Detail of the laser stand.
The mechanical assembly allows the laser to be moved
in 4 different directions: horizontally perpendicularly to the picture
plane, vertically and horizontal and vertical tilts.
Horizontal motion is made with a Proxxon XY table.
Vertical movement is build with a modified lab jack: 4 guiding bars have been
added to the original device, 2 springs, one on each side, prevent any
backlash. A photographical tripod head is used for tilting in 2
Laser and optical elements are secured on a
polyethylene plate on top of the tripod head.
Two filters have been placed in front of the
laser: one to isolate the laser line and a second one to remove any
spurious infrared light, a safety precaution to avoid eyes injury.
A new beam expander (3 X) consisting of 2 lenses, one
concave (f= -50 mm) and one convex (f = 150mm) has been constructed. This
simple optical device improves the focusing of the laser beam in the
microscope object plane.