If your laser operates within the visible light spectrum, it is impossible to get laser safety goggles or glasses that are clear.

VLT is important to your work, but should not be sacrificed for safety. If you need laser safety glasses with low VLT, your facility probably has procedures for how to work while wearing the dark glasses.

There should never be a compromise where laser safety goggles are concerned. If you need the protection, it is crucial to wear the right safety glasses. Without them, you risk blindness, eye injury, and death.

Shop Laser Safety Goggles

If you have any questions, feel free to leave them in the comments below or browse some of our other blog posts, and thanks for reading! As always, stay safe!

One Response to Why Do Some Laser Glasses with Lower Optical Densities have Lower VLT?
  1. [...] are other possibilities as well, though. For instance, some glass lenses can have their optical densities increased to a satisfactory level simply by increasing the thickness of the lens. Glass laser [...]

Leave a Reply

Wanting to leave an <em>phasis on your comment?

Trackback URL http://lasersafetygoggles.com/why-do-some-laser-glasses-with-lower-optical-densities-have-lower-vlt/trackback/