Parameter | Present Method | Spectroradiometric data |

λ | (i) measured with spectrometer & grating: 529 - 532 (ii) Calculated from Equation (3) with experimental t and Δn and using k = 2: (a) 525 with exact value of t (b) 498 assuming 5% increase in t (c) 551 assuming 5% decrease in t | 532 - 534 |

FWHM (nm) | 28 (calculated from Equation (3) with experimental Δn) | 30 |