A method is provided for determining information relating to vibration. The method includes projecting an aerial image at an image position in a projection plane; mapping an intensity of the aerial image into an image map that contains values of coordinates of sampling locations and of the intensity sampled at each sampling location; and measuring intensity of the aerial image received through a slot pattern. The method may also include determining from the image map a detection position of a slope portion of the image map; at the detection position of the slope portion, measuring a temporal intensity of the aerial image and relative positions of the slot pattern and the image position; and determining from the temporal intensity of the aerial image information relating to vibration for the aerial image. The relative positions of the slot can be measured as position-related data of the slot pattern.