Patent ID: 8243569

Claim:
A method of adjusting a tilt of an optical detection unit (ODU), comprising: receiving N detection signals A 1 to A N from N detection areas on opposite sides of an axis of the ODU, N being a positive integer number; generating a first signal (RF 1 ) equal to ∑ i = 1 N ⁢ x i × A i , wherein x i is a first weighting factor corresponding to A i ; generating a second signal (RF 2 ) equal to ∑ i = 1 N ⁢ y i × A i , wherein y i is a second weighting factor corresponding to A i , and for at least one i, x i ≈0 and y i ≈0; measuring a first value for a signal characteristic of RF 1 ; measuring a second value for the signal characteristic of RF 2 ; calculating an amount of tilt adjustment as a function of at least the first value and the second value; and adjusting the tilt of the ODU based on the amount of tilt adjustment.