The mirror extending substantially completely across said internal passageway ensures that a maximum of the ultraviolet radiation entering {HEAD ~ the housing} is available for exciting kerogen in {TAIL ~ the sample} and causing it to fluoresce, i.e. emit radiation at a wavelength higher than said first wave length 
The mirror extending substantially completely across said internal passageway ensures that a maximum of the ultraviolet radiation entering { HEAD ~ the housing } is available for exciting kerogen in { TAIL ~ the sample } and causing it to fluoresce , i.e. emit radiation at a wavelength higher than said first wave length
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH