Thin Film Interference Conditions
Constructive and destructive interference patterns from a single thin film, accounting for phase shifts at boundaries.
Net reflection phase shift (from the index order)
0 (both or neither reflection off a higher index)
Optical Path Difference
276.0 nm
Longest constructive λ (m = 1)
276.0 nm
Longest destructive λ
552.0 nm
Interference Conditions
OPD = 2·n·d (normal incidence)
Net phase 0: constructive 2nd = mλ, destructive 2nd = (m+½)λ
Net phase π: constructive 2nd = (m+½)λ, destructive 2nd = mλ
Each reflection off a higher index adds π
Model and references
Exact. The equations are exact within the stated assumptions, or are a standard's tabulated values. The results are as good as the inputs. About the tiers
A lossless single film between semi-infinite media at normal incidence, constant indices. The extrema of the exact R(λ) lie at 2nd = mλ or (m + ½)λ, depending on the index order.
- Hecht E. (2016). Optics, 5th ed., §9.4 (thin-film fringes, phase change on reflection).
- Born M., Wolf E. (1999). Principles of Optics, 7th ed., §7.6.1. Cambridge University Press.
- Macleod H. A. (2010). Thin-Film Optical Filters, 4th ed., ch. 2. CRC Press. doi:10.1201/9781420073034