A system inspecting a backside surface of a wafer with multi-channel focus control comprising: a plurality of inspection sub-systems (102a; 102b; 102c; 102d; 102e) including a first inspection sub-system positionable at a first wafer position and at least an additional inspection sub-system positionable at an additional wafer position, wherein the wafer is secured at one or more edge points of the wafer; wherein the first inspection sub-system comprises: a first optical assembly; a first actuation assembly, wherein the first optical assembly is disposed on the first actuation assembly; and a first positional sensor configured to sense a position characteristic between a portion of the first optical assembly and the backside surface of the wafer; wherein the at least an additional inspection sub-system comprises: at least an additional optical assembly; at least an additional actuation assembly, wherein the at least an additional optical assembly is disposed on the at least an additional actuation assembly; and at least an additional positional sensor configured to sense a position characteristic between a portion of the at least an additional optical assembly and the backside surface of the wafer; and a controller, wherein the controller is communicatively coupled to the first actuation assembly, the at least an additional actuation assembly, the first positional sensor and the at least an additional positional sensor, wherein the controller is configured to execute a set of program instructions configured to cause one or more processors to: acquire one or more wafer profile maps of the backside surface of the wafer, wherein the acquiring the one or more wafer profile maps comprises: performing a pre-mapping process of the backside surface of the wafer in order to generate the one or more wafer profile maps with at least one of the first positional sensor or the at least one additional positional sensor; and adjust at least one of a first focus position of the first inspection sub-system or at least an additional focus position of the at least an additional inspection sub-system based on the received one or more wafer profile maps, to correct for focus offset caused by gravitation sag and/ or film induced warp in the wafer. a plurality of inspection sub-systems (102a; 102b; 102c; 102d; 102e) including a first inspection sub-system positionable at a first wafer position and at least an additional inspection sub-system positionable at an additional wafer position, wherein the wafer is secured at one or more edge points of the wafer; wherein the first inspection sub-system comprises: a first optical assembly; a first actuation assembly, wherein the first optical assembly is disposed on the first actuation assembly; and a first positional sensor configured to sense a position characteristic between a portion of the first optical assembly and the backside surface of the wafer; wherein the at least an additional inspection sub-system comprises: at least an additional optical assembly; at least an additional actuation assembly, wherein the at least an additional optical assembly is disposed on the at least an additional actuation assembly; and at least an additional positional sensor configured to sense a position characteristic between a portion of the at least an additional optical assembly and the backside surface of the wafer; and a controller, wherein the controller is communicatively coupled to the first actuation assembly, the at least an additional actuation assembly, the first positional sensor and the at least an additional positional sensor, wherein the controller is configured to execute a set of program instructions configured to cause one or more processors to: acquire one or more wafer profile maps of the backside surface of the wafer, wherein the acquiring the one or more wafer profile maps comprises: performing a pre-mapping process of the backside surface of the wafer in order to generate the one or more wafer profile maps with at least one of the first positional sensor or the at least one additional positional sensor; and adjust at least one of a first focus position of the first inspection sub-system or at least an additional focus position of the at least an additional inspection sub-system based on the received one or more wafer profile maps, to correct for focus offset caused by gravitation sag and/ or film induced warp in the wafer.