A hint: You should put the coin much closer to the calibration corner walls.
And you can focus the line by means of a cylindrical lens. But this kind of lens is not so common.
Thanks Walter for your suggestions.. I am glad peoples like you help us newbies... You all are our masters
Can you show me the picture of that lens, may be i can get it from somewhere
I think i remove one of cylindrical lens from the red dealextreme laser... I think one cylindrical lens is also inside my green laser pointer... can i place two cylindrical lens in green laser??