The singular limit is approached by simultaneously increasing the voltage (V = 1.03, 1.23 and 1.33 eV from top to bottom) between a graphene sheet and an array of 160 nm-thick gold wires, and down-shifting the chemical potential of the whole sheet by a constant value (−0.11, −0.24 and −0.30 V from top to bottom). The increasingly high (blue to cyan lines) losses, corresponding to electron mobilities 2 × 10⁴, 1 × 10⁴ and 5 × 10³ cm²/(V s) result in a faster merging of the spectrum due to smearing of the transmittance dips. The dielectric function of gold is obtained from experimental data [47].