ThermoMicroscopes Aurora-2, User Manual

Page 1: ...ThermoMicroscopes 85 10316 Rev A ThermoMicroscopes 1171 Borregas Avenue Sunnyvale California 94089 Tel 408 747 1600 Fax 408 747 1601 Aurora 2 User s Manual ...

Page 2: ...t into another program for your use on the single machine Any portion of the pro gram merged into another program will continue to be subject to the terms of this Agreement You must reproduce and include the copyright notice on any copy modification or portion merged into another program Transfer the program and license to another party within your organization if the party agrees to accept the te...

Page 3: ...Set Up Instrument Overview 2 1 Aurora 2 Package 2 3 Standard Components 2 3 Optional Equipment 2 4 Installation 2 4 Instrument Location Considerations 2 4 Cable Connections 2 5 Powering Up the System 2 5 The Aurora 2 Head 2 8 Placing the Head on the Stage 2 10 Removing the Head 2 11 Mounting the Sample on the Stage 2 11 Installing a Probe 2 11 Aurora Control Unit 2 15 Optics Controls 2 16 Transmis...

Page 4: ...ing the Resonant Drive Frequency 3 2 Moving the Tip into Feedback 3 3 Taking a Topography Scan 3 5 Optimizing the P I D Settings 3 5 Ending a Topography Session 3 7 Chapter 4 Taking an NSOM Scan Checking Feedback Parameters 4 1 Approaching the Sample and Taking a Scan 4 2 Ending an NSOM Session 4 3 Chapter 5 Counter Board Operation Introduction 5 1 Hardware Set Up 5 1 Counter Set Up 5 2 TTL Out 5 ...

Page 5: ...nalysis It is important to read this manual and be familiar with the Aurora 2 instrument to facilitate more productive and efficient use of NSOM as a research tool ABOUT THIS MANUAL Chapter 1 provides an overview of the theory of NSOM and how it is applied in the Aurora 2 instrument Chapter 2 describes the Aurora 2 instrument components and set up Chapters 3 and 4 provide step by step instructions...

Page 6: ...d a warning until the conditions of the warning are under stood and met Caution statements indicated by this symbol call attention to possible damage to the system or to the impairment of safety unless procedures described in this manual are followed exactly WARNING NEVER LOOK DIRECTLY INTO THE LASER BEAM These labels are placed on the Aurora 2 to warn you of the danger of laser light Exposure to ...

Page 7: ... safe working space around the products for servicing by ThermoMicroscopes personnel REPAIRS AND REPLACEMENTS ThermoMicroscopes will at its option either repair or replace defective instruments or parts Repair or replacement of products or parts under warranty does not extend the original warranty period With the exception of consumable and maintenance items re placement parts or products used on ...

Page 8: ... been modified or altered without written authorization from ThermoMicroscopes f Products which have had the serial number altered or removed g Improper or inadequate care maintenance adjustment or calibration by the user ...

Page 9: ... the development of scanning probe microscopes however that technology existed to maintain such close tip sample spacing while a tip was being scanned over a sample NSOM TIPS The light source in an NSOM system is launched into an optical fiber The end of the fiber is pulled down to a diameter of 50 nm The fiber is then coated with aluminum approx imately 100 nm thick The fiber becomes a light funn...

Page 10: ...y This vibration is parallel to the surface As the tip approaches the surface the vibration amplitude and phase change This change in amplitude and phase generates an electrical signal that is input into the feedback loop The Aurora 2 uses the tuning fork mechanism for distance control as it has the advantage of producing an electrical signal directly rather than relying on another device to gener...

Page 11: ...alone The NSOM used as an optical microscope can be operated either in tip collection or tip illumination mode In tip collection mode the sample is the light source and the tip acts as a way to collect this light This method is best for samples such as waveguides and laser diodes Tip illumination mode is perhaps the most common NSOM mode Tip illumination uses the tip as a light funnel to illuminat...

Page 12: ...al modes Figure 1 4 NSOM Operational Modes Examples of NSOM imaging with the Aurora using the modes referenced in Figure 1 4 are included in the following literature 1 P J Moyer T Cloninger J Gole and L Bottomley Experimental evidence for molecule like absorption and emission of porous silicon using near field and far field optical spectroscopy Phys Rev B 60 No 7 4889 4896 1999 2 P F Barbara D M A...

Page 13: ...n the removable Aurora 2 micro scope head and positioned above the sample Topographic and optical images can be taken simultaneously Figure 2 1 Topography Feedback Loop The optical components of the Aurora 2 system are used for taking NSOM data as well as for focusing the optics and monitoring the probe sample approach The rotating mirror see Figure 2 2 selects either the reflection or transmissio...

Page 14: ...ube PMT CCD camera Flipper mirrors Focusing lenses Reflection objective lens Transmission objective lens Stage Rotating mirror Optional Hardware Head CCD Camera Reflection tower PMT flipper Camera flipper mirror hidden mirror Cam splicer PMT Reflection objective Scanning Transmission objective stage ...

Page 15: ...tripper tool Tool kit Cables NSOM standard sample User s Manual Instrument enclosure SPMLab software SPMLab Software Reference Manual OPTIONAL EQUIPMENT I O U input output board I O P photon counter board Laser Laser coupler Daughter board for additional analog to digital conversion channels Explorer SPM head Vibration isolation table The Explorer SPM head is a popular option as it uses the same c...

Page 16: ...he upper floors Temperature and humidity should be controlled to maintain constant en vironmental conditions Normal indoor conditions i e room temperature and average humidity are sufficient Extremes of temperature and humidity will negatively affect the instrument and possibly cause damage CABLE CONNECTIONS CAUTION Make sure the power is OFF to all the modules and the computer while setting up Co...

Page 17: ...oltage is turned all the way down to the counter clockwise limit before powering up the components Once all the connections are made the components can be powered up First turn on the ECU Plus then the computer and the video monitor The ECU Plus should always be turned on before the computer so that the ECU interface is recognized and initialized The laser is powered up separately Power is automat...

Page 18: ...tor Rear Panel IN OUT DSP Computer Aurora 2 Stage Rear Panel Aurora 2 Control Unit Rear panel ACU CABLE 1 CABLE 2 BNC 1 BNC 2 BNC 3 BNC 4 TO STAGE TO ECU TO STAGE MOD IN NSOM IN MOD OUT NSOM OUT VIDEO OUT OUT 1 OUT 2 OUT 3 OUT 4 SPARE EFM DRIVE DRIVE A DRIVE B SIGNAL IN A SIGNAL IN B I O M O D I O 1 0 I O U I O P Optional ...

Page 19: ... Panel ACU CABLE 1 CABLE 2 BNC 1 BNC 2 BNC 3 BNC 4 Aurora 2 Control Unit Rear panel TO STAGE TO ECU TO STAGE MOD IN NSOM IN MOD OUT NSOM OUT VIDEO OUT ECU Plus Rear panel OUT 1 OUT 2 IN 1 IN 2 CPU POWER STAGE STAGE 2 MODULE OUT 1 OUT 2 OUT 3 OUT 4 SPARE EFM DRIVE DRIVE A DRIVE B SIGNAL IN A SIGNAL IN B I O M O D I O 1 0 X OSCILLATOR OUT or SINE OUT INPUT A Lock In Amplifier I O U I O P ...

Page 20: ...umbscrews watch the image on the video monitor to make sure the probe does not crash into the sample or stage Figure 2 7 Aurora 2 Head The Aurora 2 head rests on a kinematic mount on the instrument base as shown in Figure 2 8 note that there is also a kinematic mount for the Explorer head The Z height between the probe and the sample stage is controlled by the three Z height screws as shown in Fig...

Page 21: ...OVERVIEW SET UP 2 9 Aurora 2 User s Manual Figure 2 8 Kinematic Mount Figure 2 9 Z Height Screws Aurora 2 kinematic mount Scanning stage Reflection objective Motorized screw Manual screws mount first mount first ...

Page 22: ...ning stage before lowering the head all the way onto the mount If necessary adjust the thumbscrews so the head does not end up resting on the stage instead of the kinematic mount Step 5 Lower the head slowly onto the kinematic mount tilting it slightly away from you so the manual Z height screw opposite you lowers into the mount first as shown in Figure 2 10 Figure 2 10 Placing the Head on the Sta...

Page 23: ...made by coating a surface with latex spheres approximately 450 nm in diameter then depositing aluminum onto the surface The spheres are then removed leaving the coating on the interstitial areas as shown in Figure 2 11 Figure 2 11 Standard Sample Example CAUTION To avoid damage to the piezo scanners do not apply more force than nec essary to the scanning stage To mount the sample you must remove t...

Page 24: ...am lining of the probe box until the tool snaps into place Step 3 Carefully pull the tape off the optical fiber so the probe can be removed from the box Unroll the fiber taking care not to touch the tuning fork or put any strain on the fiber Step 4 Slide the probe into the holder in the head by sliding it under the clips as shown in Figure 2 13 Step 5 Make sure the three clips make contact with th...

Page 25: ...AURORA 2 OVERVIEW SET UP 2 13 Aurora 2 User s Manual Figure 2 13 Sliding the Probe into the Holder Figure 2 14 Probe Cartridge Probe Contact Clips Gold Contact Pads Piezo Tuning Fork and Fiber ...

Page 26: ... of the tip fiber Note that once stripped the fiber is very brittle Step 10 Use the optical fiber cleaver from the tool kit to cleave the end of the tip fiber a Open the jaws of the cleaver and seat the fiber into the notch in the lower jaw b Insert the fiber until the stripped portion on the end aligns with the 16 mm mark c Press the scoring bar down on the fiber Take care not to break the fiber ...

Page 27: ...AURORA 2 OVERVIEW SET UP 2 15 Aurora 2 User s Manual Figure 2 16 Cam Splicer Figure 2 17 Cam Splicer Assembly Lock arms Fiber Holders ...

Page 28: ...ACU when the ECU Plus is powered up Failure to observe all CAUTION notices regarding the controls on the ACU may result in damage to the PMT and probe tip The light controls refer to the light on the Aurora 2 head that illuminates the sample area This light is only used in procedures that involve the video monitor and should not be on during NSOM scanning or any time the PMT voltage is turned up N...

Page 29: ... each mirror is performed by loosening the screw underneath the sup porting column Use the yoke supplied with the Aurora 2 to hold the mirror temporarily in place while the position is adjusted Once the position is set tighten the screw under the base of the column The X and Y fine adjust screws are on the mount ROTATING MIRROR The rotating mirror is controlled by a knob on the front of the stage ...

Page 30: ...2 18 Figure 2 20 Reflection Tower Controls Swivel Tilt Focus Rotating mirror selector ...

Page 31: ...rom the cam splicer to the probe The instructions in this section describe how to couple the laser into the laser fiber These instructions apply to the laser and laser coupler sold as options by ThermoMicroscopes The laser coupler consists of two translation stages one for the fiber chuck which can be moved in the X Y and Z focus directions and one for the fine adjustment lens located between the ...

Page 32: ...mp The clamp can be translated in the X Y and Z to position the fiber in the laser beam Step 2 When it is time to use a new fiber remove the coupler chuck from its clamp by unscrewing the lock collar on the end of the coupler and removing the old fiber Step 3 Feed the new fiber through the chuck far enough so you can strip and cleave the end of the fiber Step 4 Carefully strip about 10mm of the po...

Page 33: ...ser The laser is operated on the low setting High power settings may introduce unwanted noise Step 2 The fiber end should be approximately 3 mm from the objective lens This is the focal length for the lens The maximum intensity will be at this 3 mm position Step 3 Aim the free end of the fiber at a flat surface such as a table wall or index card Watch the intensity change as the coupler X Y transl...

Page 34: ... 1 Use the fiber stripper tool to strip away about 25mm of the polymer buffer off the end of the laser fiber Note that once stripped the fiber is very brittle Step 2 Use the optical fiber cleaver from the tool kit to cleave the end of the laser fiber you may also want to refer to the documentation supplied with the fiber cleaver a Open the jaws of the cleaver and seat the fiber into the notch in t...

Page 35: ...ocedure you will need a small piece of paper to use as a beam finder The back of a business card or index card works well for this CAUTION Keep the PMT Voltage on the Aurora Control Unit set to 0 unless the PMT is shielded from all sources of light except the laser during NSOM imaging Exposure to light can damage the PMT The voltage should only be turned up when carefully following the procedures ...

Page 36: ...e image should fill the monitor and no edges should be visible If the edges can be seen use the X and Y fine adjust screws on the camera path flipper mirror mount to center the image Be sure to check both transmission and reflection images after making an adjustment Step 14 Flip the mirror to the down position when finished centering the image Step 15 Using the beam finder find the beam leaving th...

Page 37: ...n contact Atomic Force Microscopy AFM techniques Topo graphic scanning requires learning the techniques for bringing the tip into feedback When the tip is in feedback it can track the topography of the sample thus it is in the near field range of the sample which is necessary for NSOM imaging Chapters 3 and 4 cover this two part technique for taking a scan of the standard sample included with the ...

Page 38: ... software is configured for the Aurora 2 the Non Contact window is automatically open with the Active mode checked upon entering the Data Acquisition mode Step 1 Select Internal Sensor Feedback from the drop down signal source list to the right of the upper oscilloscope Step 2 Select Amplitude from the Mode group box in the Non Contact window Step 3 In the Non Contact window enter the following st...

Page 39: ... than 0 1 Reducing the drive amplitude will cause the internal sensor signal to increase move closer to 0 Increasing the gain will bring the internal sensor signal down more negative i e further from 0 However increasing the gain will propor tionally increase the RMS noise Step 14 Once the Non Contact controls have been fine tuned minimize the Non Contact window To adjust these settings the tip mu...

Page 40: ...ould be low the Integral gain in particular so the tip doesn t jump as it approaches the sample Step 8 Click on the SET button to the right of the internal sensor signal The current internal sensor signal value on the horizontal line at the middle of the window can now be read clearly Step 9 Enter the internal sensor signal value or a slightly lower value to be safe in the SET POINT field Step 10 ...

Page 41: ...e the P I D settings are adjusted to optimize the scan These settings tune the distance control feedback circuit to respond quickly and ac curately to changes in surface topography This gives the best topographic imaging OPTIMIZING THE P I D SETTINGS Step 1 Set the Integral gain between 0 08 and 0 30 This range might change depending on the sample and the specific tip Step 2 Click the LINE scan op...

Page 42: ...pically an indication that the tip is too far from the surface or that the P I D settings are too low Figure 3 2 Sawtooth Line Scan Shape Step 8 When the P I D settings and set point are set properly you will see a quiet stable signal as shown in Figure 3 3 Figure 3 3 Properly Adjusted P I D Settings and Set Point When a scan begins the line scan of the internal sensor signal will no longer be dis...

Page 43: ... the tip in feedback and proceed to Chapter 4 as all the signal parameters are already adjusted correctly Note that it is important to attain some proficien cy in taking topographic scans before taking an NSOM scan CAUTION Do not power down the electronics while the tip is in feedback at the sur face Step 1 Click the Instant Scan button to stop scanning Step 2 Click on the Tip Up button on the Dat...

Page 44: ...3 8 ...

Page 45: ...ivity over time resulting in degraded performance It is a good practice to protect the PMT from high light levels which helps ensure long detector lifetime When concluding an NSOM session wait 10 15 seconds before exposing the PMT to light In general whenever the voltage is supplied to the tube the PMT should be in a dark environment CHECKING FEEDBACK PARAMETERS These parameters should still be se...

Page 46: ...ls list check the FWD checkbox for the NSOM channel Step 10 Bring the tip back into true feedback i e at the sample surface as described in Steps 7 16 under Moving the Tip into Feedback on pg 3 3 The P I D settings should be low the Integral gain in particular so the tip doesn t jump as it approaches the sample Be sure to observe all the Warning and Caution statements Step 11 Increase the P I D se...

Page 47: ...o compensate for any erratic phenomena e g drift indicated by a sawtooth pattern on the Topography trace left slope much steeper than the right slope Or it is possible for the tip to pick up a loose particle from the sample surface Such events are not unusual and there is no need to stop the scan and start over simply make corrections ENDING AN NSOM SESSION CAUTION When concluding an NSOM session ...

Page 48: ... PMT to any light Step 5 Exit the SPMLab software The scanned images can be saved and processed using the SPMLab software which contains a number of analysis and image processing tools Refer to the SPMLab Software Reference Manual for further details ...

Page 49: ...g operation HARDWARE SET UP CAUTION Make sure the power is OFF to all the modules and the computer while setting up Connecting cables to powered up electronics may damage the modules CAUTION Do not activate your light detector when it is exposed to room light as this can cause damage Step 1 Connect a BNC cable from the output of your detector to Input 1 or Input 2 of the I O P Step 2 Make the nece...

Page 50: ...r2 NonInverted Step 3 Open the SPMLab software and enter the Data Acquisition module Step 4 Select SETUP COUNTER The Counter Setup dialog box opens as shown in Figure 5 1 Figure 5 1 Counter Setup Dialog Box TTL OUT This setting determines where the ECU Plus outputs a synchronization pulse DISABLED Counting is not active and both counters will display zero Use this setting for running the non photo...

Page 51: ... module or photon counting PMT do not exceed the maximum count rate Refer to the manufacturer specification You can open a scanning window for each counter to display the counts When the counters are active Counter_1 and Counter_2 will be available as Data Channels when you select SETUP ACQUIRE when the counters are disabled these choices will be grayed out The images from these signals are saved ...

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Page 53: ...stem has to be set up as the beam exiting the fiber NA 0 1 will simply overfill the active detector area The following example describes a collection mode set up using a Hamamatsu photon counting PMT module as shown below After cleaving the fiber at approximately 3mm put the fiber into the guiding groove of the holder and insert it carefully into the 12mm long tube in front of the detector Make su...

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