An important feature of any advanced lithography technology is its cost-effective extension over several device generations beyond its introduction. Since SCALPEL is an electron imaging system with resolution not limited by diffraction, a unique extensibility analysis is deeded to establish development pathways for the evolution of SCALPEL to the 50 nm generation and beyond. A combination of modest progress in four performance areas-effective optical field width, aberrations, acceptable dose latitude, and stage performance-will allow SCALPEL to maintain good throughput over several lithography generations without aggressive optical design scaling.