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Droplet SP2 Manual

Single particle soot photometer
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SP2
Single Particle Soot
Photometer
Laser Alignment Manual
DOC-0229 Rev. E
2400 Trade Centre Avenue
Longmont, CO 80503 USA
A L L R I G H T S R E S E R V E D

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  • Page 1 Single Particle Soot Photometer Laser Alignment Manual DOC-0229 Rev. E 2400 Trade Centre Avenue Longmont, CO 80503 USA A L L R I G H T S R E S E R V E D...
  • Page 2 General Information In no event will Droplet Measurement Technologies, LLC (DMT) be liable for direct, indirect, special, incidental or consequential damages resulting from any defect or omissions in this manual. DMT reserves the right to make changes to this manual and the products it describes at any time, without notice or obligation.

  • Page 3: Table Of Contents

    Step-by-Step Instructions for a major alignment ................ 20 Appendix A: Tools and Replacement Items from DMT ............37 Appendix B: SP2 YAG Pump Laser Storage & Handling Instructions ........37 Storing the SP2 YAG Pump Laser ......................37 Handling the SP2 YAG Laser ........................37 Appendix C: Revisions to Manual ..................
  • Page 4 Figure 33: Locking and Adjustment Screws ................35 Figure 34: Centered chamber (coplanar slide plate and slide rail end faces) ......36 Figure 35: SP2 Pump Laser in Protective Box ................ 37 Figure 36: Shorting Plug Detached (left) and Attached (right) to Power Connector ....38 Figure 37: Protective Cap SMA Fiber Connector;...

  • Page 5: Introduction: Laser Cavity Performance

    Introduction: Laser Cavity Performance Figure 1 shows a schematic depiction of the pumped Nd:YAG plano-concave laser resonator at the heart of the SP2 spectrometer head. Particles in the aerosol jet intersect the laser beam within the resonator cavity. Figure 1: Nd: YAG Laser Resonator Cavity...

  • Page 6: Sequence Of Laser Cavity Troubleshooting

    Clean surface of output coupler Loss of power Contamination or degradation of o Replace output coupler optical component surfaces o Replace YAG crystal Table 1: Causes and Remedies of Symptoms of Degraded Performance DOC-0229 Rev E © 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC...

  • Page 7: Figure 2: Troubleshooting Sequence

    SP2 Laser Alignment Manual Figure 2 presents the recommended troubleshooting sequence for restoration of lost power. Difficulty and cost increase as the sequence progresses. Figure 2: Troubleshooting Sequence DOC-0229 Rev E © 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC...

  • Page 8: Minor Alignment Process (First Option)

    Noteworthy components of the SP2 spectrometer head are identified in Figure 3. Figure 3: SP2 Spectrometer Head Minor Alignment Process (First Option) These are adjustments that can be made without removal of core optical components. A minor alignment adjustment of the Output Coupler or Mode Aperture, without removal of the spectrometer DOC-0229 Rev E ©...

  • Page 9: Equipment

    SP2 mode aperture alignment tool 1.2 Step-by-Step Instructions for a minor alignment Run the SP2 for 15-30 minutes with a filter on the inlet to remove as many particles as possible from the instrument. (Leave the filter in place until step 28) is reached.) With the laser operational, record the YAG power voltage reported in the SP2 software.

  • Page 10: Figure 4: Mode Aperture Removal

    If the laser power does not increase by more than 10%, it is recommended that the beam mode be evaluated also to insure the laser is in optimum operating condition. This will be checked in the following steps. DOC-0229 Rev E © 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC...

  • Page 11: Figure 5: Installing Mode Aperture In Upside-Down Position

    It may be necessary to remove the right-side panel from the SP2 to access the screws on the laser power monitor. The reference to the right side of the SP2 is as viewed from the front of the instrument.

  • Page 12: Figure 6: Satisfactory Beam Profile

    13). Figure 6: Satisfactory Beam Profile Figure 7: Undesired Higher Mode Turn off the laser current, and then the flow system. Wait 1-2 minutes for all flow to stop before continuing. DOC-0229 Rev E © 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC...

  • Page 13: Figure 8: Coupler Chamber Sealing Screws

    Figure 9 illustrates the drivers properly engaged. (Two walls have been removed in this figure to improve the view). For SP2 instruments with serial numbers less than 020, the drivers must be inserted at a slight angle to contact the adjustment screws (Figure 10).
  • Page 14 Otherwise, continue with the following steps to adjust the mode aperture position. If the right-side panel has not been removed from the SP2 chassis, remove it at this time. Loosen the four holding screws in the mode aperture block very slightly. The block should move when moderate side force is applied but be not so loose that the O-ring behind the block is not in good contact with the YAG crystal chamber.

  • Page 15: Figure 11: Attachment Of Mode Aperture Alignment Tool

    SP2 Laser Alignment Manual Figure 11: Attachment of Mode Aperture Alignment Tool Figure 12: Manual mode aperture alignment DOC-0229 Rev E © 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC...

  • Page 16: Figure 13: Application Of Extra Force To Assist Stage Springs

    0.27-micron PSL particles at a nominal concentration of 300/cc. Remove the filter from the SP2 sample inlet and connect the particle stream to the inlet. After the concentration has stabilized, record data for 20,000 particles. Record the position of the chamber as given by the micrometer along with the data file numbers.

  • Page 17: Figure 14: Histogram Response As Chamber Plate Is Translated

    Tighten the chamber locking screws, and, if system performance has been restored, reinstall the side and top panels on the SP2 chassis. Figure 14: Histogram Response as Chamber Plate is Translated DOC-0229 Rev E ©...

  • Page 18: Major Alignment Process (Second Option)

    SP2 will be restored by following this section only once. With practice, this process can be completed in about three hours, but will typically take much longer for newer users.

  • Page 19: Dangers Of Esd Shock

    ESD shock. It is a good practice to wear a ground strap, and/or other means of ESD protection, while working inside the SP2. The detector boards are especially sensitive, and care must be taken when handling and removing the detector chamber, particularly when the detectors are unplugged.

  • Page 20: Step-By-Step Instructions For A Major Alignment

    Disconnect the exhaust flow connection at the base of the detector chamber on the left side. If you have an older SP2, disconnect the line to the pressure transducer from the left side of the chamber. Remove the Sheath flow connection from the side of the sample jet assembly.

  • Page 21: Figure 16: Unscrewing Sma Connector

    The laser frame is secured to the chassis by four screws that fit through the U-shaped support into the bottom of the laser frame. On some SP2 instruments the fasteners are hex head bolts, and it will be necessary to reach through the U supports and unscrew the bolts. Newer instruments have a hole through the base of the instrument to access the hex drive socket head screw.

  • Page 22: Figure 18: Assembled Sp2 Alignment Fixture

    Figure 18: Assembled SP2 Alignment Fixture Figure 19: Frame-to-fixture fasteners The chamber must be removed from the laser frame for the alignment process. On older instruments, you must loosen the four 4-40 Allen drive socket head cap screws from the inlet jet and remove the inlet jet from the chamber to get the chamber out of the frame.

  • Page 23: Figure 20: Removing Output Coupler Mounting Screws

    Figure 20: Removing Output Coupler Mounting Screws Note about SP2 Optical Cleaning: In all cases, where there is contamination believed to be present, the optical surface should be blown off using clean compressed air, before surface cleaning is attempted.

  • Page 24: Figure 21: Wiping The Output Coupler

    If this is the case, another pass, with a new folded set of wipers, should be done. Figure 21: Wiping the output coupler DOC-0229 Rev E © 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC...

  • Page 25: Figure 22: Yag Crystal And Optical Pump Assembly

    YAG assembly; when the assembly is lifted, make sure this spring is captured. Figure 22 shows a complete YAG crystal and optical pump assembly removed from the SP2. Figure 22: YAG Crystal and Optical Pump Assembly DOC-0229 Rev E ©...

  • Page 26: Figure 23: Fasteners Securing Yag Crystal Holder To Pump Base

    TMA. On newer SP2s it is not necessary to remove the TMA, because the crystal holder screws are on the bottom, and you should skip to step 26), if this applies to your SP2. DOC-0229 Rev E...

  • Page 27: Figure 24: Three Fasteners Secure Tma To Yag Crystal Holder

    Thermo-Electric-Cooler (TEC) before removing, because if the TEC is put back in upside down, a thermal runaway condition will result when the SP2 software attempts to regulate the crystal temperature. The unit must be handled carefully as the parts will be attached at the connector.

  • Page 28: Figure 26: Yag Crystal Cushioned In Holder

    Set this assembly aside. To inspect the Mode Match Optics, loosen the setscrew holding the Mode Match Optics barrel in place and slide the barrel out of the vertical bracket of the YAG base. DOC-0229 Rev E © 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC...
  • Page 29 A fiber cap may be used if available. Now, all of the core optical components should be clean, and ready for reinstallation and initial alignment on the SP2 alignment fixture. Ensure the pump block filter has been removed (this should have happened in step 13).) Insert the MP-0722 pinhole into the pump block location.

  • Page 30: Figure 27: Alignment Beam Centered On Pinholes

    Reinstall the two #8 horizontal locking screws into the base of the YAG assembly. Tighten them all the way down to fully seat the assembly onto the locating pin, then loosen them by about ¼ of a turn. DOC-0229 Rev E © 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC...

  • Page 31: Figure 28: Paper Between Crystal And Mode Match Optics

    Figure 29 details the YAG crystal assembly for the SP2 and the adjustment and locking screws, NOTE: The thermal management system is removed from (Figure 29) for clarity The adjustments provide for rotation and tip of the YAG crystal to align it on the optical axis.

  • Page 32: Figure 30: Beam And Reflection Coincidence

    Remove the piece of paper blocking the mode match optics. Place it somewhere between the crystal chamber and the coupler chamber to keep the reflection from the crystal and mode match optics from interfering with the coupler alignment. DOC-0229 Rev E © 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC...

  • Page 33: Figure 31: Paper Placed To Block Reflection From Crystal Face

    The laser frame can now be removed from the alignment bench and returned to the SP2 chassis. Put all four of the screws into the bottom to secure the laser frame into the SP2 chassis and tighten them. The fiber from the pump laser needs to be connected to the YAG crystal assembly;...

  • Page 34: Figure 32: Light Concentric Around Entrance To Coupler Chamber

    Blue color to the laser light, but the light is actually Red/Infra-Red. This image was taken with an Infra-Red sensitive camera. Turn off the SP2 laser. If the laser light was already centered on the hole in the coupler chamber in the previous step, then skip to Step 62).

  • Page 35: Figure 33: Locking And Adjustment Screws

    Tighten the setscrew well, once you have the barrel in the best position. Turn off the laser and close the SP2 software. Shut down the SP2 power. DOC-0229 Rev E...

  • Page 36: Figure 34: Centered Chamber (Coplanar Slide Plate And Slide Rail End Faces)

    Figure 34: Centered chamber (coplanar slide plate and slide rail end faces) Start the SP2 system and software, place a filter on the sample inlet and turn on the sample pump. Note: If the sample flow immediately goes to a reading of about -50 vccm, then something has been left open, or unsealed.

  • Page 37: Appendix A: Tools And Replacement Items From Dmt

    SP2 Laser Alignment Manual Appendix A: Tools and Replacement Items from DMT DMT sells several kits to aid users in their SP2 laser-alignment efforts. These kits include the following types of items: • Absorbond wipers • Beam scan camera assembly •...

  • Page 38: Figure 36: Shorting Plug Detached (Left) And Attached (Right) To Power Connector

    3. The minimum bend radius of the fiber is 6 cm. Bending the fiber at a smaller radius can break the glass fiber inside the sheath. If the fiber is broken, the laser will need to be returned to Droplet Measurement for repair.

  • Page 39: Appendix C: Revisions To Manual

    Rearranged steps in alignment procedure so they are in 4.38-4.40 chronological order 7-28-14 Corrected instructions in step 4.53. 7/1/17 Updates and corrections (various) 03/7/18 Correct callout Ultra Torr, add caution for sealed nut DOC-0229 Rev E © 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC...

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