quality of optical sensitivity rhabdom acceptance angle IDOMAL:0002238 IDOMAL:0002238 The rhabdoms of most insects are cylindrical in form and act as light guides, i.e. they trap and retain light by total internal reflection. The cone of light that such a cylinder can trap is narrow. The acceptance angle of the cylinder is limited by the critical angle for total internal reflection, and therefore is governed by the differenece of refractive index between the receptor itself and the surrounding cytoplasm. idomal_namespace quality of optical sensitivity