Waveguide Mode Effects, Birefringence and Dichroism in Fly Photoreceptors

Spectral effects of the pupil in fly photoreceptors

“…Snyder (1975). In real fly rhabdomeres V has been determined by measuring their refractive index (nl) (Beersma 1979), by measuring their birefringence (Kirschfeld and Snyder 1975) and also by measuring intensities transmitted by a rhabdomere using different sized diaphragms (McIntyre and Kirschfeld 1981). At 2=500nm the range of experimental V values for rhabdomeres type R 1-6 is 2 _< V_< 3.…”

Angular sensitivity of blowfly photoreceptors: intracellular measurements and wave-optical predictions

“…It became rapidly clear that the experimental curves could never be sensibly approximated when a single mode was assumed. Also, from knowing the value of b (Boschek 1971 ;Kirschfeld and Snyder 1975) it was evident that at 355 nm the V-number had to exceed the value V= 2.4 and sometimes also had to exceed the value V=3.8. Hence the second and third order modes were included in the analysis.…”

“…This simplest case is encountered at 588 nm, as follows from reasonable estimates of the parameter values (Kirschfeld and Snyder 1975;Beersma etal. 1982).…”

“…The range within which the parameters can be varied is, however, limited (e.g. Kirschfeld and Snyder 1975).…”

Polarization signals in mantis shrimps

“…7461 74610C-8 cell forming the retarder contains an ultraviolet-light-sensitive visual pigment, so it normally functions as an ultraviolet photoreceptor. However, its unidirectional microvilli are birefringent, as in typical arthropod photoreceptors 21 , giving it an inbuilt ability to retard circularly polarized light (Fig. 8A,B); the degree of retardance thus depends on the length of the microvillar stack.…”