Please watch this youtube video if you are interested in UV light sources.
I have a Youtube video on the "Overview of the Kinsten PCB UV Exposure Box"
http://youtu.be/j_5iuFjYY5gI have many youtube videos on PCBs and microcontrollers etc.
Please subscribe to the youtube channel if you like.
Tom
--- In Homebrew_PCBs@yahoogroups.com, "bebx2000" <bebx2000@...> wrote:
>
> What you want is a UV radiometer or UV light meter. The measurement is usually mw/cm∗2. The required exposure of the photoresist is usually given in mJoules/cm∗∗2 (1 mJoule = 1 mW for 1 second.). So just take take a measurement at the surface of your PCB divide it into the required mJoules and you have the required exposure time in seconds. Each brand of resist has a different energy requirement. Dig around on the Dupont Riston site for typical values. Dupont generally recommends 365 nm in the spectrum as the sweet spot.
>
> I have the General Tool UV513AB meter
>
> http://www.amazon.com/General-UV513AB-Digital-Ultraviolet-Measurement/dp/B002JOR0JO/ref=cm_cr_pr_product_top
>
> It has NIST traceable certified calibration at 365 nm and really great value for the money. It measures UVA and UVB (280 - 400 nm). You could also make your own using a blue or an UV led as a detector. When used as a detector, the response is usually of the order of 25 to 30 nm less than the the emitted wavelength with a bandwith of about 50 nm. Therefore, a 400 nm UV led should detect pretty close to 370 nm.
>
> Forrest Mims has a design and for the general idea see,
>
> https://www.cs.drexel.edu/~dbrooks/globe/construction/construction_V3.htm
>
> http://laser.physics.sunysb.edu/~tanya/report2/
>
> http://www.patarnott.com/atms360/sunphotometer.htm
>
> The problem with DIY meters is calibration which is why I just bought the cheapest one that I could find.
>
> Baxter
>
> --- In Homebrew_PCBs@yahoogroups.com, Per Mattsson <per@> wrote:
> >
> > Hi guys!
> >
> > How can one measure the wavelengths, either a graph over the spectrum or certain wavelengths of a UV-source?
> > What unit would one use - Watt, Joule?
>