Fig. 9.7 — Longitudinal forward scattering and longitudinal position detection

Longitudinal forward scattering and longitudinal position detection. (a) Images of the field at the back focal plane of the condenser for various particle radii a and particle longitudinal displacement C = [0, 0, C_z]. The circles delimit the areas of the field that is captured by the condenser lens with NA_o = 0.20, 0.65 (solid line) and 1.20 from the centre outwards. (b) Signal from a QPD as a function of C_z for the case of a = 400 nm (dotted line), a = 600 nm (dashed line) and a = 1000 nm (solid line) for an incident beam with power 1 mW and detection NA_c = 0.65 (black lines) and 1.20 (grey lines).