DIY spectrometer contd!

[Gasman]

Hi guys

Well I`ve done easier things before .  I decided the diy spectro was quite a bit out of alignment so bit the bullet and decided to do a full alignment.

After much lip biting,breath holding and finger crossing I`ve managed to get the optics aligned (I think) to within 10nm depending on how accurate the very helpful note on the side of the red laser is telling me it emits light at 650nm.

.

Pointing the fibre optic cable at an energy saving bulb i`m wondering if anyone could tell what these peaks shown at 693 and 728nm might be please?

Note - given the possible 10nm out with the laser these peaks might actually be  683nm and 718 nm

Regards

Steve

[TimX524]

Not sure.  I would have thought that the mercury vapour discharge in the low energy bulb would peak at the blue and green lines at 436 and 546 nm respectively.

Was the light you pointed at very red?? I am asking because the spectrum you show peaks at wavelengths longer than the red of the laser.

Visible light is in the range 400 nm to 700 nm. 

T

[Gasman]

It was very red Tim, I just took the wavelength of the laser at face value. The slightest tweak of any of the optics throws the plot off screen so the makers are right to say its not a trivial operation!.

The object is to get the spectrum onto a ccd measuring 1 x 2047 (yes that`s 1 pixel high ) . Maybe more tweaking needed now I know how to do it and those figures you give above may be better to use for the alignment although the peaks I show are only 35nm apart instead of the 110nm apart  you mention above?

I really need some 3rd order coefficients to be entered into the software to get actual calibration but for these I need 4 known lines. Perhaps once I have those the x axis will adjust accordingly!

Steve

[Merlin66]

According to my fluoro lamp spectrum (See Christian Buil's page)....

I think the larger peak may be at 6113A and the secondary the Hg + ? at 5770- 5870.

[Gasman]

Thanks for that Ken. I tried the fluro starter bulb you suggested from Richard Walkers site and modified an old nitelite by removing the Neon bulbs and replaced them with the bulb from the starter with a 24k resistor and now have to try and Id some lines out of this lot

Steve