Hello, light freaks: UV radiant intensity of the sun at earth surface

In summary, the speaker is seeking help in estimating the amount of UV radiation coming from a mercury short arc lamp in a fluorescence microscope compared to that of the sun. They are trying to determine the appropriate eye protection to use when adjusting the microscope's light. The speaker also mentions converting the values of radiant intensity to irradiance values and considers using special UV eye protection based on their findings. They also mention the importance of blocking UV light from reaching the eye while working with lab sources.
  • #1
Zellbiologie
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Hello! could you help me with this? I´m from biology field and have some difficulties with the following calculation: I want to estimate how much mor UV is coming from a mercury short arc lamp of a fluorescence microscop compared with the sun UV, so that I use the right eye protection for adjusting the microscip light. Maybe just normal sunglasses are enough, but I want to be sure.

When adjusting, you look into the reflected light of the lamp that is inside of a cover. The reflected light on a wall at aprox. 3 m.

So I try to compare the radiant intensity of UV-A -B and C of the mercury short arc lamp (HBO) with those of the sun.

I have the following radiant intensity values per 1000 cd:

220-280 nm UVC = 0,317 W/sr

280-315 nm UVB = 1,165 W/sr

315-380 nm UVA = 2,10 W/sr

Lamp light intensity is 230 cd.

Now I want to convert the values of Radiant intensity (W/sr) in irradiance values. For example the lamp irradiance at a distance of 1 cm. I get 483 mW/cm² for UVA. Is this right?? That means I get much more UV than that coming from the sun at see level (I find in google a value of 0,5 mW/cm²) and should choose not a sunglass but a special UV eye protection.

Thank you very much!

Mara.
 
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  • #2
UV light from *any* lab source needs to be blocked from reaching the eye, period. There are several ways to do this- goggles, enclosing the light path (some microscopes have a small louvered filter located near the objective).

If you have never aligned a lamp before, find someone who has and get them to show you how- I know several metrology techs that burned their eyes using small Hg penlights because they weren't familiar with the risks and mitigations.
 
  • #3
Thank you Andy for your kind advise. I am taking it into account.
Mara.
 

1. What is UV radiation?

UV radiation is a type of electromagnetic radiation that is emitted from the sun and other artificial sources. It is divided into three categories: UVA, UVB, and UVC. UV radiation is invisible to the human eye, but can have harmful effects on the skin and eyes.

2. How does the sun's UV radiation affect us?

The sun's UV radiation can have both positive and negative effects on our health. On one hand, it helps our bodies produce vitamin D. On the other hand, overexposure to UV radiation can cause sunburns, premature aging of the skin, and even skin cancer. It is important to protect ourselves from excessive UV radiation exposure.

3. What is the UV Index?

The UV Index is a scale that measures the intensity of UV radiation from the sun. It ranges from 0 to 11+, with 11+ being the highest level of UV radiation. The higher the UV Index, the greater the risk of UV exposure and potential harm to our skin and eyes.

4. How is the UV Index calculated?

The UV Index is calculated using a complex formula that takes into account factors such as the time of day, cloud cover, and ozone levels in the atmosphere. It is typically higher during the summer months and at higher altitudes.

5. What is the UV radiant intensity of the sun at Earth's surface?

The UV radiant intensity of the sun at Earth's surface varies depending on several factors such as time of day, location, and atmospheric conditions. On average, it is estimated to be around 1000 watts per square meter, with higher levels during peak sun hours and in areas closer to the equator.

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