Lens, mirror, refraction, diffraction, and light intensity calculators. Browse our free optics tools below — all calculators are instant, accurate, and require no sign-up.
Angle of Incidence Calculator — Calculate the angle of incidence using Snell's Law given refractive indices and angle of refraction. Includes Fresnel reflectance and Brewster angle.
Angle of Refraction Calculator — Calculate the angle of refraction using Snell's Law. Includes critical angle, Brewster angle, Fresnel reflectance, and a multi-angle comparison table.
Angular Resolution Calculator — Calculate angular resolution using the Rayleigh criterion, Dawes' limit, and Sparrow limit. Compare apertures and find minimum resolvable features.
Aperture Area Calculator — Calculate the area of circular apertures for telescopes, cameras, and optical systems. Compare f-stops, central obstruction, and light gathering power.
Brewster Angle Calculator — Calculate Brewster's angle for any two media. Includes polarization reflectance, angle comparison tables, and material reference data.
Contact Lens Vertex Distance Calculator — Convert spectacle prescription to contact lens power using vertex distance compensation. Handles sphere, cylinder, and rounding to 0.25 D steps.
Diffraction Calculator — Calculate diffraction patterns for single slit, double slit, diffraction grating, and circular aperture. Includes angle, fringe spacing, and order tables.
Hair Diffraction Calculator — Measure hair diameter using laser diffraction (Babinet's principle). Calculate fringe positions, pattern width, and classify hair type from diffraction data.
Index of Refraction Calculator — Calculate the refractive index from speed of light or Snell's Law angles. Includes material comparison, Brewster angle, critical angle, and wavelength data.
Laser Beam Divergence Calculator — Calculate laser beam divergence, spot size at distance, Rayleigh range, and far-field onset. Supports M² beam quality factor and distance tables.
Laser Beam Expander Calculator — Design Galilean and Keplerian beam expanders. Calculate output beam size, divergence reduction, lens focal lengths, and Rayleigh range improvement.
Laser Brightness Calculator — Calculate laser radiance (brightness), spectral radiance, intensity, beam parameter product, and M² factor. Supports CW and pulsed modes.
Laser Linewidth Calculator — Convert laser linewidth between frequency, wavelength, and wavenumber. Calculate coherence length, coherence time, quality factor, and cavity modes.
Laser Spot Size Calculator — Calculate focused laser spot size, depth of focus, intensity, and power density. Compare focal lengths and evaluate cutting/welding parameters.
Lensmaker's Equation Calculator — Use the lensmaker's equation to find focal length, optical power, and image distance from lens curvature, refractive index, and thickness.
Lumen Calculator — Convert between lumens, candela, lux, and foot-candles. Calculate luminous efficacy, illuminance at distance, and compare light sources.
Lux to Foot-Candle Calculator — Convert between lux and foot-candles. Calculate total lumens for an area, luminous exitance, and compare illuminance levels for different environments.
Mirror Equation Calculator — Calculate image distance, magnification, and image properties for concave and convex mirrors using the mirror equation 1/f = 1/d_o + 1/d_i.
Snell's Law Calculator — Apply Snell's law to find refraction angle, critical angle, Brewster's angle, and Fresnel reflectance at any optical interface.
Telescope Magnification Calculator — Calculate telescope magnification, exit pupil, true field of view, resolution limits, and light gathering power. Compare eyepieces and Barlow lenses.
Thin Lens Equation Calculator — Solve the thin lens equation 1/f = 1/d_o + 1/d_i for image distance, magnification, and image characteristics. Supports converging and diverging lenses.