Image detection device, pulsed illumination device, and pulsed illumination method

An image detection device comprising:

• a liquid resonant lens system whose focal point is cyclically changeable;
• an image detector configured to detect an image of an object through the lens system;
• a pulsed illuminator configured to provide pulsed illumination to the object in synchronization with the focal point;
• and
• an illumination controller configured to control the pulsed illuminator such that the pulsed illuminator provides repetitive pulsed illuminations to the object for a predetermined period within a variable range of the focal point, and wherein
• the pulsed illuminator comprises a main illumination section and a supplementary illumination section, and
• the illumination controller is configured to provide pulsed illumination to the object with the main illumination section, and to supplement illuminance on the object with the supplementary illumination section when the illuminance on the object by the main illumination section is equal to or less than a predetermined threshold.