Figure 6
Amplitude and phase difference of the sinusoidal fits to the analyzer angle-dependent intensity curves measured for wing membrane pieces and the refractive index dispersion. (a) Amplitudes for three immersion fluids, with refractive index (at 589 nm) nr=1.51, 1.55 and 1.60, together with T½, the square root of the transmittance spectrum calculated from Figure 4b. (b) Phase difference as a function of the refractive index of the three reference fluids (values for 589 nm are indicated by arrows) for various wavelengths, λ, together with linear fits to the data for each wavelength. The real parts of the refractive index of the object and the reference are identical when the phase difference is zero (dashed horizontal line). (c) Real part of the refractive index of the wing membrane as a function of wavelength for the red-pigmented and the clear, unpigmented wing membrane (blue symbols). The black line shows the dispersion curve for insect chitin (from Ref. 8).
