Short-range Gravity experiment using digital image analysis

According to a large extra dimension model, a deviation from Newton's inverse square law is expected at below sub-millimeter range. We have developed an experimental set up using a torsion balance pendulum and an online digital-image analysis system, aiming to test the Newtonian inverse square law at below millimeter scale. In addition, composition dependence of gravitational constant G is also tested at a millimeter scale, motivated to test the weak equivalence principle. In this paper, current status and results are described.