Review of the Directly-Injected 515nm Green Diode Laser Module

Cyparagon said:

You're still not listening. The data is wrong. I've explained to you why already.

Do you have any discharge lamps or glow lamps? Even a fluorescent lamp?

Click to expand...

I have removed the FWHM value & chart.
I shall do so on all future reviews that I post on this BBS.

I have a CFL fluoro running nearby as we speak...let me go perform spectroscopy of it (including capturing a raw spectrometer data file) and see what comes out in the wash.

Spectrographic analysis of the CFL bulb in the small table lamp on the other side of the kitchen table.

The raw spectrometer data (tab-delimited that can be loaded into Excel) is at http://ledmuseum.candlepower.us/44/cfl11.txt

Oh good! :beer:

Now zoom in on that violet line. That's the mercury H-line. It is precisely 404.7nm (source) with a line width of pretty much zero, since it is an atomic transition line. Your spectrometer will show something rather different - not because you are reading something wrong, but because spectrometers are not perfect (especially lower-end ones like you and I have), and they all have their limitations. If we want to be scientifically and statistically accurate, we need to note these limitations and account for them.

Judging by the raw data you linked, you are reading "404.29" nm with a line width of about 2nm. Since we know exactly what to expect from a mercury discharge, we can compare your unit with what is expected, and note the limitations. In your case, statistically, since everything is off by about half a nanometer, you should round off all decimal places since those are not accurate enough to be used. Line widths can still be measured, but only on wide lines, like LEDs.

Good job +4 when I can- PM coming--hak