Eligo Omc Installation Plan

Transcript

LASER INTERFEROMETER GRAVITATIONAL WAVE OBSERVATORY - LIGO CALIFORNIA INSTITUTE OF TECHNOLOGY MASSACHUSETTS INSTITUTE OF TECHNOLOGY Engineering Note LIGO-E080024-01-I 2008/01/19 eLIGO OMC Installation plan R Abbott, V Frolov, K Kawabe, S J Waldman California Institute of Technology LIGO Project, MS 18-34 Pasadena, CA 91125 Phone (626) 395-2129 Fax (626) 304-9834 E-mail: [email protected] Massachusetts Institute of Technology LIGO Project, Room NW22-295 Cambridge, MA 02139 Phone (617) 253-4824 Fax (617) 253-7014 E-mail: [email protected] LIGO Hanford Observatory Route 10, Mile Marker 2 Richland, WA 99352 Phone (509) 372-8106 Fax (509) 372-8137 E-mail: [email protected] LIGO Livingston Observatory 19100 LIGO Lane Livingston, LA 70754 Phone (225) 686-3100 Fax (225) 686-7189 E-mail: [email protected] http://www.ligo.caltech.edu/ LIGO-E080024-01-I 1 Introduction The eLIGO OMC installation procedure requires many steps that must be carried out sequentially but not necessarily at one time. To best match the assumed time and man power constraints, this document is arranged in sections with each section devoted to a single task. Each section has a requirements, associated documents, and detailed procedure. The major sections are: §2 testing of the OMC electronics and software; §3 integration and alignment of the OMC mounted hardware; §4 integration of the OMC with the suspension; §5 HAM6 installation; and §6 ISCT6 installation. page 1 LIGO-E080024-01-I 2 Electronics verification 2.1 Requirements 2.1.1 2 2 2 2 2 2.1.2 2 2 2 2 2.1.3 Class A Hardware DCPD amplifiers (2x) DCPD and radiators (2x) In vacuum QPD (4x) OTAS and PZT on OMC In-vacuum cabling harnesses (3x) Class B Hardware Mirror cables (fake vacuum feed-thrus) Laser pointer Clean room area by HAM6 Table by HAM6 Dirty Hardware and Electronics 2 TPT and OMS computers 2 Cabling to HAM6 2 CDS computer by HAM6 2.2 Related documents • • • • • • • • • 2.3 D060283-B1: OMC High Voltage Piezo Driver Board schematics D070117-C: OMC Heater Driver Board schematics D070263-A1: OMC Quadrant Photodetector Whitening Board schematics D070281-B1: OMC DCPD Whitening Board schematics D070536-A: OMC Wiring Detailed Diagrams D060572-B1: OMC In-vacuum DCPD schematics D070261-B4: OMC Block Diagram D070157-00 QPD Mounting Plate and Connector D070131-00 DCPD Connector OMC Detailed procedure 1. Check cabling of TPT outputs to HAM6 (a) Energize high voltage (b) Measure voltage at PZT satellite box and step PZT control (c) Measure voltage at OTAS heater satellite and step OTAS control 2. Check cabling of TPT inputs from HAM6 (a) Connect cables from TPT to satellite boxes page 2 LIGO-E080024-01-I (b) Connect cables from satellite boxes to mirror cables and in-vacuum cabling (c) “Beep” cables to confirm connections to satellite boxes (d) QPD: Connect 4 QPDs to 4 QPD in vacuum cables (two for OMC, two for tip/tilts) (e) QPD: Use laser pointer to illuminate each quadrant individually and confirm response on CDS computer (f) DCPD: After double checking polarity of DCPD cables and connections, deenergize satellite box and cable in-vacuum harness to DCPD pre-amps (x2) and DCPD pre-amps to DCPDs (x2). After double-checking everything again, energize the satellite box so that the DCPDs are active. (g) DCPD: Illuminate each DCPD with the laser pointer and confirm response on CDS computer (h) DCPD: With DCPD under constant illumination, switch trans-impedance and confirm response. (i) PZT: De-energize HV supply and confirm polarity of connection AT PZT. Note that PZT is connected to OMC with negative terminal oriented towards the mirror. The PZT terminal bonded to the tombstone is the positive terminal. (j) PZT: After confirming PZT polarity, energize PZT high voltage. (k) PZT: Drive PZT at 8 kHz, xxx cts peak to peak through the dither path, and confirm an audible PZT response. Later we will confirm the PZT transfer function and test the installed high frequency response. (l) OTAS: Zero the OTAS control signal and plug in the OTAS (make sure there is no control signal). Again, note that the OTAS is connected to the OMC and is very delicate. Be Careful! (m) OTAS: The OTAS read-back should read room temperature. Drive with a +10,000 count step and confirm temperature response of OTAS. This will be tested more reliably later. 3. Measure DCPD Quantum Efficiency (a) With a known load resistor, bias PD and illuminate with 1064nm light. (b) Measure voltage through laod and measure incident power with power meter. (c) Repeat (or perform instead) procedure with DCPD preamp and amplified load resisitor. This section tests the front ends, frame builder, software, cabling and electronics for the OMC specific electronics. The remaining procedures assume that all of the electronics have tested valid. Although there is some overlap with the SUS and Tip/Tilt electronics (ie. QPDs), the testing for those systems is assumed to be done separately. page 3 LIGO-E080024-01-I 3 OMC integration 3.1 Requirements This task assumes the electronics, software and cables have been verified as discussed in §2. 3.1.1 2 2 2 2 2 2 2 3.1.2 Class A Hardware OMC in frame DCPD preamp and mounting hardware (2x) DCPDs, radiators and hardware (2x) PZT connector block OMC-DCPD wiring harness OMC-aux wiring harness QPDs and mounting hardware (2x) Class B hardware 2 Allen wrench for 2mm socket cap 2 Translation stage + QPD adapter 2 IR card with good holes in it 3.1.3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 Dirty Hardware & 500 mW NPRO & 5 m 1064 nm fiber (maybe 50m for use in HAM6) Fiber launch with C230TM lens (2x for input and output) EO modulator on new focus stage 1 inch steering mirrors, mounts, and posts (at least 6) f = xxxx mm biconvex lens (TBD by mode matching to fiber) Polarizing beam splitter cube Power meter Beam dumps (a few) Neutral density filter (optional) Thorlabs (or equivalent) RF photodiode Thorlabs DC photodiode IR sensitive CCD camera and mounting post with ball head Macro lens for CCD camera Light shield for CCD camera and mounting post page 4 LIGO-E080024-01-I 3.1.4 2 2 2 2 2 2 2 2 2 2 Electronics RF mixer RF function generator RF splitter BNC cables RF attenuators Monitor for CCD. Thorlabs 150 V amplifier SR560 preamplifier (a couple) Oscilloscope Differential to single-ended converter The fiber is not strictly necessary. Its purpose is to ease the coupling into the OMC such that we can measure ≥ 95% mode matching and confirm the cavity Finesse and absorption measurements before placing the OMC in vacuum. I (SJW) believe mode-matching the beam from the NPRO and EO will be more difficult in practice and the fiber is worth the effort. 3.2 Related documents 3.3 Detailed procedure The purpose of the OMC integration is two-fold. First, the DCPDs, DCPD pre-amps, QPDs, PZT and OTAS must be connected and aligned as necessary. Second, the OMC performance must be documented before we place it into vacuum. The photo-diode alignment requires a resonating OMC, hence the requirement of an aligned, mode-matched NPRO. The following procedure is organized accordingly. 3.3.1 Assembly 1. Fiber couple NPRO (a) Mount vertically polarized NPRO to table at a reasonable height on table or breadboard (b) Mount EO a few cm in front of NPRO right side up (c) Mount two steering mirrors before the fiber coupler, all the right height. (d) Get light into the fiber and maximize the through put. (e) Attenuate if desired 2. Lock Cavity (a) Mount OMC (in frame) to optical table “light side up.” OMC should be towards a corner of the table such that both DCPDs are easily accessible. (b) Mount fiber output coupler to table XXX inches from OMC SM1 taking into account 3 90 degree steering mirrors page 5 LIGO-E080024-01-I (c) Mount 3 steering mirrors and lens such that distances are: OMC SM1 to lens = xxx inches, lens to fiber launch = xxx inches. Use z-axis of fiber output coupler to make spot at lens ≈ xx cm. Leave clearance for QPD adjustment stages. (d) Steer input mirrors so that beam hits center of OMC M1 and OMC M2 using an IR card (e) At this point, the beam should travel around the OMC back to M1 to M2 to M3 to M4 to M1. If not, adjust steering mirrors until it does. (f) Once the beam round trips the OMC, there should be flashes in transmission. Align the camera, light shield and thorlabs DC photodiode to the OMC transmited beams (as split by the OMC output beam splitter). (g) Use a steering mirror to direct the OMC reflected beam onto the Thorlabs RF photodiode. Center the beam using the PD DC signal. (h) Connect the Thorlabs HV to the fast channel input of the NPRO (make sure there is an HV compatible NPRO available). Control the Thorlabs with a 0-10 V signal from CDS. Ideally, this is from a differential to single ended driver, but if necessary it can be single side of the differential (with 1/2 the gain). (i) Sweep NPRO frequency and see fringes and rough maximize the TM00 peak (j) Connect RF PD to mixer, RF low pass filter, and SR560 with 100 kHz low pass 6 dB/octave low pass. Phase the RF signal with lengths of BNC until there is a reasonable zero-crossing error signal. (k) Calibrate error signal using expected PDH shape for the RF frequency and cavity length (l) If available, connect control signal to NPRO slow path. (m) Digitize the RF error signal and close the loop (n) Maximize the TM00 transmission. (o) Move Thorlabs DCPD to sense OMC REFL, maybe reflected off the RF diode. 3. Mount QPDs (a) Position translation stage + QPD adaptor for use with near field QPD (b) Mount QPD and adjust transverse position to zero error signal. Confirm that QPD sign and quadrants are correct. (c) Move translation stage to Far field and repeat. 4. Mount DCPD premps (a) With OMC in light-side-up orientation bolted to the table in a frame, mount the two DCPD preamps to the dark side, signal side to breadboard center. 5. Mount DCPDs (a) Orient camera with Macro lens so it has a view of the REFL DCPD face. This might be difficult because of beam dump location. (Drat). page 6 LIGO-E080024-01-I (b) Mount electrically connected DCPD+radiator to tombstone using threaded adaptor plate (c) With OMC locked, translate DCPD by hand so the beam is centered on the PD. (Note that glass should be removed from photodiode by this stage) (d) Re-orient camera for TRANS DCPD, attach PD and radiator, and repeat alignment. 6. Measure DCPD QE (a) If you haven’t already, measure the incident light and compare with the DCPD signal. Get the errors down to a few percent. 7. Connect electronics (a) Connect DCPDs to satellite box via mirror cable (b) Ditto QPDs (c) Ditto OTAS (d) Ditto PZT (The dark side cable routing does not need to be perfect at this point). 3.3.2 Verification 1. Actuator performance (a) With laser locked to OMC, measure loop transfer function from 10 Hz to 10 kHz. (b) Buzz PZT to Nyquist frequency and measure PDH error point response (correct for loop) using dither path. Compare with XXXXXX. (c) Repeat using LSC path and compare with XXXXXX. Calibrate using PDH calibration and confirm 1 nm/V type gain. (d) Put a full scale step into OTAS and measure time constant, thermal response, and laser frequency response (look in control signal). 2. Detector performance (a) Adjust input alignment and confirm QPD signal. Rough calibrate QPD error signals using DC cavity transmission confirm it makes sense. (b) Tune input beam onto each quadrant in turn and set DC gains. (8 quadrants) (c) Measure power into QPD and make sure the DC gains make sense. (d) Measure DCPD DC gain. If they are more than a few percent different, investigate at great length. Measure the power incident on each DCPD and make sure it, and the associated shot noise, make sense. (e) Sweep OMC PZT and measure DCPD response (both AC and DC) out to Nyquist frequency. (f) By comparing the DCPD amplitude modulation to the reflected PD DC error signal, measure the DCPD whitening and build filters. Compare the PZT response as measured by the PDH signal and the DCPD and make sure they agree. page 7 LIGO-E080024-01-I 3. Optical performance (a) Measure Finesse. The cavity decay time may be long enough to do this using a fast shutter and the cavity decay time. Else, guesstimate it from the PDH or PZT calibrations. Using the PZT calibration from Caltech (1.1 nm/V) we can dead reckon the finesse. (b) Measure cavity absorption by comparing the mode matching, input power, and transmitted power. (c) Measure the g-factor, if you can figure out how. (d) Measure each individual photo-diodes quantum efficiency. 4. Dither lock (a) Instead of locking the laser to the OMC, dither lock the OMC to the laser in preparation for the work in HAM6. Use only OMC mounted detectors and feedback for locking. page 8 LIGO-E080024-01-I 4 SUS integration 4.1 Requirements 4.1.1 Class A Hardware 2 Assembled OMC 2 Assembled suspension 4.1.2 Class B Hardware 2 Installation lab jacks 2 Tools 4.1.3 Dirty Hardware 2 HeNe or laser pointer for use in levelling operation 4.1.4 Electronics 2 CDS workstation Note that this procedure assumes the suspension electronics and mechanics have already been checked with a metal bench. 4.2 Related documents • Blah 4.3 Detailed procedure 1. Prepare SUS (a) Prep SUS to remove metal bench and remove metal bench (b) Remove OSEMs and earthquake stops (c) Position lab jacks to take OMC and frame 2. Prepare OMC (a) Remove optics from table (b) Turn OMC dark side up and dress DCPD and Aux cables for installation 3. Hang OMC (a) Put OMC dark side up on lab jacks, jack the jacks, and put OMC on wires (b) Install earthquake stops with few mm clearance page 9 LIGO-E080024-01-I (c) Remove lab jacks and OMC frame (d) Connect OMC cables to SUS frame (e) Follow SUS procedure to balance OMC (f) Install and center OSEMs 4. Verify positioning (a) Confirm by touch that intermediate mass is free in all DOFs and the OMC is clear of earthquake stops (b) Buzz all OSEM DOFs and make sure the transfer functions and free-hangingness are OK page 10 LIGO-E080024-01-I 5 HAM6 build 5.1 Requirements 5.1.1 2 2 2 2 2 2 2 2 5.1.2 Class A Hardware Integrate OMC and SUS and cables Tip/Tilt system and cables (2x) QPDs and cables (2x) 2 inch fixed optic holder and post Standard table top beam dump and mounting hardware (6x) DCPD table top beam dump and mounting hardware (1x) Table-side viewport beam dumps (2x) 1 inch 90 degree steering mirrors (4x) Class B hardware 2 Tools 2 IR card 2 Laser pointer 5.1.3 Dirty hardware 5.1.4 Electronics 2 CDS workstation The HAM6 integration procedure requires well-aligned light from the IFO. This can be single arm lock, bright Michelson, or single bounce misaligned. Only ' 10 mW are necessary but more are welcome up to the OMC damage thresholds. 5.2 Related documents • • • • • • • D080004-00 D080003-00 D070258-00 D070155-00 D070150-00 D070143-00 D070142-00 D-SUB ”L” Bracket Isolation Adapter Tip/Tilt D-SUB Bracket Pedestal Mount for Optic or Quadrant Photo Diode OMC Graveyard Wire Loom DCPD Radiator Wire Clamp DCPD Radiator Retainer Ring DCPD Mounting Washer page 11 LIGO-E080024-01-I 5.3 Detailed Procedure 1. Lock down earthquake stops and position OMC&SUS on HAM6 table. Connect all appropriate cables via vacuum feed-thrus and spot check everything. 2. CONFIRM clearance of AS port beam under OMC! If the alignment is bad, figure out a way around it. Maybe tilt HEPI? 3. Place DCPD beam dump, fixed 2 inch optic, and OMC REFL prompt ghost beam dump inside SUS structure on table with rough alignments 4. Align Tip/Tilts in their appropriate positions so the IFO beam is centered on each mirror. 5. Use IR card and OMC QPDs to get beam aligned to OMC using tip-tilt DC alignment. If necessary, shift Tip/Tilts to center beam on optics and relieve DC offsets. 6. Lock OMC to IFO output beam and celebrate! If it doesn’t work, get back to work. 7. Confirm beam dumping of DCPD beam, alignment of fixed 2 inch mount and dumping of OMC REFL prompt ghost 8. Place steering mirrors for OMC REFL and OMC pickoff to extract beams through viewports. 9. Place beam dumps for mirror leak fields and OMC REFL secondary ghost. 10. Hang table side viewport beam dumps. 11. Celebrate again. page 12 LIGO-E080024-01-I 6 ISCT6 build 6.1 Requirements 2 2 2 2 2 2 2 2 Viewport periscopes and optics (2x) Thorlabs DC photodiode (1x) Thorlabs RF photodiode (1x) for PDH loop investigation 2 inch 50/50 beam splitter Optional beam splitter for PD power level high quality beam dump for OMC REFL beam GIG-E camera Absorptive ND filters Since ITM6 is not in vacuum, there are no cleanliness requirements beyond good optics practice. 6.2 Related documents 2 Table layout 6.3 Detailed procedure 1. Find the OMC REFL beam exiting HAM6 viewport and position periscope appropriately 2. Align (optional) beam splitter, (optional) beam dump, second beam splitter, and DC and RF photodiodes as indicated in diagram 3. Find the OMC pickoff beam exiting HAM 6 viewport and position second periscope 4. Align camera to pickoff beam and attenuate beam as necessary with neutral density filters page 13