OSAT Monochromator.jpg
FA info icon.svgAngle down icon.svgDevice data
Manufacturing files https://www.youmagine.com/designs/osat-monochromator
Hardware license CERN-OHL-S
Certifications Start OSHWA certification
FA info icon.svgAngle down icon.svgProject data
Authors Anthony Rettig
Andrew Wunderlin
Completed 2018
Made Yes
Replicated No
Cost USD 4.11
OKH Manifest Download

Adjustable Monochromator. A monochromator is a device which takes light and transmits it to into a narrow band of wavelengths. Using a form of mechanical filtering (diffraction) the user is able to select a specific wavelength (color) which would exit through a exit slit. The monochromator holds many scientific applications ranging from measuring a reflected or transmitted light off a surface. By branching two assemblies together, one can produce a excitation wavelength aiming at the second which can analyze the emitted light.

The basis of this project was derived from a early project Bproman and Ajrettig developed based around making an affordable piece of lab equipment. The design used a whole CD which was fixed, thus causing it to struggled to focus the wavelength and the exit slit had to be set manually by sliding a printed shroud. This design used the previous concept with an addition of a rotating reflective surface which aims the wavelength to an exit slit which can be finally adjusted to a desired wavelength.

Previous Design: [1]


New Design:

OSAT Monochromator.jpg

Bill of Materials[edit | edit source]

  • PLA Printing Filament (1 kg) - $14.99 [2]
  • Blank CD (Can be replaced with any CD) 25pk - $7.79 [3]
  • Box Cutter Blade 100 pk - $9.98 [4]
  • M3 8mm Socket Head Cap Screws 25 pk - $3.23 [5]
  • M3 25mm Socket Head Cap Screws 100 pk - $11.79 [6]
  • Ballpoint Pen Spring (any spring) $9.99 100pk - [7]

Download CAD and STLs Here [8]

Tools needed[edit | edit source]

Skills and knowledge needed[edit | edit source]

Technical Specifications and Assembly Instructions[edit | edit source]

Parts (Qty 1 for all)

  • Body2
  • Body Cover
  • Light Slit Left
  • Light Slit Right
  • Light Reflector Gear


  • Material: PLA or Equivalent
  • Support: None
  • Layer Height: 0.2mm
  • Printer Speed: Varies based off Model, choose a speed in order to give best print quality
  • Print Temp: Choose based off material selection for best print quality
  • Specific Part Instruction:


  • Density: 100%
  • Walls: 4

Rest of Components:

  • Density: 15%
  • Walls: 2

Estimated Time - 7 hrs


Estimated Time - 30 min

  1. Take Left and Right Slit, using 3M 8mm screws attach a box cutter blade to each of the components. See Picture below

OSAT Monochromator.jpg

  1. Using a 3M 25mm screw feed it through the hole located on the side of the Right Slit part.
  2. Place the pen spring over the screw
  3. Using the guiding rails, secure the left and right slit. (do not over tighten as this is your calibration screw for the the slit thickness)


  1. Carefully using a sharp blade, cut a small reflective piece out of a CD
  2. Glue the reflective surface to the tab on the larger gear. See picture below for arrangement.


  1. Place the gears on their respective shafts of the body component, these should be loose enough to still allow rotation. Clean up as needed based off printer quality.


  1. Place the slit assembly with the body assembly, this should be a tight fit. See picture below for alignment.
  2. Place the Body Cover over the whole assembly lining up the holes.

10. Secure with M3 25mm screws


How To Use/Adjust

  1. Place a light source at the opening, preferably a single white LED source.
  2. Wavelengths can be adjusted by moving the small gear located in the rear of the assembly.


  1. Slit thickness can be adjusted by tightening or loosening the M3 25mm screw located on the side of the slit assembly.

Common Problems and Solutions[edit | edit source]

Shattering CD - When cutting the CD to size, be sure to use a fresh blade and carefully cut using a straight edge till all the way through the CD.

Reflective Surface - When cutting be careful, reflective surface may flack off or peel. If it occurs cut a new section.

Cost savings[edit | edit source]

Cost of Production

$0.37 - Gear A + B

$0.22 - Light Slit Left

$0.13 - Light Slit Right

$0.70 - Body Cover

$0.99 - Body

$0.31 - Blank CD

$0.20 - 2x Box Cutter Blade

$0.52 - M3 8mm Screw

$0.47 - M3 25mm Screw

$0.20 - 2x Pen Spring

Total = $4.11

Commercial Equivalent

Newport: $5000-$8000 [13]

Edmund Optics - Mini Chrom (Specific Range): $1500 [14]

ScienceTech: $5000-$10000 [15]


Mini Chrom Comparison - 364.96%

Standard Edition Comparison ($5000) - 1217%

Benefited Internet Communities[edit | edit source]

Gathering for Open Science Hardware (GOSH) - [16] - A movement that seeks to reduce barriers between diverse creators and users of scientific tools to support the pursuit and growth of knowledge.

Spiderwort - [17] - A open source group that has released several scientific designs and continues to develop open source kits that could be used in schools, labs and garages.

Open-Labware - [18] - A community that focues on consumer-oriented 3D printers based off the "maker movement" pushing for prototypes of complex products in owns own garage.

PhysicsOpenLab - [19] - A physics based community that openly shares designs for scientific equipment for people to make at home.

SciencetoyMaker - [20] - Focuses on making cheap fun science based toys for children which makes learning fun.

References[edit | edit source]

  1. Monochromators Wiki Available: https://en.wikipedia.org/wiki/Monochromator.html
  2. Shimadzu Corportaion - Monochromators Fundamentals Available: https://www.shimadzu.com/an/uv/support/fundamentals/monochromators.html#2
  3. Castor Classes Youtube.com - Monochromator Video Available: https://www.youtube.com/watch?v=87-omb2tSv8 .
FA info icon.svgAngle down icon.svgPage data
Keywords 3d printing, diffraction, electric lighting, electricity, monochromator, osat, science equipment, plastic
SDG SDG04 Quality education, SDG10 Reduced inequalities
Authors Anthony Rettig
License CC-BY-SA-3.0
Language English (en)
Translations Spanish
Related 1 subpages, 4 pages link here
Impact 953 page views
Created December 4, 2018 by Anthony Rettig
Modified October 23, 2023 by StandardWikitext bot
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