Wave Optics

Understanding wave properties of light, interference, and diffraction

Topics

How do holograms work?

Holograms work by recording interference patterns between light from an object and a reference beam. When illuminated, these patterns diffract light to recreate the original light field, creating a 3D image that appears to have depth and can be viewed from different angles.

How do lasers work?

Lasers work by stimulating atoms to emit light in phase, creating coherent light where all waves are synchronized. A laser uses an active medium (like a crystal or gas), energy source to excite atoms, and mirrors to amplify and direct the light into a focused beam.

How does a CD work?

CDs work by storing digital data as microscopic pits and lands on a reflective surface. A laser reads the data by reflecting off these pits and lands, with the reflected light creating interference patterns that encode binary information (0s and 1s) representing audio, video, or computer data.

What is a diffraction grating?

A diffraction grating is an optical component with many closely spaced parallel lines or grooves that diffract light into its component wavelengths. It separates white light into a spectrum of colors by causing different wavelengths to diffract at different angles, creating a rainbow pattern.

What is constructive interference?

Constructive interference occurs when two or more waves meet and combine to create a wave with greater amplitude. When wave crests align with crests (or troughs with troughs), they add together, creating a stronger combined wave. This happens when waves are in phase.

What is destructive interference?

Destructive interference occurs when two or more waves meet and cancel each other out, creating a wave with smaller or zero amplitude. When wave crests align with troughs, they subtract from each other, reducing or eliminating the combined wave. This happens when waves are out of phase.

What is diffraction?

Diffraction is the bending and spreading of waves around obstacles or through openings. When waves encounter an obstacle or opening comparable in size to their wavelength, they bend around it and spread out, creating diffraction patterns.

What is interference?

Interference occurs when two or more waves overlap and combine. Constructive interference happens when waves align (peaks with peaks), creating larger waves, while destructive interference happens when waves cancel (peaks with troughs), creating smaller or zero waves.

What is polarization?

Polarization is the orientation of light's electric field oscillations. Unpolarized light oscillates in all directions, while polarized light oscillates in a specific direction. Polarizers filter light to allow only specific orientations to pass.

Why do we see colors in oil slicks?

We see colors in oil slicks due to thin-film interference. Light reflects from both the top and bottom surfaces of the thin oil film, and these reflected waves interfere. Different wavelengths interfere constructively or destructively depending on film thickness, creating colorful patterns as some colors are enhanced while others are canceled.