Fast Auto-Focus in Imaging

A method for automatically focusing multiple images of one or more objects on a substrate, the method comprising:

• a) obtaining, by one or more processing devices, a representative focal distance for a first location on the substrate based on a set of focal distances at known locations on the substrate;
• b) acquiring, by an image acquisition device, a set of at least two images of the first location based on the representative focal distance, wherein the set of images is acquired under illumination by at least two different colors and each of one or more images under a particular color is acquired using a focal distance at a corresponding offset from the representative focal distance;
• c) estimating, by the one or more processing devices, an ideal focal distance based on the acquired set of images;
• and
• d) storing the estimated ideal focal distance and the first location in the set of focal distances at known locations.

A system comprising:

• an image acquisition device configured to acquire a set of at least two images of the first location based on a representative focal distance, wherein the set of images is acquired under illumination by at least two different colors and each of one or more images under each a particular color is acquired using a focal distance at a corresponding offset from the representative focal distance;
• and
• one or more processing devices, connected to the image acquisition device, the one or more processing devices configured to:
• obtain the representative focal distance for a first location on the substrate based on a set of focal distances at known locations on the substrate,
• estimate an ideal focal distance based on the acquired set of images, and
• store the estimated ideal focal distance and the first location in the set of focal distances at known locations.

A non-transitory computer readable storage device, having encoded thereon computer readable instructions that causes one or more processing devices to execute operations comprising:

• obtaining a representative focal distance for a first location on the substrate based on a set of focal distances at known locations on the substrate;
• obtaining a set of at least two images of the first location based on the representative focal distance, wherein the set of images is acquired under illumination by at least two different colors and each of one or more images under a particular color is acquired using a focal distance at a corresponding offset from the representative focal distance;
• estimating an ideal focal distance based on the acquired set of images;
• and
• storing the estimated ideal focal distance and the first location in the set of focal distances at known locations.