This process was simulated digitally, translating the 5×5 PSF write spot array between each laser pulse to model the laser beam scanning with arrays of two different PSF to represent the 100× NA 1.40 (Fig. ) and the 40× NA 0.95 (Fig. ) objectives. A satisfactory agreement with the experimentally observed structures was again obtained, limited to some extent by the coarse simulation grid (200 nm) imposed by the heavy simulation load. We simulated with a number of pulses corresponding to 200 nm steps at the considered scan rate (2.4 µm.s -1 here), meaning about 975 pulses par sampling grid position. As before, the simulated diffusion kernel σ value and the decay factor were adapted empirically to fit the simulations to the experimentally observed structures. This resulted in the parameters shown in Table indicating a stronger diffusion behaviour in the PR_hybrid resist. A decay factor of 0.99999 gave the best fit, corresponding to a diffusing species half-life of 5.9 s, which seems again in good agreement with previously reported values for radical species, although this lifetime is longer than that calculated in PR_organic for reasons that will be discussed later. Calculations hence confirm that stronger focusing of the light results in a reduced overlap of the high intensity part of the light beams with the higher NA objective for a given inter-spot distance. As expected, the use of higher NA objectives helps to reduce the spatial extent of the PSF, making this technique a way to minimize overlap and thus reduce specific proximity effects in parallel TPP. Interestingly, in the case of these L-shaped structures, the simulations seem to reproduce not only the spatial component (decreased polymerization threshold from the periphery to the center) but also the temporal component (decreasing polymerization threshold with increasing manufacturing time as indicated by the larger and higher structures written towards the end of the plot) of the proximity effect, thereby confirming the probably crucial role of species diffusion in the overall process.