Method for determining a best initial focal position estimate

A method for autofocusing sample locations on a substrate comprising:

• a) determining a focal position for a first sample location on the substrate and a second sample location on the substrate;
• b) estimating a best initial focal position for a third sample location on the substrate by using a result from linear regression analysis of the focal position for the first sample location and the second sample location;
• c) focusing to obtain a focal position for the third sample location;
• d) estimating a best initial focal position for a fourth sample location on the substrate by using a result from one or more techniques selected from the group consisting of:
• A) linear regression analysis of focal positions determined for at least two other sample locations on the substrate and B) quadratic regression analysis of focal positions determined for at least three other sample locations on the substrate
• e) focusing to obtain a focal position for the fourth sample location;
• and
• f) repeating steps d) and e) for a desired number of sample locations on the substrate.

A machine readable storage medium comprising a program containing a set of instructions for causing a cell screening system to execute a set of procedures for autofocusing sample locations on a substrate containing multiple sample locations, wherein the procedures comprise:

• a) determining a focal position for a first sample location on the substrate and a second sample location on the substrate;
• b) estimating a best initial focal position for a third sample location on the substrate based on linear regression analysis of the focal position for the first sample location and the second sample location;
• c) focusing to obtain a focal position for the third sample location;
• d) estimating a best initial focal position for a fourth sample location on the substrate by using a result from one or more techniques selected from the group consisting of:
• A) linear regression analysis of focal positions determined for at least two other sample locations on the substrate and B) quadratic regression analysis of focal positions determined for at least three other sample locations on the substrate e) focusing to obtain a focal position for the fourth sample location;
• and
• f) repeating steps d) and e) for a desired number of sample locations on the substrate.