Device for adjusting the composition of the spectrum of a light beam using cam plates, traction cable arrangement

摘要

A device for adjusting the composition of the spectrum of a light beam. At least one filter is adjustable at right angles to the axis of the light beam. The filter consists of two separate parts and means are provided for the joint stepwise moving of both filter parts to said axis and away from it. Thereby both filter parts are equidistant from the axis. The filter parts are moved stepwise so that the change of intensity of the light beam effected in each step remains substantially constant. The filter parts are connected to a stepping drive motor by means of traction cables the ends of which are guided over a respective cam plate which is torsionally connected to the axle of the drive motor. The cam plates have substantially the shape of a logarithmic spiral. Two spaced apart mounting plates are provided between which at least two, preferably three or four two-part filters, each with the traction cable belonging thereto, are arranged in different planes. The drive motors are positioned at the surfaces of the mounting plates.