Our experience in using the vendor-supplied hardware for delivering the laser beam into the microscope has been that the procedure can be a time-consuming and frustrating one. The reason for this is that the correct position of the incident beam on the microscope beam-splitter is extremely sensitive to the angle with which it enters the microscope housing. A properly aligned beam, when viewed on the microscope viewing screen with the use of a flat reflective sample, displays a sharp spot on the screen. When the focus is changed either up or down, the spot will display concentric behavior on either side of the focal point. Any subtle change to the optical path may affect the angle of entry into the microscope and, hence, its alignment, thereby making adjustments necessary. We have taken the frustration out of the alignment process by removing the vendor's turning mirror and replacing it with two mirrors on adjustable mounts, along with two apertures to define reproducibly the correct laser path. Figure 1 shows the complete optical system, which employs an argon-ion laser source, a Jobin-Yvon HG2S monochromator, and a Nachet NS400 microscope. While this is not the arrangement that would have been devised if unlimited space had been available, it has proved to be a very satisfactory one for this system.
D. P. Armstrong and W. H. Fletcher, "User-Friendly Beam Delivery for a Micro-Raman Microscope Attachment," Appl. Spectrosc. 42, 174-175 (1988)