Image-acquisition apparatus and image-acquisition method

1. An image-acquisition apparatus comprising:

a scanning portion that scans illumination light emitted from a light source;

an optical system that focuses the illumination light scanned by the scanning portion on a sample, while collecting signal light beams generated at the individual scanning positions on the sample;

a detector that detects the signal light beams collected by the optical system and that generates detection signals thereof;

a controller that is configured to generate periodic signals that are repeated at a predetermined period;

a light controller that is configured to temporally control a position or an intensity of the illumination light in accordance with the periodic signals generated by the signal controller; and

a computer that is configured to process, in accordance with the periodic signals generated by the signal controller, the detection signals generated by the detector,

wherein the computer is provided with a frequency shifter for shifting the frequency of the detection signals by an amount corresponding to the period of the periodic signals generated by the signal controller, and an integrator that integrates the detection signals, which have been shifted by the frequency shifter, at an integration time that is an integer multiple of the period of the periodic signals.

2. An image-acquisition apparatus according to claim 1 , wherein the light controller alternately switches the position or the intensity of the illumination light between two states thereof in accordance with the periodic signals.

3. An image-acquisition apparatus according to claim 1 , wherein the signal controller adjusts, with reference to the periodic signals to be input to one of the light controller, the frequency shifter, and the integrator, phases of the periodic signals to be input to the other two components so that the other two components are operated together.

4. An image-acquisition apparatus according to claim 3 , wherein the signal controller is provided in one of the light controller, the frequency shifter, and the integrator.

5. An image-acquisition apparatus according to claim 1 , further comprising:

an A/D converter that converts the detection signals to digital signals,

wherein the frequency shifter assigns digital signs to the detection signals in accordance with the periodic signals, and

the integrator performs digital integration.

6. An image-acquisition apparatus according to claim 5 , wherein the A/D converter has an offset adjusting function.

7. An image-acquisition apparatus according to claim 1 ,

wherein the illumination light beams are radiated on to the sample via a plurality of pathways, and

at least one of the light controller, the signal controller, and the computer is provided in multiple units so as to correspond to the individual illumination light beams that travel via the individual pathways.

8. An image-acquisition method comprising:

a modulating step of temporally controlling, in accordance with periodic signals that are repeated at a predetermined period, a position or an intensity of illumination light emitted from a light source;

a scanning step of scanning the illumination light controlled in the modulating step on a sample;

a detecting step of detecting signal light beams generated at the individual scanning positions scanned in the scanning step and generating detection signals thereof;

a frequency shifting step of shifting frequencies of the detection signals generated in the detecting step by an amount corresponding to the period of the periodic signals; and

an integrating step of integrating the detection signals, which have been shifted in the frequency shifting step, at an integration time that is an integer multiple of the period of the periodic signals.