The present invention provides an apparatus and method for randomly distributing a number of fibers associated with a spectral channel over an area of an input optics head input window for sensing optical input. The head comprises a plurality of optical channels each channels having a plurality of fibers spread out and intermingled across the input optics head. Thus, a particle or gas bubble passing in front of the input optics head would temporarily affect all channels but only to a small degree since only a portion of fibers for a particular channel would be affected by the temporary passage of the bubble or particle passing in front of a particular region of the optics head input window.