geoptics-thin-lens

Gaussian thin-lens optics in a few lines of CommonJS. No dependencies.

Handles the ideal thin-lens model: a single lens with negligible thickness, paraxial rays. That covers the vast majority of intro-optics problems and quick imaging estimates. Thick lenses, aberrations and ray tracing are out of scope.

Sign convention

Cartesian, as used in most introductory texts:

• object distance do positive for a real object,
• image distance di positive → real image on the far side,
• converging lens has f > 0, diverging f < 0,
• magnification m negative → inverted image.

Usage

const optics = require('geoptics-thin-lens');

const di = optics.imageDistance(10, 15);      // 30
const m  = optics.magnification(15, di);      // -2  (inverted, 2x)
optics.isReal(di);                            // true

Lensmaker's equation for a lens in air:

// n = 1.5, biconvex, R1 = +0.1 m, R2 = -0.1 m
optics.lensmaker(1.5, 0.1, -0.1);            // f = 0.1 m
optics.powerDioptres(0.1);                    // 10 D

Functions

• imageDistance(f, do)
• magnification(do, di)
• imageHeight(ho, m)
• combinedFocalLength(f1, f2) — two thin lenses in contact
• lensmaker(n, R1, R2)
• powerDioptres(fMetres)
• isReal(di)

License

ISC