An arrangement for monitoring the emission wavelength of a laser source emitting a main radiation beam to be launched into an optical waveguide includes a wavelength selective photosensitive element adapted to be exposed to the radiation beam to generate an output signal indicative of the wavelength of the radiation. The method comprises providing at least one frequency-bandwidth limited portion of the input signal. The method of this invention also enables the use of different binding systems and precise control over mixing ratios for multi-component binders. In-land binary means calculates an in-land defect image from an original image. A Z-axis drive for the second housing is independently movable with respect to the Z-axis drive for the first housing.