Fig. 4From: Focusing characteristics of a 4 πparabolic mirror light-matter interfaceMeasurement of the ion’s fluorescence vs. excitation power for determining the coupling efficiency (symbols). Solid lines show the results from curve fitting when illuminating half of the solid angle (red) and full solid angle (blue). To ensure constant coupling for the curve fitting, we only use data points for weak excitation (R det ≤392 cps equals S<1/10, see Appendix) which corresponds to the nearly linear region of a saturation curveBack to article page