Patent ID: 7492446

Claim:
A beam catcher for a light beam ( 1 ), comprising: a photodetector ( 6 ) having a plurality of photodiodes ( 8 ) which are offset along a line in a defined manner with respect to a reference point ( 7 ); an evaluating unit ( 11 ) having a parameter set (P) of at least one associated line laser transmitter ( 2 ) for emitting the light beam ( 1 ); a quantity determining module ( 13 ) for determining an energy quantity associated with a detected light energy (L) of the light beam ( 1 ); an error estimating module ( 14 ) for determining an error estimation value (F) from a line energy density (ρ) and the parameter set (P), using an estimating function (f); a decision module ( 15 ) for comparing the error estimation value (F) to a threshold error value (G), and for generating and outputting an error signal (Θ) to a user when the error estimation value (F) exceeds the threshold error value (G), to stop the user from positioning the beam catcher with an excess total error in position; and an offset display ( 9 ) for displaying offset of the light beam ( 1 ) with respect to the reference point ( 7 ).