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Optics

The Most Precise Ruler in the Universe

Start with the video, then use the science notes and recommended parts below to follow the idea behind the build.

Optics

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How it works

What this project is testing.

An interferometer is a ruler made out of phase. It splits light into two paths, brings the paths back together, and lets bright and dark fringes reveal tiny changes in distance.

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This project builds a Michelson interferometer, the same basic idea behind some of the most important measurements in modern physics. If one path changes by a fraction of a wavelength, the interference pattern moves.

Δ ϕ = \frac{2 π}{λ} Δ L

Changing optical path length changes the phase between the two beams.

2Δ x = N λ

Mirror motion is doubled by the round trip, so fringe counts become a distance measurement.

Recommended parts

Products used in this project.

Affiliate links may earn Keystone Science a commission. Match ratings, values, sizes, polarity, and safety requirements to your own build before buying.

Rigol Digital Oscilloscope DS1054Z 50 MHz 4-Ch 1 GSa/s 24 Mpts 30,000 wfms/s UltraVision 7" 800x480 Intensity Display, 60,000-Frame Record/Playback, Serial Decode UART I2C SPI for Debug & Education

oscilloscopetest equipment

Rigol DS1054Z Digital Oscilloscope, 50 MHz, 4 Channel, 1 GSa/s

$349.004.7(724)

Good bench choice; budget scope alternatives may be cheaper but less durable.

Syncwire 3.5mm Nylon Braided Aux Cable (3.3ft/1m,Hi-Fi Sound), Audio Auxiliary Input Adapter Male to Male Cord for Headphones, Car, Home Stereos, Speaker, iPhone, iPad, iPod, Echo & More – Black

audio source / phoneaudio

3.5mm Nylon Braided Aux Cable, Male to Male, 3.3ft

$7.994.6(119K)

Use with an existing phone or audio player.

WOWOONE Laser Diode 30Pcs 5V 650nm 5mW Mini Red Dot Laser Head, 6mm Outer Diameter Laser Module with Leads, for Arduino Laser DIY Electronics Projects, High-Stability Red Laser Diode

laser / laser pointeroptics

30pcs 5V 650nm 5mW Mini Red Dot Laser Diode Modules with Leads

$12.994.6(152)

Laser safety matters. Keep recommendations to low-power modules and add eye-safety warnings. Review requirements and safety guidance before buying.

RUEHALF Front Surface Mirrors, 100 * 100 * 3mm First 1st Surface Mirror,Surface Mirror Optics Quality for Engineering and Scientific Project

mirroroptics

Front Surface Mirror, 100 x 100 x 3mm, First Surface Optics Quality Mirror

$19.04

For interferometer/optics use, prefer first-surface mirrors over bathroom/craft mirrors. Amazon review evidence is sparse. Review requirements and safety guidance before buying.

Optical Glass Cube Dichroic Beam Splitter Prism Ratio 50:50 Spectrome Sicence 15X15X15MM

beam splitteroptics

Optical Glass Cube Dichroic Beam Splitter Prism, 50:50, 15x15x15mm

$13.994.8(17)

Specialty optics have fewer Amazon reviews; verify size and wavelength before publishing. Review requirements and safety guidance before buying.

$Physics Optical Experiment Set Multifunction Reflector Refraction Triangular Prism Convex Lens Concave Mirror Dial Linear Light Source Teaching Demonstration Equipment for Teacher Student Education$

lensoptics

Physics Optical Experiment Set with Prism, Convex Lens, Concave Mirror, and Linear Light Source

$18.994.3(198)

Specialty optics may need size and focal-length review before publishing.

Logitech HD Pro Webcam C920, Widescreen Video Calling and Recording, 1080p Camera, Desktop or Laptop Webcam

camerarecording/measurement

Logitech HD Pro Webcam C920, 1080p Widescreen Video Calling and Recording

$68.474.6(33K)

Project files

Prints, kits, and downloads.

Diagrams, printable files, kits, or companion downloads will appear here when they are ready to use.

Coming soon

Contact

Events, speaking, collaborations, and news.

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