An apparatus for reading from or writing to a near-field optical recording medium capable of detecting tilt and spherical aberration is described. With respect to emitters, the lens reduces internal reflection and reduces dispersion to increase overall efficiency. The present invention achieves the effect of improving processing performance of the control system. power supply for further enhancement of filter performance. A controller determines a reductant quality of the reductant based on the reductant quality signal and outputs a dosing rate signal based on the reductant quality. The distance separating the forward contact line and the ski tip is greater than or about 500 mm.