---
title: "Waves & optics — Sandbox Physics"
description: "Follow light through a raindrop, a lens, or an interferometer."
canonical_url: "https://sandboxphysics.com/topics/waves-and-optics/"
language: "en"
page_type: "lab-directory"
alternate_languages:
  zh-CN: "https://sandboxphysics.com/zh/topics/waves-and-optics/"
last_modified: "2026-10-24"
---

[← All Labs](https://sandboxphysics.com/labs/) 02 / 04

Light · Interference · Imaging

# Waves & optics

Follow light through a raindrop, a lens, or an interferometer.

155 experiments

Start here

## From one ray to interference measurement

Start with refraction, find where the ray picture stops working, then use interference to measure tiny distances.

6 Labs · about 72 min

1. [01 Observe Optical Boundary Explorer Turn the incident angle and watch reflected and transmitted power trade off. Then switch to the critical-angle scene. 11 min](https://sandboxphysics.com/labs/optical-boundary-explorer/)
2. [02 Compare Rainbow Caustic Observatory Change the wavelength and follow one drop: why does each colour leave at a slightly different angle? 13 min](https://sandboxphysics.com/labs/rainbow-laboratory/)
3. [03 Model Camera Obscura Shrink the pinhole and move the screen. Find where geometric blur stops shrinking and diffraction takes over. 13 min](https://sandboxphysics.com/labs/camera-obscura/)
4. [04 Model Coherent Wave Composer Set two waves to opposite phase and watch the phasor sum close. Then add more waves. 11 min](https://sandboxphysics.com/labs/coherent-wave-composer/)
5. [05 Compare Young Double-Slit Bench Widen the slits, then separate them, to tell the diffraction envelope from the interference fringes. 11 min](https://sandboxphysics.com/labs/young-double-slit-bench/)
6. [06 Transfer Michelson Precision Lab Move one mirror by less than a micrometre and follow the fringes as they pass. Interference becomes a ruler. 13 min](https://sandboxphysics.com/labs/michelson-precision-lab/)

## Browse the collection

Find an experiment

155 experiments

1. [Waves & optics CMB Spectrum Thermometer How can a small foreground make a precise cosmic thermometer read too warm? 12 min](https://sandboxphysics.com/labs/cmb-spectrum-thermometer/)
2. [Waves & optics CMB Sky and Angular Power Why does a broad telescope beam remove small sky patterns before large ones? 12 min](https://sandboxphysics.com/labs/cmb-sky-angular-spectrum/)
3. [Waves & optics Spontaneous Raman Spectrometer Do molecular lines keep the same energy shift when the laser changes? 18 min](https://sandboxphysics.com/labs/spontaneous-raman-spectrometer/)
4. [Waves & optics Optical Tweezers: Brownian Calibration How does a bead’s thermal motion reveal the stiffness of an optical trap? 18 min](https://sandboxphysics.com/labs/optical-tweezers-calibration/)
5. [Waves & optics Attosecond RABBIT Metrology How can electron spectra reveal the duration of an attosecond pulse train? 20 min](https://sandboxphysics.com/labs/attosecond-rabbitt-metrology/)
6. [Waves & optics Radio Echoes from the Ionosphere Why does a radio echo suggest a higher layer than the height where the wave actually turns? 15 min](https://sandboxphysics.com/labs/ionospheric-radio-sounding/)
7. [Waves & optics Single-Pass Optical Amplifier Why does an inverted medium stop giving exponential gain? 20 min](https://sandboxphysics.com/labs/single-pass-amplifier/)
8. [Waves & optics Passive Optical Resonator How can two mirrors with no gain between them pick out frequencies and store light? 20 min](https://sandboxphysics.com/labs/passive-optical-resonator/)
9. [Waves & optics Gain Curve Meets Longitudinal Modes Which cavity modes survive after they saturate the gain? 25 min](https://sandboxphysics.com/labs/gain-longitudinal-modes/)
10. [Waves & optics Stable Resonator Geometry Does a stable cavity guarantee that its beam fits through the aperture? 25 min](https://sandboxphysics.com/labs/stable-resonator-geometry/)
11. [Waves & optics Alignment & Mode Matching Why can a centered beam still reflect from a resonant cavity? 25 min](https://sandboxphysics.com/labs/alignment-mode-matching/)
12. [Waves & optics Mode Locking Can a laser reach a much higher peak power without any more energy? 25 min](https://sandboxphysics.com/labs/mode-locking-frequency-comb/)
13. [Waves & optics Semiconductor Laser Diode When does injected current become coherent output? 25 min](https://sandboxphysics.com/labs/semiconductor-laser-diode/)
14. [Waves & optics Ti:Sapphire Ultrafast Oscillator What keeps an ultrashort pulse alive after every round trip? 25 min](https://sandboxphysics.com/labs/ti-sapphire-oscillator/)
15. [Waves & optics Raman & Brillouin Lasers Can transparent glass become a laser gain medium? 25 min](https://sandboxphysics.com/labs/raman-brillouin-lasers/)
16. [Waves & optics Random Laser Can scattering hold light long enough to lase? 25 min](https://sandboxphysics.com/labs/random-laser/)
17. [Waves & optics Thermal Lensing & High-Power Scaling Can better cooling alone fix the beam of a high-power laser? 25 min](https://sandboxphysics.com/labs/thermal-lensing/)
18. [Waves & optics External Feedback & Laser Chaos When does a delayed reflection destabilize a laser? 25 min](https://sandboxphysics.com/labs/external-feedback-chaos/)
19. [Waves & optics Tunable Laser & Mode-Hop-Free Scan Why does rotating a grating alone cause mode hops? 25 min](https://sandboxphysics.com/labs/tunable-laser-scan/)
20. [Waves & optics Coherent Beam Combining In coherent beam combining, does locking the phases fix every error? 25 min](https://sandboxphysics.com/labs/coherent-beam-combining/)
21. [Waves & optics Microresonator Kerr Comb When can a laser-driven microring keep a short pulse circling inside it? 25 min](https://sandboxphysics.com/labs/microresonator-kerr-comb/)
22. [Waves & optics Pound–Drever–Hall Frequency Lock Can reflection tell a laser which way to tune? 25 min](https://sandboxphysics.com/labs/pdh-frequency-lock/)
23. [Waves & optics Laser Linewidth & Phase Noise How does phase noise become a laser linewidth? 25 min](https://sandboxphysics.com/labs/laser-linewidth-phase-noise/)
24. [Waves & optics Injection Locking How can a weak master laser make a stronger slave laser follow its frequency? 25 min](https://sandboxphysics.com/labs/injection-locking/)
25. [Waves & optics Regenerative & Multipass Amplifier When should a pulse circulating in a regenerative amplifier be let out? 25 min](https://sandboxphysics.com/labs/regenerative-multipass-amplifier/)
26. [Waves & optics Nonlinear Frequency Conversion Does a longer crystal always make more new light? 25 min](https://sandboxphysics.com/labs/nonlinear-frequency-conversion/)
27. [Waves & optics Chirped Pulse Amplification Can a short pulse be amplified without its peak power getting dangerously high? 25 min](https://sandboxphysics.com/labs/chirped-pulse-amplification/)
28. [Waves & optics Fiber Laser & FBG Cavity Does more fiber always give more useful output? 25 min](https://sandboxphysics.com/labs/fiber-fbg-laser/)
29. [Waves & optics DFB, DBR & VCSEL Architectures Where should feedback sit to select a laser mode? 25 min](https://sandboxphysics.com/labs/laser-feedback-architectures/)
30. [Waves & optics Laser Medium Zoo How do different laser media reach population inversion? 25 min](https://sandboxphysics.com/labs/laser-medium-zoo/)
31. [Waves & optics Optical Frequency Comb What must you measure before a frequency comb can work as a ruler for light? 25 min](https://sandboxphysics.com/labs/optical-frequency-comb/)
32. [Waves & optics Laser Dynamics & Relaxation Oscillation Why does a laser overshoot before it settles? 25 min](https://sandboxphysics.com/labs/laser-dynamics-relaxation/)
33. [Waves & optics Q-Switched Giant Pulse How can stored inversion become a giant pulse? 25 min](https://sandboxphysics.com/labs/q-switched-giant-pulse/)
34. [Waves & optics Output Coupler Optimization Which output mirror gives a laser the most output power? 25 min](https://sandboxphysics.com/labs/output-coupler-optimization/)
35. [Waves & optics Gaussian Beam & Beam Quality Can a lens make a poor beam diffraction limited? 25 min](https://sandboxphysics.com/labs/gaussian-beam-quality/)
36. [Waves & optics Transverse Laser Modes Which beam pattern wins when a laser's transverse modes compete for gain? 25 min](https://sandboxphysics.com/labs/transverse-laser-modes/)
37. [Waves & optics Build & Debug Your First Laser When a laser you built won't lase, how do you find the fault? 25 min](https://sandboxphysics.com/labs/build-debug-laser/)
38. [Waves & optics Laser Diagnostic Bench Which measurements tell laser light apart from fluorescence and amplified spontaneous emission? 25 min](https://sandboxphysics.com/labs/laser-diagnostic-bench/)
39. [Waves & optics Laser Noise Startup Workbench Where does the first photon in a laser cavity come from? 20 min](https://sandboxphysics.com/labs/laser-noise-startup/)
40. [Waves & optics Population Inversion Workbench Why can stronger pumping still fail to produce gain? 15 min](https://sandboxphysics.com/labs/population-inversion/)
41. [Waves & optics Three Light–Matter Transitions Does stimulated emission always mean amplification? 15 min](https://sandboxphysics.com/labs/light-matter-transitions/)
42. [Waves & optics Laser vs Lamp vs LED Can a very bright light still make interference fringes with poor contrast? 15 min](https://sandboxphysics.com/labs/laser-source-comparison/)
43. [Waves & optics When Two Waves Meet Why do passing waves leave a stable fringe pattern? 6 min](https://sandboxphysics.com/labs/wave-interference/)
44. [Waves & optics Draw Any Wave with Circles How can steady rotations rebuild almost any periodic signal? 12 min](https://sandboxphysics.com/labs/fourier-epicycles/)
45. [Waves & optics Light after a Narrow Slit Why does a narrower opening spread light farther? 8 min](https://sandboxphysics.com/labs/diffraction/)
46. [Waves & optics How a Lens Redirects Light How do three principal rays locate and size an image? 7 min](https://sandboxphysics.com/labs/lens-optics/)
47. [Waves & optics Listen to Spacetime with Light How can a length change smaller than a proton become a readable signal? 15 min](https://sandboxphysics.com/labs/ligo-interferometer/)
48. [Waves & optics How One Opening Redraws a Water Wave Why does narrowing an opening spread the transmitted wave through a wider angle? 9 min](https://sandboxphysics.com/labs/ripple-tank/)
49. [Waves & optics Two Refractions inside a Thick Lens What does the thin-lens model miss when thickness matters? 12 min](https://sandboxphysics.com/labs/thick-lens-refraction/)
50. [Waves & optics A Rainbow Only Nanometres Thick Why does a colorless film only hundreds of nanometres thick develop flowing color? 11 min](https://sandboxphysics.com/labs/thin-film-interference/)
51. [Waves & optics How a Laser Builds inside a Cavity Which waves return between two mirrors and keep growing? 15 min](https://sandboxphysics.com/labs/laser-resonant-cavity/)
52. [Waves & optics Optical Boundary Explorer What happens to light's speed, direction and power when it crosses into a new material? 11 min](https://sandboxphysics.com/labs/optical-boundary-explorer/)
53. [Waves & optics Hall of Mirrors Which virtual images can an observer actually see as mirrors move? 11 min](https://sandboxphysics.com/labs/hall-of-mirrors/)
54. [Waves & optics Mirror Engineering Challenge Can a few mirrors steer a beam to a fixed target just by getting the angles right? 13 min](https://sandboxphysics.com/labs/mirror-engineering-challenge/)
55. [Waves & optics Curved Mirror Observatory How does mirror shape move the focus and change off-axis image quality? 13 min](https://sandboxphysics.com/labs/curved-mirror-observatory/)
56. [Waves & optics Caustic Factory Why does light reflected or refracted by a curved surface gather into sharp, bright curves? 15 min](https://sandboxphysics.com/labs/caustic-factory/)
57. [Waves & optics Floating Image Mirascope Where do two facing parabolic mirrors form the floating image you can see but not touch? 15 min](https://sandboxphysics.com/labs/floating-image-mirascope/)
58. [Waves & optics Fermat Path Finder Why can one rule about travel time explain reflection, refraction and curved light rays? 13 min](https://sandboxphysics.com/labs/fermat-path-finder/)
59. [Waves & optics Underwater Vision Observatory How can one flat water surface make a fish look shallower, fool a spear, squeeze the sky and distort photos? 11 min](https://sandboxphysics.com/labs/underwater-vision/)
60. [Waves & optics Window Ghost Observatory Why does window glass barely shift the view through it, yet show ghost images at night? 11 min](https://sandboxphysics.com/labs/window-glass-slab-lab/)
61. [Waves & optics N-BK7 Prism Spectrometer Observatory How do you set up a glass prism so that where each color lands tells you its wavelength? 13 min](https://sandboxphysics.com/labs/build-a-prism-spectrometer/)
62. [Waves & optics Rainbow Caustic Observatory How can one water drop create primary and secondary bows with a dark band between them? 13 min](https://sandboxphysics.com/labs/rainbow-laboratory/)
63. [Waves & optics Mirage & Green-Flash Observatory How can layers of warm and cool air make distant objects sink, rise or appear several times? 15 min](https://sandboxphysics.com/labs/atmospheric-refraction-theatre/)
64. [Waves & optics GRIN Geometry Observatory How can a smoothly varying refractive index guide and focus light with no surfaces inside it? 15 min](https://sandboxphysics.com/labs/gradient-index-worlds/)
65. [Waves & optics Eclipse & Transit Shadow Observatory How do the sizes of a light source and of the body blocking it shape shadows, eclipses and transits? 13 min](https://sandboxphysics.com/labs/shadow-eclipse-lab/)
66. [Waves & optics Unilluminable Room Can a room with mirrored walls have a spot that a single small lamp inside never lights? 15 min](https://sandboxphysics.com/labs/unilluminable-room/)
67. [Waves & optics Solar Concentrator & Étendue Why can't any lens or mirror concentrate sunlight onto an arbitrarily small spot? 15 min](https://sandboxphysics.com/labs/solar-concentrator-etendue/)
68. [Waves & optics Illumination & Radiometry Studio How do you light a flat surface evenly when light fades with distance and angle? 13 min](https://sandboxphysics.com/labs/illumination-radiometry-studio/)
69. [Waves & optics Ray Cloaking Challenge Can a set of lenses steer light around an object and leave the background looking unchanged? 15 min](https://sandboxphysics.com/labs/ray-cloaking-challenge/)
70. [Waves & optics Branched Light in Random Media Why does light crossing gently uneven material gather into branches instead of spreading evenly? 15 min](https://sandboxphysics.com/labs/branched-light-in-random-media/)
71. [Waves & optics Gravitational Lens Telescope How can light bent around an unseen mass reveal how heavy it is? 17 min](https://sandboxphysics.com/labs/gravitational-lens-telescope/)
72. [Waves & optics Thin Lens Imaging Bench How do three principal rays locate every real and virtual thin-lens image? 11 min](https://sandboxphysics.com/labs/thin-lens-imaging-bench/)
73. [Waves & optics Thick Lens Designer What does the thin-lens approximation miss for a lens with real thickness? 17 min](https://sandboxphysics.com/labs/thick-lens-designer/)
74. [Waves & optics Compound Optics Workbench How can one matrix tell you where a chain of lenses forms its image and how much it magnifies? 17 min](https://sandboxphysics.com/labs/compound-optics-workbench/)
75. [Waves & optics Parfocal Zoom Challenge Can moving lens groups change focal length while the image plane stays fixed? 17 min](https://sandboxphysics.com/labs/parfocal-zoom-challenge/)
76. [Waves & optics Camera Obscura What size of pinhole gives the sharpest picture? 13 min](https://sandboxphysics.com/labs/camera-obscura/)
77. [Waves & optics Photography Optics Playground From one camera position, what do focal length and aperture change in a photo? 13 min](https://sandboxphysics.com/labs/photography-optics-playground/)
78. [Waves & optics Lens Aberration Clinic How do you identify a lens aberration from its blur and fix it without creating another? 17 min](https://sandboxphysics.com/labs/lens-aberration-clinic/)
79. [Waves & optics Anamorphic & Cylindrical Optics How can a lens stretch or squeeze an image in one direction only? 15 min](https://sandboxphysics.com/labs/anamorphic-cylindrical-optics/)
80. [Waves & optics Human Eye & Corrective Optics What lens corrects short sight, long sight, presbyopia or astigmatism? 13 min](https://sandboxphysics.com/labs/human-eye-corrective-optics/)
81. [Waves & optics Build a Microscope What sets the smallest detail a microscope can resolve? 13 min](https://sandboxphysics.com/labs/build-a-microscope/)
82. [Waves & optics Build a Telescope How do aperture, optical layout, and obstruction determine what a telescope can resolve? 13 min](https://sandboxphysics.com/labs/build-a-telescope/)
83. [Waves & optics Binocular Prism Lab How do binocular prisms turn the image upright, and why can a roof prism blur it? 17 min](https://sandboxphysics.com/labs/binocular-prism-lab/)
84. [Waves & optics Telecentric Metrology Camera Can a camera measure an object's size correctly when the image is out of focus? 15 min](https://sandboxphysics.com/labs/telecentric-metrology-camera/)
85. [Waves & optics Tilt-Shift & Scheimpflug Studio How does tilting the lens rotate the plane of focus and reshape depth of field? 15 min](https://sandboxphysics.com/labs/tilt-shift-scheimpflug-studio/)
86. [Waves & optics Pupils, Stops & Vignetting What do the different openings inside a lens system each limit? 17 min](https://sandboxphysics.com/labs/pupils-stops-vignetting/)
87. [Waves & optics Projector Optics Lab Why can a bigger light source fail to brighten a projector, and why does a tilted screen also blur? 17 min](https://sandboxphysics.com/labs/projector-optics-lab/)
88. [Waves & optics Smartphone Camera Module What do folding, autofocus and stabilization each do in a thin phone camera, and what can none of them fix? 17 min](https://sandboxphysics.com/labs/smartphone-camera-module/)
89. [Waves & optics VR Headset Optics Why can a VR headset change depth while focus stays fixed, and why does a small eye shift cut off the corners? 15 min](https://sandboxphysics.com/labs/vr-headset-optics/)
90. [Waves & optics Ghost Image, Pepper’s Ghost & HUD Where does a half-mirror image appear, and why can a bright background or the mirror’s edge hide it? 13 min](https://sandboxphysics.com/labs/ghost-image-peppers-ghost-hud/)
91. [Waves & optics Light-Field Camera & Display Can one light-field photo be focused on either near or far objects, and what does that cost? 15 min](https://sandboxphysics.com/labs/light-field-camera-display/)
92. [Waves & optics Coherent Wave Composer Why do a phasor diagram, a wavefront picture and a detector reading all describe the same interference? 11 min](https://sandboxphysics.com/labs/coherent-wave-composer/)
93. [Waves & optics Young Double-Slit Bench How do slit width, slit spacing, phase and coherence each change a double-slit pattern? 11 min](https://sandboxphysics.com/labs/young-double-slit-bench/)
94. [Waves & optics Thin-Film Color Studio Why does a thin film reflect color, and why does the color shift when you tilt it? 13 min](https://sandboxphysics.com/labs/thin-film-color-studio/)
95. [Waves & optics Interference Surface Metrology How can interference fringes map the shape of a surface, down to tiny defects? 13 min](https://sandboxphysics.com/labs/interference-surface-metrology/)
96. [Waves & optics Michelson Precision Lab How can counting fringes measure displacement, wavelength, and refractive index? 13 min](https://sandboxphysics.com/labs/michelson-precision-lab/)
97. [Waves & optics LIGO Interferometer How does a kilometer-long interferometer turn a passing gravitational wave into a measurable signal? 17 min](https://sandboxphysics.com/labs/ligo-system-interferometer/)
98. [Waves & optics Mach–Zehnder Sensor Can a Mach–Zehnder’s two outputs tell a refractive-index change from absorption or polarization marking? 17 min](https://sandboxphysics.com/labs/mach-zehnder-sensor/)
99. [Waves & optics Fabry–Pérot Passive Cavity How can two highly reflective mirrors let all the light through, and what does loss do to the resonance? 17 min](https://sandboxphysics.com/labs/fabry-perot-passive-cavity/)
100. [Waves & optics Sagnac Gyroscope How can two beams in the same fiber detect rotation, and why can’t brightness alone tell which way it turns? 17 min](https://sandboxphysics.com/labs/sagnac-gyroscope/)
101. [Waves & optics Division-of-Wavefront Interferometers Why is the fringe dark where Lloyd’s mirror meets the screen, but bright at a biprism’s center? 17 min](https://sandboxphysics.com/labs/division-of-wavefront-interferometers/)
102. [Waves & optics Low-Coherence Interferometry & OCT How can broadband light reveal the depth a reflection came from inside a sample? 15 min](https://sandboxphysics.com/labs/low-coherence-interferometry-oct/)
103. [Waves & optics Stellar Interferometer How can two telescopes measure a star too small for either one to resolve? 15 min](https://sandboxphysics.com/labs/stellar-interferometer/)
104. [Waves & optics Speckle Lab Why does coherent light scattered by a diffuser look grainy, and can averaging images smooth it out? 15 min](https://sandboxphysics.com/labs/speckle-lab/)
105. [Waves & optics Holography Studio How can a plate that records only brightness keep the phase needed to rebuild a three-dimensional wavefront? 17 min](https://sandboxphysics.com/labs/holography-studio/)
106. [Waves & optics Moiré & Fringe Metrology How can broad fringe patterns reveal a tiny shift or the shape of a surface? 15 min](https://sandboxphysics.com/labs/moire-fringe-metrology/)
107. [Waves & optics Huygens–Fresnel Propagation Lab How does a diffraction pattern change from close to the aperture to far away? 13 min](https://sandboxphysics.com/labs/huygens-fresnel-propagation-lab/)
108. [Waves & optics Aperture Diffraction Studio How is the diffraction from a hole related to that from an obstacle of the same shape? 13 min](https://sandboxphysics.com/labs/aperture-diffraction-studio/)
109. [Waves & optics Crystal Diffraction & Reciprocal Space How can the spots and rings in a diffraction pattern reveal a crystal’s lattice? 17 min](https://sandboxphysics.com/labs/crystal-diffraction-reciprocal-space/)
110. [Waves & optics Diffraction-Grating Spectrometer What sets how finely a grating spectrometer can separate two close wavelengths? 13 min](https://sandboxphysics.com/labs/diffraction-grating-spectrometer/)
111. [Waves & optics Diffractive Lens Workshop How does a diffractive lens focus light, and what do finer phase steps improve? 17 min](https://sandboxphysics.com/labs/diffractive-lens-workshop/)
112. [Waves & optics Talbot Carpet Why does light behind a grating repeat the grating’s pattern at certain distances? 15 min](https://sandboxphysics.com/labs/talbot-carpet/)
113. [Waves & optics Optical Fourier Processor How can a mask between two lenses keep only an image’s edges, blur it or erase a repeating pattern? 17 min](https://sandboxphysics.com/labs/optical-fourier-processor/)
114. [Waves & optics Abbe Resolution Lab Why can tilting the light reveal stripes a microscope misses, and why can blocking some light fake finer ones? 13 min](https://sandboxphysics.com/labs/abbe-resolution-lab/)
115. [Waves & optics PSF–OTF–MTF Imaging Lab Can a lens swap the bright and dark parts of stripes, and can pixels invent a stripe period that isn’t there? 17 min](https://sandboxphysics.com/labs/psf-otf-mtf-imaging-lab/)
116. [Waves & optics Phase Microscopy Lab Can a transparent cell be seen without staining, and is the relief it seems to have real? 15 min](https://sandboxphysics.com/labs/phase-microscopy-lab/)
117. [Waves & optics Schlieren Flow Viewer How does a knife edge make invisible air flow visible, and why does turning it make some features vanish? 15 min](https://sandboxphysics.com/labs/schlieren-flow-viewer/)
118. [Waves & optics Pupil Engineering & Coronagraph How can a telescope block a star’s light and still see a planet right next to it? 15 min](https://sandboxphysics.com/labs/pupil-engineering-coronagraph/)
119. [Waves & optics Phase Retrieval Challenge Can you recover the phase of light from brightness measurements alone? 15 min](https://sandboxphysics.com/labs/phase-retrieval-challenge/)
120. [Waves & optics Coded-Aperture Camera How can a camera with a patterned mask instead of a lens form an image? 15 min](https://sandboxphysics.com/labs/coded-aperture-camera/)
121. [Waves & optics Computational Deblurring Lab When does deconvolution recover detail, and when does it only amplify noise or model error? 17 min](https://sandboxphysics.com/labs/computational-deblurring-lab/)
122. [Waves & optics Adaptive Optics Observatory How can measured wavefront slopes drive a mirror fast enough to sharpen a turbulent star image? 15 min](https://sandboxphysics.com/labs/adaptive-optics-observatory/)
123. [Waves & optics Ptychography & Coherent Diffraction Imaging How can overlapping illumination recover both the amplitude and the phase of an object without a lens? 15 min](https://sandboxphysics.com/labs/ptychography-coherent-diffraction-imaging/)
124. [Waves & optics Polarization State Explorer How can a Jones vector, an ellipse and Stokes measurements all describe the same polarization state? 13 min](https://sandboxphysics.com/labs/polarization-state-explorer/)
125. [Waves & optics Polarized Reflections & Sky Why does a polarizing filter usually need different angles to darken water glare and blue sky? 13 min](https://sandboxphysics.com/labs/polarized-reflections-sky/)
126. [Waves & optics Birefringent Crystal Lab Why does a birefringent crystal split one ray into two side-by-side rays? 13 min](https://sandboxphysics.com/labs/birefringent-crystal-lab/)
127. [Waves & optics Waveplate & Poincaré Sphere Lab How does a waveplate move a polarization state on the Poincaré sphere? 13 min](https://sandboxphysics.com/labs/waveplate-poincare-sphere-lab/)
128. [Waves & optics Optical Activity Polarimeter What can a rotating analyzer really tell us about an unknown chiral solution? 13 min](https://sandboxphysics.com/labs/optical-activity-polarimeter/)
129. [Waves & optics Photoelastic Stress Viewer How do colorful polarization fringes map the principal-stress difference inside a loaded object? 15 min](https://sandboxphysics.com/labs/photoelastic-stress-viewer/)
130. [Waves & optics LCD Pixel Microscope How can three voltage-controlled liquid-crystal shutters make one colored pixel? 17 min](https://sandboxphysics.com/labs/lcd-pixel-microscope/)
131. [Waves & optics TIR Phase & Fresnel Rhomb How can total internal reflection, which returns all the light, act as a waveplate that works across many wavelengths? 15 min](https://sandboxphysics.com/labs/tir-phase-fresnel-rhomb/)
132. [Waves & optics Faraday Isolator Why can a Faraday isolator pass light going forward but block the same light coming back? 17 min](https://sandboxphysics.com/labs/faraday-isolator/)
133. [Waves & optics Electro-Optic Modulator How can a voltage across a crystal control the brightness of a light beam? 17 min](https://sandboxphysics.com/labs/electro-optic-modulator/)
134. [Waves & optics Optical Fiber: Rays to Modes When does the picture of rays bouncing inside a fiber stop working, so that light must be treated as modes? 13 min](https://sandboxphysics.com/labs/optical-fiber-rays-to-modes/)
135. [Waves & optics Fiber Pulse Propagation How does dispersion reshape an ultrashort pulse as it travels along a fiber? 17 min](https://sandboxphysics.com/labs/fiber-pulse-propagation/)
136. [Waves & optics Evanescent Directional Coupler How can light cross from one waveguide into a nearby one that it never touches? 15 min](https://sandboxphysics.com/labs/evanescent-directional-coupler/)
137. [Waves & optics Microring & Whispering-Gallery Resonator Why does a small ring beside a waveguide make the transmitted light dip at certain wavelengths? 15 min](https://sandboxphysics.com/labs/microring-whispering-gallery-resonator/)
138. [Waves & optics Photonic Crystal Band Structure How can a periodic dielectric block some frequencies of light, yet trap or guide light at defects? 15 min](https://sandboxphysics.com/labs/photonic-crystal-band-structure/)
139. [Waves & optics Boundary Wave Tunnel How can light still get through a narrow gap when it should be totally internally reflected? 15 min](https://sandboxphysics.com/labs/boundary-wave-tunnel/)
140. [Waves & optics Beam Shift Microscope Why does a reflected light beam shift slightly, both within and out of the plane of incidence? 15 min](https://sandboxphysics.com/labs/beam-shift-microscope/)
141. [Waves & optics Gaussian Beam & Gouy Phase How do the width and phase of a focused Gaussian beam change as it passes through the focus? 17 min](https://sandboxphysics.com/labs/gaussian-beam-gouy-phase/)
142. [Waves & optics Self-Healing Beam Arena How do Bessel and Airy beams rebuild themselves after part of them is blocked? 15 min](https://sandboxphysics.com/labs/self-healing-beam-arena/)
143. [Waves & optics Light in Disorder How can interference in disordered material send extra light straight back, or stop light from spreading sideways? 15 min](https://sandboxphysics.com/labs/light-in-disorder/)
144. [Waves & optics Optical Vortex & OAM Can a bright petal pattern carry zero average orbital angular momentum? 15 min](https://sandboxphysics.com/labs/optical-vortex-oam/)
145. [Waves & optics Vector Beams & Optical Skyrmions What makes the polarization pattern across a beam an optical skyrmion? 15 min](https://sandboxphysics.com/labs/vector-beams-optical-skyrmions/)
146. [Waves & optics Photonic Nanojet & Hook How can a tiny transparent particle squeeze light into a very narrow jet, or bend it into a hook? 15 min](https://sandboxphysics.com/labs/photonic-nanojet-hook/)
147. [Waves & optics Superoscillation Designer How can band-limited waves add up to a hotspot smaller than the diffraction limit? 15 min](https://sandboxphysics.com/labs/superoscillation-designer/)
148. [Waves & optics Surface Plasmon Resonance Lab How does surface plasmon resonance detect a change in a sample's refractive index? 15 min](https://sandboxphysics.com/labs/surface-plasmon-resonance-lab/)
149. [Waves & optics Negative Refraction & Superlens How does a negative-index slab bend light the wrong way and recover fine detail that normally fades out? 15 min](https://sandboxphysics.com/labs/negative-refraction-superlens/)
150. [Waves & optics Topological Photonic Edge State Why is a topological edge mode so hard for defects to remove? 15 min](https://sandboxphysics.com/labs/topological-photonic-edge-state/)
151. [Waves & optics Nonlinear Light Shapes Its Own Medium When can a bright beam change a material's refractive index enough to focus itself and stop spreading? 15 min](https://sandboxphysics.com/labs/nonlinear-light-shapes-its-own-medium/)
152. [Waves & optics Absorption, Spontaneous & Stimulated Emission What decides whether atoms absorb resonant light or amplify it? 13 min](https://sandboxphysics.com/labs/absorption-spontaneous-stimulated-emission/)
153. [Waves & optics Pumping & Population Inversion Why can't pumping a two-level system produce population inversion, when three- and four-level schemes can? 13 min](https://sandboxphysics.com/labs/pumping-population-inversion/)
154. [Waves & optics Laser Startup from Noise How does a laser grow from random noise into one dominant mode? 17 min](https://sandboxphysics.com/labs/laser-startup-from-noise/)
155. [Waves & optics Stable Resonator & Transverse Modes How should two mirrors be curved and spaced to make a stable cavity that favors the fundamental mode? 17 min](https://sandboxphysics.com/labs/stable-resonator-transverse-modes/)

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