Correction for illumination non-uniformity during the synthesis of arrays of oligomers
The present invention provides an apparatus and a method for the synthesis of arrays of oligomers that have tight illumination intensity requirement. The apparatus and the method contains a mechanism to correct for illumination nonuniformity during the oligomer array synthesis process. To correct for illumination nonuniformity, the illumination intensity of different oligomer synthesis positions across an area in which oligomers are synthesized are determined first. Then, the difference in illumination intensity among the positions are evaluated mathematically. Next, any nonuniformity in illumination intensity is corrected by either reducing the intensity of the light for the brighter positions before the light reaches the illumination area or reducing the illumination time of the brighter positions during one protection group deprotection period.
1. A method for correcting illumination nonuniformity across an illumination area during the synthesis of an array of oligomers from monomers, the illumination areas being illuminated by light directed to the illumination areas by a micromirror array during a common deprotection period, the method comprising the steps of:
measuring the illumination intensity of at least two oligomer synthesis positions at different positions in the illumination area, each of the synthesis positions corresponding to a single micromirror in the micromirror array;
evaluating mathematically the difference in illumination intensity between the at least two oligomer synthesis positions to identify a first synthesis position illuminated more brightly and a second synthesis position illuminated less brightly; and
correcting illumination nonuniformity by adjusting the illumination intensity of the light directed to the first synthesis position to match that of the light directed to the second synthesis position during the deprotection period by reducing the illumination time in which the micromirror corresponding to the first synthesis position directs light to the first synthesis position as compared to the illumination time in which the micromirror corresponding the second synthesis position directs light to the second synthesis position by switching the micromirror which directs light to the first synthesis position so as to direct light away from the first synthesis position for a portion of the deprotection period.
2. The method of claim 1 , further comprising the steps of:
measuring the adjusted illumination intensity of each oligomer synthesis position; and
further adjusting the illumination intensities of each of the synthesis positions for higher uniformity across the entire illumination area.
3. The method of claim 1 , wherein the measuring step comprises the steps of:
covering the at least two oligomer synthesis positions with a first protected nucleotide;
directing an amount of deprotecting light to each covered position via the micromirror corresponding to the covered position, the amount of light being insufficient to fully deprotect each covered position;
binding to the deprotected first nucleotide at each position a complimentary phosphor-linked second nucleotide; and
measuring the illumination intensity of the bound phosphor-linked second nucleotide at each position.
4. The method as claimed in claim 3 wherein every oligomer synthesis position is covered with the first protected nucleotide.
5. A method for correcting illumination nonuniformity across an illumination area during the synthesis of an array of oligomers from monomers, the illumination area being illuminated by light directed from a micromirror array to the illumination area during a deprotection period, the method comprising the steps of:
measuring the illumination intensity of at least two oligomer synthesis positions at different positions in the illumination area, each of the positions corresponding to the light directed from a micromirror in the micromirror array;
evaluating mathematically the difference in illumination intensity between the at least two oligomer synthesis positions, the evaluation revealing that a first synthesis position is more brightly illuminated than a second synthesis position which is less brightly illuminated; and
correcting illumination nonuniformity by adjusting the illumination intensity of the light directed to the first synthesis position during the deprotection period to match that of the light directed to the less brightly illuminated synthesis position during the deprotection period, the adjustment being accomplished by decreasing the portion of the time during the deprotection period that light is directed by the micromirror to the first synthesis position so that the total amount of light directed to the first synthesis position is equivalent to the total amount of light delivered to the second synthesis position.
6. The method of claim 5 , wherein the measuring step comprises the steps of:
covering the at least two oligomer synthesis positions with a first protected nucleotide;
directing an amount of deprotecting light to each covered position via the micromirror corresponding to the covered position, the amount of light being insufficient to fully deprotect each covered position;
binding to the deprotected first nucleotide at each position a complimentary phosphor-linked second nucleotide; and
measuring the illumination intensity of the bound phosphor-linked second nucleotide at each position.
7. The method as claimed in claim 6 wherein every oligomer synthesis position is covered with the first protected nucleotide.