An iris camera comprising a lens system, an image sensor arranged to capture images of an eye acquired by the lens system, and a processing unit, is described. The processing unit comprises an image analysis module adapted to measure pupil dilation of an image of an eye captured by the image sensor； and a control module arranged to generate a control signal to control a light source for illuminating the eye, the control module being arranged to generate the control signal to activate the light source to illuminate the eye when the measured pupil dilation is greater than a predetermined threshold.
