for the Maskless Array Synthesis ..
Nimblegen Maskless Array Synthesis
A schematic of the optical system of the maskless array synthesizer is shown in Figure . Loss of optical contrast is mainly due to two factors, flare (scattering) and diffraction. Global flare originates from dust and imperfections in the optical system and results in a spatially homogenous background exposure that is proportional to the total number of ON mirrors as shown in Figure . In this experiment, a calibrated intensity meter is placed at the focal plane (replacing the synthesis cell), with a mask blocking all but a small central area of the light-sensitive surface as shown with the label "UV-detector" in Figure . With all the mirrors that direct light directly to the detector turned OFF, the measured signal is primarily from global flare irradiance originating from ON mirrors that do not image into the detector. At the high end of number of ON mirrors, 64%, we were able to measure a global flare irradiance of 0.1% of direct irradiance using a calibrated intensity meter. This corresponds to a global flare of less than 0.04% of synthesis irradiance for a 1:1 layout (all mirrors used) high density microarray, where an average of 25% of the mirrors are used in each deprotection step. This corresponds to a contrast ratio of better than 1/2500 (global flare only).
Looking for online definition of array synthesis in the Medical ..
Maskless array synthesis relies on the effective removal of the 5'-NPPOC hydroxyl protecting group of oligonucleotides prior to coupling a new base. The rate of photochemical removal of this group is directly proportional to light intensity and the number of remaining protecting groups: