It is explicitly shown that the spatial distribution of the energy gap in a superconducting tunnel junction can be determined quantitatively. This is verified experimentally using superconducting-insulator-superconducting tunnel junctions where gap inhomogeneity is deliberately induced with patterned laser illumination.

• Received 4 December 1984

DOI:https://doi.org/10.1103/PhysRevB.31.4676