Optics & Photonics Calculators
Lens equations, diffraction limits, and beam divergence.
- IR Seeker Detection Range (NEP)Noise-limited detection range for a point IR target from radiant intensity, aperture, and detector NEP.R = √( J · τ_atm · τ_opt · A_o / (SNR · NEP) ) A_o = π·D²/4 NEP = √(A_d·Δf)/D*
- Laser NOHD (Nominal Ocular Hazard Distance)Eye-safety standoff range for a CW laser from output power, beam divergence, and exit aperture — the ANSI Z136.1 range-safety number.NOHD = [ √( 4·P / (π·MPE) ) − a ] / θ (P in W, MPE in W/m², a in m, θ full-angle in rad)
- Blackbody Radiance (Planck's Law)Spectral radiance, photon flux, Wien peak, and total exitance of a greybody target — the front end of every EO-IR link budget.L(λ) = ε · (2hc²/λ⁵) · 1/(e^(hc/λkT) − 1) M_tot = ε·σ·T⁴ λ_peak·T = 2897.77 µm·K
- Dawes Angular ResolutionSmallest resolvable double-star separation for a given aperture — the empirical bench limit for an optic.R(arcsec) = 116 / D(mm) = 4.56 / D(in) , compare Rayleigh θ = 1.22·λ/D
- Thin-Lens Equation + MagnificationFind image distance and magnification from focal length and object distance for a single thin lens.1/f = 1/sₒ + 1/sᵢ m = −sᵢ/sₒ
- Airy Disk Diffraction RadiusDiffraction-limited spot size and angular resolution for a circular aperture.θ = 1.22 · λ / D , r_Airy = 1.22 · λ · f / D = 1.22 · λ · N
- Numerical Aperture ⇄ f/#Convert between numerical aperture, f-number, and half-cone angle for a lens or fiber.NA = n · sinθ , f/# = 1 / (2 · NA)
- LED Junction TemperatureEstimate LED junction temperature from drive power, thermal resistance, and board temperature.Tj = Tref + P_diss · (θ_jc + θ_cb) , P_diss = Vf · If · (1 − η_opt)
- Optical Power Budget (dBm)Check whether a fiber link closes: subtract fiber, connector, and splice losses from Tx power and compare against receiver sensitivity.Loss = L·α + N_conn·L_conn + N_splice·L_splice , Margin = (P_tx − P_rx,sens) − Loss
- Gaussian Beam DivergenceFar-field half-angle, Rayleigh range, and spot size for a TEM₀₀ Gaussian beam from its waist.θ = M²·λ / (π·w₀) , z_R = π·w₀² / (M²·λ) , w(z) = w₀·√(1 + (z/z_R)²)