The beam-shaping optics define the beam parameter line length, the optimum working distance and the focussing range. The chosen laser module defines the wavelength and the power output and, thereby, the laser safety class.
The line lengths and line widths shown in the technical data are valid for the nominal working distance of the line optics. Any working distance changes do require refocussing within the available focussing range, with line width increasing in direct proportion with greater working distance.
The new low noise laser diode modules from Schäfter+Kirchhoff have reduced power noise, reduced coherence length and low speckle contrast as a result of internal RF-modulation. The low noise (<0.1% RMS, @<1 MHz) and the mode-hopping free laser operation makes these laser diode modules ideal for particle measurements or advanced medical and biotechnological applications. Due to the reduced coherence length, speckle contrast might be lowered. This effect, however, becomes smaller for thinner lines.