Course status

Course materials Lab access Everyone should have –lab book –proto board –voltmeter –jumper wires –resistor card Write name on yours –maintain -- example battery in voltmeter

Electronics maintenance tips Voltmeter has battery –turn off when not in use Soldering iron corrodes if left on all night

Course status - basics Enough to get started in lab –Machine safety –Mount assembly –Optics cleaning –Mach Zender alignment –Basic electronics -- diff amp, integrator –Soldering Lab book writeups of above skills

Next step Proficiency demonstrations –like test questions –if done correctly -- full credit –otherwise -- partial credit compare to others to be sure same performance gets same grade Written tests –first test is sample -- next class period

Lab proficiency demos Second optical mount assembly Construct and align interferometers –Michaelson –Sanac –etalon –white light interferometer Iris alignment Others ? –Spatial filter –Confocal etalon Acousto optics setup Fabry-Perot filter setup Stabilize laser intensity using simple servo –acousto-optic shifters, VCOs Lock optical spectrum analyzer (Fabry-Perot) to laser –lock-in amplifiers and ac servos, etc. Construct servo box –design and packaging of special-purpose electronics Optimize both servos and Bode plots

Soldering Steps to get good joint –Melt drop of solder on iron –Contact work –Flow solder directly on both work pieces can “tin” in advance –Last action contact with fresh flux can be in fresh solder Too much solder ? –remove with pump or wick Learn to be fast -- heat damage can result

Op amp debugging tips Check dc voltage at key pins of op amp chip –Pin 4 = -15 V, Pin 7 = +15 V if not, check power supply, grounding –Pin 6 (output) if greater than +/- 10 V -- saturated ? -- check inputs –Pin 2 (+ input) = ground (or reference voltage) if not, connect –Pin 3 (- input) = pin 2 if not -- saturated, output load impedance, bad op amp Saturated ? –Check voltage at each resistor connected to summing junction set to zero ? Feedback path closed ? -- short integrator Check ac voltage at pin 6 –MHz oscillation ? -- add capacitors on power leads –above 1 micro Farad -- electrolytic -- observe polarity

More machining Second set of mounts –learn tool change –tool sharpen (lathe) –machine setup an tear down –cleanup Testing of mounts –stability -- nothing loose or vibrating –operation -- knobs and levers work –far field test (mirrors)

Far field test -- mirrors Deflect laser beam with mirror –send long distance –shine on card and mark position –test alignment and stability laser Long distance mirror screen Laser beam marks

Iris alignment Align optical sub-assembly –interferometer ? Place irises in position –one close to second mirror –the other far from second mirror Disturb input laser beam alignment Reset alignment using only input mirrors and irises –first center on close iris (1) using mirror 1 –then center on far iris (2) using mirror 2 –iterate Input Optical sub-assembly Mirror 1 Mirror 2 Iris 1Iris 2