Holography records both amplitude and phase of light scattered from an object by letting it interfere with a coherent reference beam on a photosensitive plate. The exposure maps the intensity |E_ref + E_obj|², producing fine interference fringes that act as a diffraction grating with spatially varying spacing and orientation. When the plate is later illuminated (often by the reference beam again), diffraction reconstructs the object wavefront so the viewer perceives a three-dimensional image. This simulator renders a simplified 2D scalar fringe pattern from a plane reference wave and a point-like spherical phase center, letting you change wavelength, reference angle, and object lateral offset. It does not simulate the diffraction step, emulsion nonlinearities, or volume hologram Bragg selectivity; those belong to advanced treatments.
Who it's for: Students learning that interference can store phase information, bridging Young’s experiment to modern holographic displays and data storage.
Key terms
Holography
Interference
Reference beam
Object beam
Fringe pattern
Coherence
Diffraction reconstruction
Phase recording
How it works
Holography stores both amplitude and phase by interfering a coherent reference wave with light scattered from the object; the plate records a microscopic fringe pattern that diffracts readout light into the original wavefronts.
Frequently asked questions
Why is a laser usually required?
Fringe spacing is on the order of wavelengths. Thermal or LED sources have short coherence lengths, so fringes wash out over the recording area. Lasers provide the long coherence needed for macroscopic stable patterns.
What does the simulator’s fringe pattern represent?
It is a toy 2D map proportional to cos(φ_ref − φ_obj), where φ_ref is the reference phase and φ_obj mimics a spherical wave from a point. Real objects produce richer phase maps, but the idea—encoding phase in fringe spacing and tilt—is the same.
Are thick holograms the same as thin ones?
No. Thick (volume) holograms obey Bragg selectivity: only certain angles and wavelengths reconstruct efficiently. This page models only the recording interference concept, not Bragg diffraction.
Can holography work with digital sensors?
Yes. Digital holography captures interference on a camera and reconstructs numerically. The underlying need for stable interference between reference and object fields remains.