The sharing of forwarding states between multiple traffic paths is described. The beam splitter splits the light into a first and a second optical beam, wherein the first beam is optically coupled to a reference arm including a MEMS reference micromirror which provides axial scanning and the second beam is optically coupled to a sample arm for probing a sample to be imaged. A trigger pull adjustment assembly is disposed between a second pivoting end of the sear bar and the trigger housing includes a trigger pull adjustment screw mounted in a threaded passage of the trigger housing, and a sear bar return spring abutting the trigger pull adjustment screw and inserted in a portion of the threaded passage of the trigger housing. Thus, the quick heating of the preform is safely accomplished without causing an overheating state. The liquid perfluoro-n-alkanes of the invention are useful in optical couplants, optical cements, optical elements, optical inspection media for semiconductor wafers and devices, and immersion photolithography at 157 nm exposure wavelength.