Patent ID: 9134523
Filing Date: 2015-09-15
Classification: G02B

Abstract:
1. An apparatus for achieving predictive focusing in an image scanning system, the image scanning system being configured to scan a sample by partitioning the sample into an array of fields of view (FoVs) where focusing is individually applied to each of the FoVs and where the array of FoVs, arranged as rows of FoVs, is scanned in a raster-scanning manner, the apparatus comprising: an optical path-length changing plate comprising a plurality of path-length changing members on the plate, the plate being positioned substantially perpendicular to an optical axis of the image scanning system whereby an individual light beam traveling through the plate in a direction along the optical axis experiences a change in optical path length introduced by the plate; and an imaging sensor positioned substantially perpendicular to the optical axis for sensing an image formed by light beams after such light beams travel through the plate; wherein: the path-length changing members are positioned substantially away from the plate's center so as to form a central region of the plate; each of the path-length changing members has a light receiving surface and is configured to provide a substantially non-uniform change in optical path length across the light receiving surface when first plural light beams travel into the light receiving surface in a direction along the optical axis, such that a focus plane of a first image formed by the first plural light beams is rotated with an inclination angle relative to the imaging sensor, the focus plane of the first image being rotated around either a first reference axis orthogonal to the optical axis or a second reference axis orthogonal to both the optical axis and the first reference axis, thereby allowing a first projected image formed by the first plural light beams and projected onto the imaging sensor to be used for predicting an amount of optical adjustment required to achieve focusing; and the central region and the path-length changing members are positioned on the plate and configured such that an image appeared on a first FoV, the first FoV being one of the FoVs on the sample, is received by the central region, and such that an image appeared on a second FoV adjacent to the first FoV on the sample is received by the light receiving surface of one of the path-length changing members, whereby when the image appeared on the first FoV is captured for imaging, it is allowable that the image appeared on the second FoV after passing through the plate is substantially simultaneously captured by the imaging sensor for predicting an amount of optical adjustment required to be made for achieving focusing on the image appeared on the second FoV.