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diff --git a/procedures/chapter.tex b/procedures/chapter.tex index fcac88e..fd04bc3 100644 --- a/procedures/chapter.tex +++ b/procedures/chapter.tex @@ -1,54 +1,81 @@ \chapter{Procedures} \clearpage -\section{Starting the Millenia V CW LASER.} +\section{``Six-month'' maintenance} % ------------------------------------------------------------ -The Millennia has problems with ‘thermal runaway’ upon startup if a user naively sends the laser to -4.0 W in power mode (thermal runaway causes the infamous FAULT 146 system shut off, power adjust -timeout error). % -The following procedure wakes the Millenia up gently enough to prevent thermal runaway. % -It assumes that the Millenia starts completely shutdown and cold. % +The laser system that the Wright Group's MR-CMDS instruments use requires regular maintenance. % +Each component is sensitive to lab conditions such as temperature, humidity, and vibrations. % +Small deviations in upstream components can cause large problems in downstream optics. % +Regular maintenance involves ``tune-up'' of upstream components so that upstream lasers function +well and ideally couple into downstream lasers. % + +Historically, the Wright Group has engaged in reactive maintenance: a ``fix it if it's broken, +don't touch otherwise'' kind of approach. % +This approach makes a lot of sense for instruments that are quick to fix, and have few active +users. % + +I instituted a proactive, regular maintenance procedure (described below) that has improved the +predictability of instrumental performance. % +Predictability is key for instruments with multiple users. % +Supplies needed: \begin{denumerate} - \item Check desiccant inside Millenia, replace if pink. - \item Ensure that Millenia shutter is closed such that no light is going downstream. % - \item Flip orange power switch on diode box. - \item Wait for system to warm up ($\sim$30 minutes). + \item 5 gallons distilled water. + \item Filters. \begin{denumerate} - \item ``System Warming Up'' message should appear on control box. - \item Warm-up is finished when percentage complete indicator reaches 100. - \item The Millenia will start in SP Current mode. + \item 2x 5 micron Liquatec SDF-25-0505 + \item 2x 20 micron general purpose water filter (sold in stockroom) \end{denumerate} - \item Record diode hours (choose ``Info'', scroll down). - \item Turn Millennia to 1.0 W in ``power mode'', wait for equilibration. + \item Nalco fluids. + \begin{denumerate} + \item 4 gallons Nalco 460-PCCL104 (the pink stuff). + \item 1 gallon Nalco 460-CCL2567 (the clear stuff). + \end{denumerate} + \item 150x 5 mg activated charcoal packets (Newport Part \# 90035762) \end{denumerate} - -Turn Millennia to 1.0 W in “power mode”, wait for it to equilibrate. This entails the diode temperature and current being stable (within 0.1) over 5 minutes. -Turn Millennia to “current mode”. -Slowly ramp current until you have ~4 W (or more) (~70%) -Allow the diode temperature to stabilize while remaining in “current mode” (check every 5 minutes until it doesn't change by more than 0.1) -Turn Millennia to 4.0 W “power mode”. -Wait 10 minutes for extra assurance of equilibration. -Ensure again that temperature and current are not changing (over ~5 minute timescale). -Measure and record actual Millenia output power, currents, temperatures. -These data should be recorded in the GoogleSheet document for Millennia. +Procedure: +\begin{denumerate} + \item Turn off all lasers in lab. + \item In no particular order: + \begin{ditemize} + \item Computers in lab. + \begin{denumerate} + \item Backup contents. + \item Uninstall unnecessary software. + \item Update all necessary software. + \item Restart. + \end{denumerate} + \item Chiller maintenance. + \begin{ditemize} + \item See x + \item See y + \item See z + \end{ditemize} + \item Lab cleaning. + \begin{denumerate} + \item Mop the floor, trying to get as much dust as possible. Sweeping in the laser lab is + discouraged, because it knocks more dust into the air and onto the lasers. + \item Take out trash. + \item Empty homeless cables box. + \item Empty homeless screws box. + \item Organize any cabling mess. + \item Remove unused components (optics, electronics, cabling, etc) from laser tables and + surroundings. Place into appropriate locations. + \item Organize optics cabinet. + \item Organize electronics bench. + \end{denumerate} + \end{ditemize} + \item Let lab sit overnight to allow dust to settle and the air to dehumidify. + \item Start up system again. + \begin{denumerate} + \item TODO + \end{denumerate} +\end{denumerate} \clearpage -\section{Calibrating the 407A} +\section{Lytron Kodiak RC006} % ------------------------------------------------------------------ -Calibrating the 407.A - -You may sometimes notice that the zero position changes dramatically from sensitivity to -sensitivity with the 407A. If this happens, iterate through the following until zero stays -consistent: - -Use the fine adjust (knob on side) to zero the 407A on the highest sensitivity - -Use the front adjust (flathead screwdriver needed) to zero on the lowest sensitivity - -\clearpage -\section{Lytron Kodiak RC006 We have one Lytron Kodiak RC006: Model Number RC006G03BB1C002, Serial Number 739383-02. Regular chiller maintenance: @@ -83,7 +110,7 @@ Ideally the pressure drop across this loop is sufficient to still drive fluid th % TODO: figure \clearpage -\section{PolyScience 6000 Series} +\section{PolyScience 6000 Series} % -------------------------------------------------------------- We own two PolyScience chillers---different models but functionally equivalent. @@ -115,25 +142,534 @@ Regular chiller maintenance: \end{denumerate} \end{denumerate} -% TODO: figure - \clearpage -\section{NesLab Merlin M33} +\section{NesLab Merlin M33} % ==================================================================== + +We have one NesLab Merlin M33 Chiller, Serial Number 106227049. % + +This chiller serves four different lasers on the ultrafast system. % +The cycle goes chiller out $\rightarrow$ Millennia $\rightarrow$ Tsunami $\rightarrow$ Spitfire Ace +$\rightarrow$ Spitfire Pro $\rightarrow$ chiller return. + +Regular chiller maintenance +\begin{denumerate} + \item Gather supplies. + \item Drain system completely. + \item Clean chiller internals. + \item Disconnect tubing, plug return. + \item Remove old filter from chiller, discard, replace filter holder. + \item Drain system completely and flush with several gallons of distilled water (should require + 2), until no suds are formed as new water goes through system. + \item Fill system with one gallon distilled water, circulate for at least 15 minutes, then drain + completely. + \item Place new filter into chiller. + \item Reconstruct tubing to include lasers in cycle. Ensure that cycle direction is correct. + \item Fill system with one gallon Nalco 460-PCCL104 (the pink stuff). + \item Turn chiller on, and allow system to flow for a while to get air bubbles out. + \item Top off with distilled water until chiller and tubing is full. +\end{denumerate} + +% TODO: figures \clearpage -\section{Aligining TOPAS-C} +\section{Calibrating the 407A} % ================================================================= + +Calibrating the 407.A + +You may sometimes notice that the zero position changes dramatically from sensitivity to +sensitivity with the 407A. If this happens, iterate through the following until zero stays +consistent: + +Use the fine adjust (knob on side) to zero the 407A on the highest sensitivity + +Use the front adjust (flathead screwdriver needed) to zero on the lowest sensitivity \clearpage -\section{Aligning Spitfire PRO} +\section{Millenia} % ============================================================================= + +\subsection{Startup} % --------------------------------------------------------------------------- + +The Millennia has problems with ‘thermal runaway’ upon startup if a user naively sends the laser to +4.0 W in power mode (thermal runaway causes the infamous FAULT 146 system shut off: power adjust +timeout error). % +The following procedure wakes the Millenia up gently enough to prevent thermal runaway. % +It assumes that the Millenia starts completely shutdown and cold. % + +\begin{denumerate} + \item Check desiccant inside Millenia, replace if pink. + \item Ensure that Millenia shutter is closed such that no light is going downstream. % + \item Flip orange power switch on diode box. + \item Wait for system to warm up ($\sim$30 minutes). + \begin{denumerate} + \item ``System Warming Up'' message should appear on control box. + \item Warm-up is finished when percentage complete indicator reaches 100. + \item The Millenia will start in SP Current mode. + \end{denumerate} + \item Record diode hours (choose ``Info'', scroll down). + \item Turn Millennia to 1.0 W in ``power mode'', wait for equilibration. + \begin{ditemize} + \item Equilibration occurs when diode temperature and current are stable (within 0.1) over 5 + minutes. % + \end{ditemize} + \item Switch Millennia to ``current mode''. + \item Slowly ramp current until you have more than 4 W output (probably $\sim$70\%). + \item Again, wait for diode temperature and current equilibration. + \item Switch Millennia to ``power mode'' at 4.0 W. + \item Ensure one last time that diode temperature and current are not changing over 5 minute + timescale. + \item Measure and record actual Millenia output power, currents, temperatures. +\end{denumerate} + +\subsection{Toggling service mode} % ------------------------------------------------------------- + +On the control board inside the laser, DIP switch \#4 toggles service mode. % +Service mode unlocks special SP modes. % +These allow us to record things like Diode hours. % +Service mode can be buggy, so it's best to leave the Millenia in normal Power mode during regular +operation. % \clearpage -\section{Air Handling} +\section{Spitfire Pro} % ========================================================================= + +Only tune up the Spitfire if you need to, and do not treat it casually---set aside an entire +day. % +Merely opening the spitfire box exposes the optics to dust. % +Treating the Spitfire with the respect it deserves will only save time in the long run. % + +The Spitfire contains 70 charcoal packets. % +These should be replaced every $\sim$6 months. % + +\subsection{Startup} % --------------------------------------------------------------------------- + +Spitfire Pro startup procedure, from cold. + +\begin{denumerate} + \item Ensure that the software is closed on control laptop. + \item Turn on Empower power supply (orange switch). + \item Turn on Timing and Delay Generator ``TDG'' (orange switch). + \item Turn on temperature control box (orange switch). + \item Turn key on Empower power supply. + \item Turn key on TDG. + \item Start Spitfire software. + \begin{ditemize} + \item Often have many faults, most will clear immediately. + \item Empower LBO temp fault may take a while to clear---normally clears after 5 minutes. + \end{ditemize} + \item If Empower has been off (totally, or just at zero amps), warm up at 20 Amps for 1 hour. + \begin{ditemize} + \item Use a \textit{good} beam block to block entry into the Cavity during this time. % TODO: figure + \end{ditemize} +\end{denumerate} + +\subsection{Common alignment} % ------------------------------------------------------------------ + +\subsubsection{Preparation} + +\begin{denumerate} + \item Check desiccant in temperature control box (blue is good, pink is bad). + \item Connect the fast oscilliscope so that you can see the pulse train. + \item If Spitfire is off, go through startup procedure. % TODO: link to section + \item If it has not been done in awhile, measure and record an Empower power curve. % TODO: link + % to section + \item Place the 407A after the telescope between the large square mirrors on the empty mount. + \begin{ditemize} + \item This mount is dedicated for this purpose, and should be left in the Spitfire at all + times. + \end{ditemize} + \item Set Empower current such that the Empower is delivering $\sim$20 W to the crystal (refer to + Empower power curve). +\end{denumerate} +\subsubsection{Cavity and pump} + +The first goal in alignment will be to ensure that the cavity and pump are healthy without +seeding (in ns-lasing mode). % +A well-aligned Spitfire will deliver 5 to 5.2 W to the 407A when pumped with 20 W. % +The idea of this procedure is to be minimally invasive, while demanding good performance from the +laser. % +Do not move on to seeded operation until ns-lasing is healthy, but at the same time do not do more +then you need to. % + +\begin{denumerate} + \item Switch to ns lasing mode. + \begin{denumerate} + \item Block seed at output of stretcher. + \begin{ditemize} + \item Note that seed must still enter the stretcher with good enough alignment to defeat + the bandwidth detector. + \end{ditemize} + \item Activate Pockels Cells 2 and 3---do not use Pockels Cell 1. + \item Expect 20 to 30 ns (2 to 3 round trips) additional build-up time in ns operation. + \begin{ditemize} + \item Means you must change timing of Pockels Cell 3 when working in ns lasing mode. + \item Operate the laser at its ideal switch out time when aligning ns lasing. + \item Refer to the records to see if your switch-out time is unusual for recent + performance. + \end{ditemize} + \end{denumerate} + \item Clean all green optics in order of light hitting them. + \begin{ditemize} + \item You must get new spectrophotometric grade methanol for this cleaning. + \end{ditemize} + \item Loop through the following until ns lasing delivers more than 5 W to the 407A. + \begin{denumerate} + \item Check to ensure no optics are damaged, have dust on them etc. + \item Clean optics. Check power after each cleaning---at the very least you don't want to + lose power. When cleaning, wait at least a second before letting the light hit the optic + after cleaning. + \item Align pump. + \begin{denumerate} + \item Decrease the pump power to $\sim$17 A. This should decrease the ns lasing output to + around 2 Watts, so you should can increase the sensitivity on the 407A if you wish. + \item Find the ideal switch out (channel 3) time for this lower pump power. It will be + still later than the aforementioned ns lasing switch out time. Back off the ideal ns + switch out time by $sim$2 round trips for optimization. + \item Typically the two mirrors on either side of the cavity (immediate to the lenses) + are the only pump mirrors touched during alignment. The first pump mirror may be + touched in special cases but not for regular touch-up. + \item Block the back reflection with the mirror mount when aligning the second pump + mirror. % TODO: figure + \item Align the back reflection mirror (without beam block). + \item Iterate through the mirrors until you are satisfied that pump poynting is ideal. + \end{denumerate} + \item Align cavity. + \begin{ditemize} + \item Never touch anything except the two outermost end mirrors. + \item Note that the alignment tool is poor to the cavity mode intentionally. + \end{ditemize} + \end{denumerate} +\end{denumerate} + +\subsubsection{Seed} + +Now that the cavity is good, you mus couple the seed into it. % +If you have just aligned the oscillator you should wait at least 10 hours before attempting to +align the seed. % + +Expect 100 to 150 mW less in seeded mode. % + +\begin{denumerate} + \item Remove stretcher cavity flange, being careful not to damage wires. + \item Align the two apertures either side of the Faraday isolator using mirrors external to + spitfire. + \item Align to two ``A'' mask positions in stretcher. + \item Align to three ``F'' mask positions on the way to cavity (this mirror system is + under-constrained; consider using the final mirror of the ``A'' mask alignment as a tweaking + mirror). + \item Let seed into cavity by turning on channel 1. + \item Optimize (mirror at D18 and periscope) to putput power before compressor---often useful to + go one or two round trips less ($\sim$210 ns on channel 3) when aligning seed to power (output + depends on seed more sensitively and you want to optimize for largest buildup reduction + time). + \item Can adjust quarter waveplate to minimize post-pulsing if necessary but be very careful to + not send the output back into the stretcher. + \item Ensure pulse is let out of the cavity at the optimal time (check oscilloscope and power). + \item Remove 407A. + \item Reconstruct flanges on stretcher cavity. +\end{denumerate} + +\subsubsection{Output} + +Now you must ensure that the cavity output is properly routed through the telescope and compressor +before leaving the Spitfire. % + +Note that only $\sim$80\% of the cavity output power transmits through the compressor due to +absorbance in the grating and other losses. % + +\begin{denumerate} + \item Align to compressor positions (two ``H'') using backwards alignment tool. You will need to + unplug the compressor stage cable---remember to plug back in. + \item If the cavity or pump was touched, consider aligning the compressor. +\end{denumerate} + +\subsubsection{Cleanup} + +\begin{denumerate} + \item Make sure you have taken all of your tools out of the laser. + \item Make sure you remembered to plug the compressor stage back in. + \item Wait at least 2 hours before moving on to downstream alignment---best to wait overnight if + you can. It's OK to make a first pass at rough alignment, but compression and pointing will + probably change slightly as the laser equilibrates. +\end{denumerate} + +It's normal for the Spitfire output power change by 50 to 100 mW in the first days after +alignment. % +After that initial change the Spitfire tends to be stable for weeks. % +During experiments it's a good idea to measure Spitfire output on a daily basis. % + +\subsection{Stretcher alignment} % --------------------------------------------------------------- + +This is our current best strategy for stretcher alignment. % +Use caution and keep your brain in gear when working on this. % +Since we have not messed with the stretcher frequently this guide cannot be trusted blindly. % + +\subsubsection{Preparation} + +\begin{denumerate} + \item Ensure that the Spitfire is off (no pump present in cavity, Pockels cells powered down). + \item Force upstream oscillator to go CW, adjust output color to be at center of mode-locked + bandwidth. + \item Use external mirrors to align through Faraday isolator. + \item Use first two mirrors after isolator to alignment tool prior to stretcher grating. +\end{denumerate} + +\subsubsection{Adjustment} + +\begin{denumerate} + \item Adjust the stretcher grating until the four dots are overlapped. + \item Use pickoff mirror after stretcher to get the beam to alignment tool. +\end{denumerate} + +\subsection{Compressor alignment} % -------------------------------------------------------------- + +\begin{denumerate} + \item Use the first telescope mirror to align to the alignment tool before the first square + mirror preceding the compressor. + \item Use the second telescope mirror to align to the alignment tool when place between the + square mirrors preceding the compressor. +\end{denumerate} + \clearpage -\section{Six Month Maintenance} +\section{TOPAS-C} % ============================================================================== + +% TODO: figure + +\subsection{Common alignment} % ------------------------------------------------------------------ + +This section discusses common alignment operations that will probably need adjustment on a monthly +basis to ensure ideal OPA behavior. % +All fs table users should feel comfortable performing these tuneups. + +Tips and tricks: +\begin{ditemize} + \item As a rule of thumb, if you don't need light through the poweramp the light should be + blocked to avoid hot spots and damage. The light should be blocked before M8. + \item Use a fluorescent card to visually get a better idea of the centering of the 800 nm beam + through the apertures. + \item Align OPA1 before OPA2. For the sake of consistency, we have agreed that compression should + be adjusted for OPA1 best performance. OPA2 will have to ``live with'' the compression that is + best suited for OPA1. +\end{ditemize} + +\subsubsection{Preparation} + +\begin{denumerate} + \item Ensure that the Spitfire is working (between 3.8 and 4.0 W). + \item Ensure that the pump is not clipping on any mirrors between Spitfire and OPAs. + \item Inspect mode structure of pump for hot spots or diffraction. Clean any dust off of mirrors + between Spitfire and OPAs. + \item Open OPA lid. + \item Set OPA to 1300 nm, ensure motors are homed. +\end{denumerate} + +\subsubsection{Preamp} + +\begin{denumerate} + \item Block pump into poweramp upstream of M8 using block of metal. + \item Open OPA shutter. + \item Ensure that the WL plate is not drilled---look for ``sparking''. This takes an experienced + eye---ask if you have a hard time deciding. If drilled, rotate the WL plate. + \item Ensure that input poynting and compression are good for the preamp by iterating through the + following adjustments. Stop iteration once all metrics are good without further adjustment. + \begin{denumerate} + \item Iteratively align through A0 and A2. The orange-colored white light should go through + A2. + \item Ensure that your poynting changes have not introduced clipping on external mirrors. + \item Ensure that white light is good. + \begin{ditemize} + \item If you are aligning OPA1, adjust compression such that WLG is maximized. Do not + adjust compression to OPA2 WL. + \item Adjust $A_{WL}$ until WL is symmetric and stable. % TODO: figure + \end{ditemize} + \item Ensure that no OPG is present in C1. + \item Manually adjust D1 to maximize seed intensity. + \end{denumerate} + \item Align seed down entire row of holes in-which L6, L7, DM2, NC2, and DM3 lie. Alignment is + accomplished using M5 and M6. + \begin{ditemize} + \item Consider blocking pump into C1 (passing only WL) to ``toggle'' the seed---this helps + distinguish between orange WL and slightly redder seed. + \end{ditemize} +\end{denumerate} + +\subsubsection{Poweramp} + +\begin{denumerate} + \item Unblock pump into poweramp. + \item Setup 407A power meter outside of OPA. + \item Adjust manual D2 until over 600 mW is achieved. + \item Put ``Caution fs OPA free to coldwave'' sign on laser-lab doors. + \item Remove all optics downstream of Mixer 3: filter periscopes (wavelength selectors), + periscope, beam splitter, and beam dump. + \item Iterate the following until optimal power and collinearity are simultaneously reached: + \begin{denumerate} + \item Adjust collinearity of three beams using DM2 + \begin{ditemize} + \item All beams should be overlapped far away. + \item Use surveyor's telescope to observe beams. + \end{ditemize} + \item Maximize 407A-measured power using manual D2. + \item Maximize 407A-measured power using M10. + \end{denumerate} + \item Reassemble optics downstream of Mixer 3. + \item Close OPA lid. + \item Allow a minute for equilibration. + \item Measure and record power---should be over 600 mW. +\end{denumerate} + +\subsection{Full alignment} % -------------------------------------------------------------------- + +The following discussion endeavors to be as complete as possible. % +The goal is to have a procedure the produces a well-aligned OPA regardless of initial +conditions. % +Experienced OPA users may find only pieces of this guide necessary to solve their particular +problem. % + +\subsubsection{Preparation} + +\begin{denumerate} + \item Ensure that the spitfire is working well (between 3.8 and 4.0 W). + \item Ensure that the pump is not clipping on any mirrors between Spitfire and OPA. + \item Inspect mode structure of pump for hot spots or diffraction. Clean any dust off of mirrors + between Spitfire and OPAs. + \item Open OPA lid. + \item Set OPA to 1300 nm, ensure motors are homed. + \item Block pump into poweramp upstream of M8 using block of metal. + \item Block seed between compensating crystal and M5. + \item Remove all side walls from OPA. +\end{denumerate} + +\subsubsection{Input poynting} + +Input poynting is adjusted to ensure good alignment through L1 and L2 into D1. + +\begin{denumerate} + \item Remove A1/L3, VF, $A_{WL}$. + \item Place D2 at nominal position (45 degrees). + \item Using external mirrors, ensure that beam propagates through the alignment tool at the holes + just after L2 and just before M1 (in D1). + \item Ensure that you have not introduced clipping external to the OPA. + \item Ensure that the L1/L2 telescope is outputting a collimated, undistorted beam. +\end{denumerate} + +\subsubsection{D1 alignment} + +\begin{denumerate} + \item If you haven't already, remove A1/L3, VF. + \item Ensure that you are blocking light between compensating crystal and M5. + \item Remove WLG plate, L4, TD, DM1, knife edge. + \item Set C1 to surface normal (should be 0 degrees if affix is set correctly in software.) + \item Using M1 and M2, ensure that beam propagates through the alignment tool at the holes just + after M2 and just before M5. +\end{denumerate} + +\subsubsection{White light} + +\begin{denumerate} + \item Block preamp pump after M3 during this procedure. + \item Remove WL plate if it is present. + \item Replace/adjust AL/L3, adjusting focus to be at white light plate desired position. + \item Replace VF and $A_{WL}$ if they are absent. + \item Replace the WL plate---ensure that the plate is normal to input beam by visual inspection. + \item Optimize WLG using VF, $A_{WL}$, and plate position. + \begin{denumerate} + \item Begin with $A_{WL}$ closed. + \item Open $A_{WL}$ 10\%. + \item Adjust VF to just allow for onset of WLG. + \item Adjust position of sapphire plate to maximize visible component of continuum. + \item Adjust VF to attenuate WLG pump to lowest WLG threshold where central mode and first + outer rings are visible. + \item Adjust compression for WLG symmetry. + \item Continue to open $A_{WL}$ and adjust VS until $A_{WL}$ is as open as possible and VF is + as dark as possible (while maintaining stable WLG). + \end{denumerate} + \item Replace / adjust L4. + \begin{denumerate} + \item Remove DM1 if it is present. + \item Adjust L4 so that the visible component of the WL continuum is focused on A2. This will + ensure that the NIR component focuses at NC1. + \item Ensure that the WL remains centered on the alignment tool / A2. + \begin{ditemize} + \item L4 may be rotated to adjust height. + \end{ditemize} + \item Replace DM1. + \end{denumerate} +\end{denumerate} + +\subsubsection{Preamp pump} + +\begin{denumerate} + \item Remove L5, M4. + \item Adjust M3 to alignment tool holes near edge of OPA to M5 mount. Note that M3 may be rotated + to change height. + \item Ensure that beam is passing through alignment tool near M3. If not, consider translating M3 + or moving BS2. Before making these adjustments ensure that the beam is true into BS2 (see input + poynting section above). + \item Replace L5. Ensure that beam through L5 is on-axis with alignment tool in far field. + \item Replace M4. Point pump so that it intersects with the first red ring in the WL at DM1. + \item Adjust DM1 to spatially overlap pump with WL in NC1. + \item Adjust L5 so pump focus in in C1. If OPG in C1 is seen, back-off L5 by moving towards M3 + until OPG disappears. +\end{denumerate} + +\subsubsection{Seed} + +\begin{denumerate} + \item Ensure that both WL and pump are entering C1 properly. + \item Remove M5 if present. + \item Manually adjust D1 to optimize seed generation. + \item Make fine adjustments to M4 and DM1 to ensure that the seed travels along alignment tools + all the way to the OPA wall. If large adjustments need to be made something upstream must be + wrong. + \item Replace M5. + \item Replace knife edge, if absent. + \begin{ditemize} + \item Ensure you are not clipping the red seed profile. + \end{ditemize} + \item Remove L6 and L7 if present. + \item Use M5 and M6 to align the seed to the alignment guide through C2 and out of the OPA. + \item Replace L6 and L7. +\end{denumerate} + +\subsubsection{Poweramp} + +\begin{denumerate} + \item Ensure that pump is not clipping on BS1, M7. + \item Center pump on M8 using M7. + \item Remove L8 if present. + \item Using M8, M9, alignment tool ensure that pump travels along holes from M9 to M10. + \item Replace L8. + \begin{ditemize} + \item Back of L8 Mount to front of M10 should be $\sim$15 cm. + \end{ditemize} + \item Without clipping, place M11 and point M10 to minimize off-axis angle at M10 (this requires + us to put the pump 1/4 inch right of center as viewed while facing M11). + \item Center pump on M12 using M11. + \item Center pump on DM2 using M12. + \item Overlap with seed in NC2 using DM2. + \item Make small adjustments to M10, DM2 to perfect collinearity and overlap. + \item Adjust manual D2 until over 600 mW is achived. + \item Put ``Caution fs OPA free to coldwave'' sign on laser-lab doors. + \item Remove all optics downstream of Mixer 3: filter periscopes (wavelength selectors), + periscope, beam splitter, and beam dump. + \item Iterate the following until optimal power and collinearity are simultaneously reached: + \begin{denumerate} + \item Adjust collinearity of three beams using DM2 + \begin{ditemize} + \item All beams should be overlapped far away. + \item Use surveyor's telescope to observe beams. + \end{ditemize} + \item Maximize 407A-measured power using manual D2. + \item Maximize 407A-measured power using M10. + \end{denumerate} + \item Reassemble optics downstream of Mixer 3. + \item Close OPA lid. + \item Allow a minute for equilibration. + \item Measure and record power---should be over 600 mW. +\end{denumerate} \clearpage -\section{Tuning MicroHR Monochromator} +\section{MicroHR Monochromator} % ================================================================ Visible Grating. % |