Method and device for radiating light used to capture iris

A mobile device for radiating light to capture an iris of a user, the mobile device comprising:

• a lens unit including a lens array of arranged lenses;
• a light source configured to radiate light beams into the iris of the user via the arranged lenses by emitting the light beams toward the arranged lenses;
• and
• at least one processor configured to change positions of the arranged lenses based on a distance between the mobile device and the iris, the changing of the positions of the arranged lenses comprising:
• sensing movement of the iris, and
• moving the arranged lenses based on the movement of the iris,
• wherein the lens array is positioned between the light source and the iris, and
• wherein movement directions of the arranged lenses are determined based on a movement direction of the iris.