Specifications

3.4 Cateye reflector 13
35mm
Lens tube Cateye Recollimator
Figure 3.4: Arrangement oflens tube andcateye reflectorfor adjustment
of focus of cateye.
blyatabout35mmapart,withoutfilter(seeFig. 3.4).Setthediode
currentjustbelowthreshold,andthenadjustthecateyelensfocus
until the output suddenly flashesbrightly, indicating effective feed-
back whichtendsto lowerthe overall ECDLgainthreshold. Repeat
until the minimum is obtained.
The sequence is as follows:
1. Mount the lens tube and cateye reflector about 35mm apart.
2. Monitortheoutputbeamonapieceofblackcardatashort
distancefrom thecateye assembly.Itis helpfultorecollimate
the outputafter thecateye;anylenscan beused, atapprox-
imatelythefocallengthofthatlensfromtheoutputcoupler.
Monitor the beam spot using a security camera or webcam.
3. Adjust the injection current to just below threshold.
4. Adjust thecateye lensfocus untila brightflash (i.e.lasing) is
observed.
5. Iteratereduction ofthe injectioncurrent,following byfocus of
the cateye, until the minimum threshold is achieved.
6. Reassemblethelaserandadjustthefilterangletoachievethe
desired wavelength.