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Updated: Aug 9, 2026
Single-Digit Nanometer Electron-Beam Lithography with an Aberration-Corrected Scanning Transmission Electron Microscope
Published on: September 14, 2018
Surface roughness in PMMA is linearly related to the amount of excimer laser ablation
C B O'Donnell1, J Kemner, F E O'Donnell
1O'Donnell Eye Institute, St. Louis, MO 63122, USA.
Objective:
To determine if surface roughness after excimer laser ablation is a function of the amount of ablation and to identify a standard unit for ablation roughness.
Methods:
We used a VISX 20/20 excimer laser to perform a series of single zone 6-mm diameter ablations (photorefractive keratectomy [PRK]) in polymethylmethacrylate (PMMA). Corrections ranged from -1.00 diopter (D) to -15.00 D. A scanning white light interferometry microscope (Zygo Corp, Middlefield, Conn) was used to quantify the surface roughness at the center of each ablation.
Results:
We found a linear increase in surface roughness as the refractive correction increased. Each diopter increment resulted in an approximately 300 nm increased peak-to-valley measurement. This represented an increase of 25 nm roughness per micron of ablation in PMMA.
Conclusions:
Surface irregularities in PMMA increase with ablation depth. We propose a unit of measure of roughness, the "ablation," expressed as the peak-to-valley distance in nm/divided by m of ablation.
