Hello
I would like to conduct a mock experiment on plant cells nucleotide excision repair. the UV sourse I have is a tube light used in laminar hood.
UV lamp specifications:
emmission @254nm (85% of total radiationis 254)
lamp output is 13.4W
length : 893mm
diameter : 25.5
Apart from these, i have measured illuminance using illuminometer. the mechine is not really geared for UV radiation but i thought i get a rough estimation. at 30 cm distance from lamp it showed 200 lux.
According to literature, 20 J/square meter of UV irradience is opetimal for viability vs labelling efficiency and i would like to start with the same.
Now the information i needed for starting my experiment is :
At what distance for how much time gives 20 J/square meter of UV irradience.
Thank you
I don't think there is a way to calculate this precisely enough. If you are planning to study NER, you should invest in one of those
https://www.tequipment.net/Extech/SDL470/UV-Meter/
and check your light before every experiment as it may change form experiment to experiment.
Hi,
I agree with the previous comment, though you can theoretically calculate the UV dose knowing the lamp output and distance from the lamp, this would only be an estimation.
UV lamps lose intensity over time, and while your specifications may be correct for brand new UV tubes, dependend on their frequency of use, the actual intensity will be lower than what you have calculated.
A quite comfortable alternative is the use of a commercial UV crosslinker device, which generally come equipped with a UV intensity sensor. Those devices are great for reproducible UV dosage, as they allow you to define a specific dose and automatically turn off the lamps as soon as it has been reached. Also, they are quite common in biological laboratories.
And a third comment on this:
Never try to assume the UV intensity by the light emission of an UV emitter. Light emission in a way is wasted energy just indicating that the lamp is running, but it does give not information about the non visible UV energy.
UV output energy is highly dependent of the used respectively fitted electronic ballast and the temperature situation of the emitter. There is only one way: Measurement with an appropriate UV sensor device. A good source for this kind of equipment is: https://sglux.de/en/
The irradiance is 20.03 W/m2 at 101 mm distance from and perpendicular to the center of the lamp axis. This will produce 20 J/m2 at 1 second. This is based on the view factor method given in Kowalski (2009) which is more precise than any photometer you would use to measure it. If you know the expected exposure time I can provide you the proper distance. I also need to know if this is an LP or MP lamp.
Hi Wally.
I am with you, that your model gives a more precise information than a photometer in terms of mathematical correct result. But if I do remember correctly this model is based on an ideal situation for lamp and ballast. That means, it does not take care of e.g. overheating or undercooling of the emitter and also takes it for granted that the connected lamp ballast is the ideal one for the emitter. But correct me if I am wrong.
Correction factors can be used for heating and cooling. Certainly the lamp needs the correct ballast.
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