•Advantages are that
the pathway is easier to define (you
know where the light is going !!)
•It is usually monochromatic light so excitation filters are
not needed
•Brighter source of
light than arc lamps (higher radiance)
•Spot size (d)
can be calculated by formula
–d=1.27(lF/D) where D is the beam diameter in mm and F is
the focal distance from
the lens
•For a 125 mm focal
length spherical lens at 515 nm is 55
um and 61 um at 458 nm