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

[Zellbiologie]

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.

 

[Andy Resnick]

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.

 

[Zellbiologie]

Thank you Andy for your kind advise. I am taking it into account.
Mara.