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DIY Spectrometer - Check what wavelengths your lights give out

Icemud

Member of the Month: July 2012, July 2014 - Nug of the Month: July 2012
Hey everyone...

I did not invent this idea but I did want to share it here at 420 Magazine, since it applies to growing. I learned how to make a Spectrometer on You Tube, but its really quite simple so I will try to explain.

What it is:
A spectrometer to put it quite simple, takes the light you see (sun, HPS, MH, lightbulb..whatever) and breaks it apart so that each spectrum of light is visible... When you buy a HID bulb and are looking at the spectrum charts, you are basicly looking at a similar image of what you would see through a spectrometer.... Like looking at a rainbow...

Now What do you need...

A cereal box..
A silver cd or cdr...you could use colored ones but wont get a good refection.
scissors
packing or duct tape
a light source
eyes
marker

How do you make it:

Take the cereal box..*empty of course* and tape up the open end with duct tape...make sure you tape it closed good so that all light would be blocked out...

Next...

Now take the closed cereal box and flip it around so you are looking at the factory sealed end. Along the long, skinny side of the box...measure about 2" from the factory sealed end and draw a line from front face to back face (across the skinny side of the box)

After you have your line on the skinny side of the box...Cut a slit across the skinny side of the box, where you placed the line. Now that you have a slit across this area... you are going to (on each side of the slit) cut downwards and away from the "factory sealed" side of the box, at about a 45 degree angle... Cut about 2-3" down on each side... This is where you are going to slide the CD, with the silver shinny reflective side facing the "factory sealed" side of the box..

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After you have your CD inserted in the box...

On the factory sealed side of the box...about 1 1/2 to 2" down you are going to cut an eyehole... it can be square or round, I made mine square for better photo capturing abilities however either will work. Make this eyehole about 1/2" in diameter, enough you can comfortably look through, but not big enough to let a lot of light in..

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After you have your eyehole..

On the long skinny side of the box...opposite the CD and slit you created...
You are going to cut 1 slit in the box, about 1 1/2" from the factory sealed side of the box. You want this slit to have a very clean edge, so use a razor, or my trimming scissors worked well :) The slit should be around 1" long, and wide enough were you could slip a dime (the coin, not the sack.. :) ) through the slit.... This is going to be where you let the light through...

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Now you are done :) take this and look at various light sources through it, its pretty impressive...

Here are some photos of my bulbs...Take a notice at the peaks on the following charts, and then look at the brightest bands on the photo's I took, see how close they are...

Ushio Optiblue 400w MH
The Chart is first, my photo 2nd

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Ushio_Optiblue.JPG


Here is the Chart for the 400w Ceramic Metal Halide and a Typical HPS bulb
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Now look how the spectrometer picked up the light frequencies..

Ushio OptiRed 600w HPS (running at 400w)
Ushio_Optired.JPG


Phillips RetroWhite 400w CMH
Ceramic_MH.JPG
 
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Icemud

Member of the Month: July 2012, July 2014 - Nug of the Month: July 2012
By using this new home made spectrometer, I determined that for veg, the UshioMH will be my best option for veg, being that it has a very heavy blue end of the spectrum, where as the CMH has a more heavy red end. I will switch my CMH back into the mix near flowering to promote more stretch when I want the stretch...
 

Icemud

Member of the Month: July 2012, July 2014 - Nug of the Month: July 2012
I found it pretty useful, I actually am looking into buying a bi-spectrum induction light, so that is why I built it, so I can check the spectrum to see if it is worthy of purchase...
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
Nice. But... Why not just buy a prism?

Not that this won't work - it obviously does, and the DiY aspect makes it even more appealing.

But I think you'd get a clearer picture with a prism (~$4-$12 for acceptable ones). Less chance of multiple image splits/reflections/re-splits. Less chance of any coloration in the CD - perhaps too subtle for the eye to notice/register - affecting the chrominance(?) of your results. And no chance that the CD would either absorb or attenuate some of the color components.

It's interesting enough that I'll probably build one to play with though.

+REPs.
 

Icemud

Member of the Month: July 2012, July 2014 - Nug of the Month: July 2012
Nice. But... Why not just buy a prism?

Not that this won't work - it obviously does, and the DiY aspect makes it even more appealing.

But I think you'd get a clearer picture with a prism (~$4-$12 for acceptable ones). Less chance of multiple image splits/reflections/re-splits. Less chance of any coloration in the CD - perhaps too subtle for the eye to notice/register - affecting the chrominance(?) of your results. And no chance that the CD would either absorb or attenuate some of the color components.

It's interesting enough that I'll probably build one to play with though.

+REPs.
Thanks TS for your comments...much appreciate the rep too :)

The reason I didn't buy a prism, because this DIY cost me nothing at all to build, vs going to the "prism store", whereever that is, and buying one for $$. If you don't want coloration, use a silver cd-r with clear plastic. I don't imagine this effecting the chrominance of the visible color because it is doing the exact same thing as a prism.

This method hosts less glass for the light to travel thru, so I would assume with light loss thru a prism glass would be more than thru 1mm of clear plastic. (same reason mylar reflects better than a mirror) There is a chance that there may be slight light loss, but were not conducting physics experiments here, just making a cheep useful tool that will give us a real work observation of existing light, refracted into its wavelenghts. (good point though TS :) )

If you tape up the box good enough, and create a very fine slit for the light to enter, there is very little chance that you will get multiple light sources involved in the refraction. The photo's that I posted actually give a pretty good idea what you see inside the box...however, in real world, the image was much clearer, I had a hard time focusing my camera into the box to get a clear image.
 
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Icemud

Member of the Month: July 2012, July 2014 - Nug of the Month: July 2012
Anyone had fun making one of these? if you have, snap some photo's of what your light's are putting out, and list what type of bulb, so others can see what types of spectrum's different lights are outputting :)
 

norman

New Member
Nice. But... Why not just buy a prism?

Not that this won't work - it obviously does, and the DiY aspect makes it even more appealing.

But I think you'd get a clearer picture with a prism (~$4-$12 for acceptable ones). Less chance of multiple image splits/reflections/re-splits. Less chance of any coloration in the CD - perhaps too subtle for the eye to notice/register - affecting the chrominance(?) of your results. And no chance that the CD would either absorb or attenuate some of the color components.

It's interesting enough that I'll probably build one to play with though.

+REPs.

Also, prisms and diffraction gratings spread out the spectrum very differently- diffraction gratings (like the CD here) spread the light out evenly (but give rise to secondary and tertiary refractions- not real important here- you just get a weaker duplicate spectrum), while prisms compress the red end (but are more efficient overall- not important here).

I'm all for McGuyvering...
 
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Icemud

Member of the Month: July 2012, July 2014 - Nug of the Month: July 2012
Anyone made one of these and tested their lights? I would love to see the spectrum outputs of LED's and Induction lights.
 

Icemud

Member of the Month: July 2012, July 2014 - Nug of the Month: July 2012

donpaul.p

Member of the Month: Aug 2013
ok,

ill give it a try tomorrow when i get up, i got some blank cds i can use so ill use the clearest as some are tinted blue but i got stacks of different blanks cd and dvd rw so ill try a few different ones and see what results i got,

if i can take some pics then ill post them up here, ill at least post the build and end results plus im sure my new phone is good enough to take pics with so should get some pics, or maybe a vid, ill see what works best.

great idea i sent you some reps in your journal, ill check out the dual spec hps with it tomorrow and see whats thats showing.

so i take it you hold the small slit close to the bulb so it lets the light in or does it have to be some distance a way from the bulb or dont it matter, im only asking due to the hood reflecting the light back down through the bulb, i really dont know if this will make any difference to the resutls but thought id ask just in case
 

donpaul.p

Member of the Month: Aug 2013
just uploading some pics now but basically this is what i can see.

it has 2 different spectrums show up on the cd, the top is like a mixed spectrum but high in blue colours, then just below that is a solid line of red light which im guessing is the hps part of the light and the blue is the dual spectrum element, let me upload and ill show you what im on about, i had to use 2 different cds, once just gave me a white light and no spectrum, the other cd gave me a full spectrum and this extra strip of red, im just looking for other cds to try, im wondering if we could make the viewer smaller so their is less chance of the light bouncing around inside the box.
ill have a play around and see what i can come up with,

give me 2min and ill put some pics up
 

donpaul.p

Member of the Month: Aug 2013
some pretty amazing pics,

have a look see what you think, this is from a 400watt dual spectrum sunmaster hps bulb

i found you have to get the box at the right distance from bulb, if its to close you dont get any spectrum, plus you need to get the angle right as well, i found that the hps was 3 to 4 ft high and i was kneeling on the floor, then i got the spectrum i got, if i was closer it hardly showed anything at all,

hopefully i got it right and this is the spectrum from the bulb, the cd i used is the shiny silver type so no blue or any other colour in the back of the cd
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this was my first attempt below, dont make the same mistake and make sure you turn the flash off, i took the pics using the new samsung s3 or what ever its called.
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let me know if you think i done it right or not, mine seems to be rainbow shaped, i cut the slit using a scalpol and its pretty thin but quite long, maybe to long but i can tape it up and make it shorter if im doing it wrong, the only light on was the hps, no other light source present
 

donpaul.p

Member of the Month: Aug 2013
its difficult to get right, i couldnt get a reading off of my cfls but maybe their not bright enough, not sure if i did it right so hoping them pics above are how its suppose to be done,

also make sure you use the right blank cd or dvd, i had to try 3 different ones before it would work properly
 

donpaul.p

Member of the Month: Aug 2013
Hi all,

has anyone else give this a try yet, it would be great if we could have different lights tested and we can then compare the results, ill try it with cfls tomorrow and see if i can get anything from them, i didnt get any results last time i tried but i found its difficult to get the angle right, i found theirs a sort of sweet spot that gives the results and i noticed it wasnt with the holes directly lined up with the bulb, i had to be at a slight angle to get good results, maybe my holes wasnt strait or big enough.
 
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