Patent ID: 9229212
Filing Date: 2016-01-05
CPC Classification: G02B

Claim Text:
1. An image acquisition apparatus comprising: a sample stage for placing a sample as an image pickup object thereon; an image pickup device capable of acquiring a two-dimensional image whose longitudinal direction is along a first direction and TDI driving; an image pickup optical system including an objective lens disposed between the sample stage and the image pickup device; a scanner for acquiring an observation image by the image pickup device and the image pickup optical system while scanning the sample in a second direction different from the first direction; and focus oscillation controller for controlling oscillation of a focus in the sample so that the image pickup focus in the sample to be set by the image pickup optical system oscillates at a predetermined oscillation frequency fs in an optical axis direction with respect to the sample, wherein the focus oscillation controller sets the oscillation frequency fs, with respect to an image pickup period Ti that is determined by a charge transfer rate and the number of transfer pixels in TDI driving in the image pickup device, so that the oscillation frequency fs coincides within a predetermined range with Ns times (Ns is an integer not less than 1) the basic frequency, the basic frequency being a reciprocal 1/Ti of the image pickup period.