Note: The linewidths you just calculated are actually about a factor of 3-4 bigger than what is actually achievable. The difference arises partly from the fact that the resilience of the photoresist depends on the amount of exposure, which in turn depends on the intensity of the light. Thus, the resulting metal strip is only a fraction as wide as the null-to-null distance. Assuming the size of the traces is the only constraint limiting the 'areal density' (i. e., how many components can be laid out per square centimeter), by what factor does the areal density increase in going from a writing laser with λ = 248 nm to one with λ = 157 nm?