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desktop spectrometry kit 3.0

This is a revision from February 12, 2015 04:19. View all revisions
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The Public Lab Desktop Spectrometry Kit 3.0 is the latest version of the spectrometer. Read more about our Spectrometry program, the Oil Testing Kit it is is a part of, or the history of development. Previous versions 2 & 2.5 are here.

Parts List

IMG_20150116_183204-annot.png

click here to see a longer illustrated parts list.

  • Two-piece box
  • "gumstick" webcam with USB cable. datasheet: Spec_of_JDEPC-OV04_Ver_1.01.pdf
  • extra paper for modifications
  • 45 degree wooden (ash) camera block, 3 cm x 4 x 4cm
  • Wooden (ash) bench 1/4" (6mm) x 40mm x 235mm
  • a 65-degree fold up collimation angle
  • a 45-degree fold-up camera angle.
  • 50cm of 3/4" (2cm) width adhesive-backed loop fastener (Velcro-style)
  • 25cm of 3/4" (2cm) width adhesive-backed hook fastener (Velcro-style)
  • DVD-R
  • photo emulsion printed slit 0.2mm wide printed on .004" acetate. files on github
  • 6 yard roll of 1/8" Thermoweb Supertape double sided tape. (3mm)
  • printed assembly instructions (below)

Using your spectrometer

Once you've assembled your spectrometer and are ready to use it, plug it in and visit SpectralWorkbench.org to begin recording data with it. The web-based software works in the Chrome, Firefox and Opera browsers on most computers and Android phones.

(Peer) Support

Public Lab is not a corporation; we're an open community of DIY environmental science researchers which you have just joined! The best place to get help is the spectrometry mailing list; to join, sign up in the form to the left.

The spectrometry mailing list is made up of people like you, who are building and improving open source spectrometry techniques. Ask questions, look for help, and consider helping others too!

You can also post a question on this site; it helps to share some photos or screenshots of what you're trying to do:

Ask a question about spectrometry or Sign up to answer questions on this topic

Resources

Activities

here are the series of notes printed on the spectrometer. notes below by: @amysoyka, @straylight, @wagnerc4, @ygzstc, @cfastie, @stoft, & @Alex-McCarthy.

This spectrometer design:

Spectrometer development:

Activities:

Assembly

Your spectrometer is composed of three functional elements:

  • a collimation slit that works as a lens, only allowing parallel light rays through its apeture.
  • a diffraction grating that deflects light more the lower the light's wavelength, creating a rainbow diffraction pattern.
  • a camera to capture the diffraction pattern, focused on the collimation slit.

arrangement_illustrated-labeled.jpg

These elements are mounted on an adjustable velcro bench in a black paper box.

IMG_20150210_143526_corrected-labeled.png

Putting velcro on the bench

Everything is built up from the bench, an ash board 4cm (1.75 inches) wide. We will cover it with the "loop" side of the velcro.

IMG_20150210_160302-edit.jpg

velcro-labeled.png

The velcro loop tape is slightly wider than half the width of the bench, two strips will hang over each edge a bit.

IMG_20150210_160318-edit.jpg

Assemble the camera block

You will need the camera, double-sided tape, the block, and the hook side of the velcro tape. Try to hold the camera by its edges, as it can be sensitive to electrical shorts.

IMG_20150210_150024-ed-labels.png

Start by putting a strip of double-sided tape on the back side of the camera:

IMG_20150210_150202.jpg

Remove the pink protective film from the double-sided tape and attach to the center of the block's 45-degree angled side, with the white cable port on top:

IMG_20150210_150230.jpg

IMG_20150210_150258.jpg

On the underside of the block, attach two short strips of the velcro hook tape.

IMG_20150210_150318.jpg

Make a diffraction grating from a DVD

Do not touch the surface of the DVD, always hold it by the edges, fingerprints will blur this important optical component.

We are going to turn a DVD-R into a diffraction grating. An ideal diffraction grating would create a straight rainbow. A DVD produces a curved rainbow, but its rigidity and consistency make it a very good grating.

ideal-vs-dvd-grating-ed.png

We have three steps, cutting a quarter of the DVD out, peeling off the reflective aluminum side, and triming to a small piece.

cutpeeltrim-labeled.png

OPTIONAL: Wash the purple ink off of the DVD fragment for greater light transmission. see note /n/11515.

Peeling apart a quarter of the DVD:

Cutting out a quarter of the DVD with scissors. It may take more than one try to get a good diffraction grating, so save the rest too.

Use a knife or a fingernail to dig under the corner of the DVD quarter and peel the two layers apart.

IMG_20150210_144414.jpg

IMG_20150210_144530-trim.jpg

You will get two layers. We are trying to get a transparent purple piece without aluminum stuck to it. Some may get stuck to the sides, but we only need a 2cm (.75") square cut from the outer edge.

IMG_20150210_144232-labeled.png

Trim down to a small square with roughly 2cm of the DVD's outer edge.

2cm-label.png

Assemble the diffraction grating angle

You will need:

IMG_20150210_145901-labeled.png

Overview:

IMG_20150210_145742-ed-labeled2.png

IMG_20150210_145304ed.jpg IMG_20150210_145343ed.jpg

Make sure the bottom flaps are lined up.

IMG_20150210_145436ed.jpg

put hook tape on the bottom.

IMG_20150210_145536ed.jpg

Put the outer edge of the dvd at the mid-point of the hole, and then remove the handles from the binder clip.

IMG_20150210_145648ed.jpg

Assemble the slit card

You will need:

IMG_20150210_150959ed-labeled.png

The collimation slit should be in the DVD sleeve.

_We will attach the slit using the tape as single sided tape-- tape it on top and DO NOT remove the backing film. _ Line up the collimation slit with the line on the slit card.

Assemble the box

step-by step video:

For the purposes of this instructional I've highlighted the edges of the box.

Place the box with the printing facing down. Pre-crease all the creases.
crease the box top as well.

together1-1.jpeg

together1-3.jpeg

Fold the left side of the box to the right, and insert the hold tab in place.

together1-2.jpeg

Fold the right side to the left and lay the box top on top so its tabs line up with the slots in the box bottom. Make sure the small rectangular holes on the top and bottom line up. We will put the webcam cable through that hole later.

together1-4.jpeg

Insert the tabs together. The box top will not lay flat-- don't worry.

together1-6.jpeg together1-7.jpeg together1-8.jpeg

Pull the box top back to the right and fold the inner walls to the middle.

together1-10.jpeg

together1-11.jpeg

Hook the inner walls together.

together1-12.jpeg

Fold the outer walls up and over the inner walls. Use the two circular holes in the outer walls to position the inner walls while folding the outer wall over.

together1-13.jpeg

together1-14.jpeg

Flip the box upside down and make sure the tabs have all popped out of the bottom of the box. Walk your fingers along the inside of the box and make sure all the tabs are popped out of the bottom.

together1-15.jpeg

Putting it all on the bench

IMG_20150210_143526_corrected-labeled.png

Line up the the bench with the side of the box, and align the camera's lens with the 200mm marker on the side of the box. Press the camera block down firmly.

IMG_20150210_144844ed.psd

Place the diffraction grating angle directly in front of the camera block and press it down firmly.

IMG_20150210_143810.jpg

Slide the slit card in the front of the box. The printing is slightly off, unfortunately. level the slit card's line just above the box's line. the card should wedge in place on its bottom edge.

IMG_20150210_160107.jpg

IMG_20150210_160149ed.jpg

Push the camera cable through the cable hole in the back of the box:

IMG_20150115_200145ed.jpg

Plug it into the camera-- it only fits one way, don't force it.

IMG_20150210_161354ed.jpg

Slide the bench in at an angle, placing it down by the cable hole, and then pushing it down to the bottom.

IMG_20150210_160613ed.jpg

You're done! Your computer should recognize your spectrometer as a webcam.

setup live capture for your spectrometer on Spectralworkbench.org

Design Notes

consult the following notes on development for the evolution of this design. @mathew paper spectrometer 1, paper spectrometer 2