Figure 1
(a) Infrared radiation of intensity \(I_0\) is sent towards a sample with geometrical cross section g. Part of the radiation is scattered off or absorbed by the sample. The radiation that is transmitted through the sample has an intensity of I and hits a detector with a geometrical cross section equal to G. (b) Extinction efficiency found from Mie Theory, \(Q_{ext}\), and the van de Hulst approximation for \(Q_{ext}\) for a sphere of radius \(10\,\upmu \rm m\) and a refractive index of 1.3 (black line). The blue and the red lines indicate the exact extinction efficiency (described by Mie Theory) for an infinite cylinder with different polarization The radius of the cylinder is \(10\,\upmu \rm m\) and the refractive index is 1.3. (c) Norm of the wavefunction, equivalent with the norm of the electric field \(\vec{E}\), in the case where the electric field is parallel to the cylinder axis. The scatterer is a disk of radius \(10\,\upmu \rm m\) and has an index of refraction of 1.8. The incident radiation is a plane wave with wavenumber \(1643.5\,\) \(\hbox {cm}^{-1}\), an amplitude equal to one, and is propagating from the left. The wavenumber of the incident plane wave is chosen to coincide with the wavenumber of a ripple, i.e., a standing wave along the inside of the circumference of the disk-shaped scatterer. (d) Illustration of how the system evaluated in this work transforms from a disk with a radius a, that is kept constant, into a stadium of width \(2a + d\) with increasing d. The refractive index of the scatterer is m and the refractive index of the surroundings is \(m_0 = 1\). The system is an open system, i.e., light can enter the system from the outside and can leave the system to the outside. The light is incident from the top as indicated by the arrows.
