THORLABS GVS011 User Manual Download Page 25

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Rev 19 Oct 2020

Page 23

5.2 Galvanometer Faults

The driver electronics monitor numerous signals to ensure the scanners operate

safely and the fault protection circuitry will normally prevent any damage.
However, the user should be aware that the galvanometer may become permanently

damaged if the system becomes unstable (manifested by a screeching noise, self

excitation and unpredicable movement of the scanner). In addition the user should

also be aware that the system has no protection against the galvanometer scanners

overheating, and it is left to the user to ensure that they are fitted to an adequate

heatsink (see Section 3.1.1.).
It is worth noting that a fault state may be triggered on applying power to the driver

boards and the power amplifier will be disabled. However in this case the board will

commence normal operation after a delay of a few seconds. The table below shows

the various faults states which can be triggered in the fault control circuitry.

Table 5.1 Galvo System Faults and Associated Fault Protection Circuit Action

Fault

Possible Causes

Action Taken by

Fault Control

Circuit

Maximum scanner position

exceeded

Drive signal too large,

instability of scanner

Power amplifier turned

off

Maximum peak current

Exceeded

Incorrect tuning, instability of the

scanner or overly vigorous drive

waveforms

Power amplifier turned

off

Maximum postion error

exceeded

Incorrect tuning, instability of the

scanner or overly vigorous drive

waveforms

Loop gain reduced

AGC voltage out of normal

range

Broken motor position sensor,

problem with motor cable connection

Power amplifier turned

off

Power supply voltage drops

below minimum value

Poor choice of power supply

Power amplifier turned

off

Maximum RMS coil current

exceeded

Incorrect tuning, instability of the

scanner or overly vigorous drive

waveforms

Power amplifier turned

off

Maximum junction temperature

of power amplifier IC exceeded

Inadequate heatsinking of driver

board

Power amplifier turned

off

Summary of Contents for GVS011

Page 1: ...HA0220T GVS011 and GVS012 GVS111 and GVS112 GVS211 and GVS212 GVS311 and GVS312 GVS411 and GVS412 Large Beam Diameter Scanning Galvo Systems User Guide Original Instructions ...

Page 2: ... Electrical Installation 9 Chaper 4 Operation 18 4 1 General Operation 18 4 2 External Enabling of the driver board 18 4 3 Using a DAQ Card 18 4 4 Recommended Scanning Angles 19 Chaper 5 Troubleshooting 20 5 1 Common Problems 20 5 2 Galvanometer Faults 23 Appendices Appendix A Specifications 24 Appendix B Connecting Legacy Driver Units 27 Appendix C Calculating the Power Dissipation 32 Appendix D ...

Page 3: ...em to be fitted to a PY003 tilt platform The driver cards feature a small footprint fixings for easy mounting to a heatsink and a simple analog command signal interface Typical applications include laser scanning laser display and laser marking A choice of mirror coating is available as follows GVS011 and GVS012 Single and Dual Axis Systems with Protected Silver Mirrors GVS111 and GVS112 Single an...

Page 4: ...he term Galvo refers only to the motor assembly whereas a Galvo Scanner would include the motor together with a mirror mirror mount and driver electronics A description of each component in the system is contained in the following sections 1 2 2 The Galvanometer The galvanometer consists of two main components a motor that moves the mirror and a detector that feeds back mirror position information...

Page 5: ...enhanced stiffness in the mirror assembly also add to system performance by increasing bandwidth and response times Wavelength ranges and damage threshold of the different mirror coatings are details below Fig 1 3 GVS012 Motor Mirror Assembly with GHS003 Heatsink available separately Part No Coating Wavelength Damage Threshold GVS01x Silver 500 nm 2 0 µm 3 J cm2 at 1064 nm 10 ns pulse GVS11x Gold ...

Page 6: ... require vector positioning e g laser marking or raster positioning printing or scanning laser microscopy It can also be used in some step and hold applications Furthermore the proportional derivative circuit gives excellent dynamic performance and includes an additional current term to ensure stability at high accelerations The diagram below shows the architecture of the driver in more detail Fig...

Page 7: ...Risk of Electrical Shock Given when there is a risk of injury from electrical shock Warning Given when there is a risk of injury to users Caution Given when there is a risk of damage to the product Note Clarification of an instruction or additional information Warning If this equipment is used in a manner not specified by the manufacturer the protection provided by the equipment may be impaired In...

Page 8: ...erent cables will affect the performance of the system Caution The driver circuit board is shipped calibrated and ready for use The only adjustments necessary are setting the Volts Degree Scaling factor see Section 3 2 5 and if required setting the device for external enabling see Section 4 2 Do not attempt to make any other adjustments or remove fit any other jumpers than those explicitly describ...

Page 9: ...n particular the 2 axis GVS012 is set for optimum orientation between the two galvo mirrors Under normal circumstances the position of the units in the clamp should not be altered If the need arises for the units to be repositioned a hex key is provided to adjust the set screw It should be noted that this set screw is M4 irrespective of whether the galvo units are imperial or metric M versions The...

Page 10: ...e mounting bracket will provide adequate heat sinking however for more vigorous applications it may be necessary to fit some heatsinking in addition to the galvo motor mount Thorlabs supply a heatsink GHS003 suitable for both single and dual axis applications If using a third party heatsink please see Appendix C for details on how to calculate the power dissipation in the motor 1 Note the orientat...

Page 11: ...troller board s as this power supply has been specifically designed for this purpose The GPS011 can power up to two driver cards under any drive conditions and is supplied with all the cables required to connect to the driver cards However customers also have the option of using a third party power supply or incorporate the boards into their existing system In this case care must be taken to ensur...

Page 12: ...n order to ensure that the power supply reservoir capacitors on the board are not damaged by the large surge currents that can occur on power up Most power supplies naturally soft start when they are switched on at the mains side and provide inrush current limiting If however the power supply is turned on at the output DC side it can output its peak current instantaneously In this case it is impor...

Page 13: ...ions Caution Selecting the incorrect voltage range or fuse will damage the unit Ensure that both switches are set to the correct position for your region and that the fuse fitted is of the correct rating as indicated by the screen print on the rear panel Caution During the electrical installation cables should be routed such that power and signal cables are separated so that electrical noise pick ...

Page 14: ...U see vc 2 The circular 3 pin connector on the power output cable and the OUTPUT socket on the PSU are fitted with alignment key ways to ensure connection in the correct Caution This section is applicable only to driver card units with a PCB at rev 11 or later For details on connecting earlier units please see Appendix B PCB revisions can be identified as follows Up to and including issue 10 Issue...

Page 15: ...gnment key ways then make connections as shown in Fig 3 6 3 Screw the outer casing of the plug clockwise until the connector is fully fastened Fig 3 6 Connecting the Power Cable to the PSU Fig 3 7 Connector Identification OUTPUT 15V DC 3 0A 0 1A 1 4 6 3 msec OUTPUT 15V DC 3 0A 0 1A 1 4 6 3 msec J9 J6 J10 J7 JP4 JP7 ...

Page 16: ...ver board as shown below Fig 3 9 J9 Motor Connector Pin Identification Caution During items 5 and 6 use only the cables supplied Do not extend the cables The driver boards and motors are calibrated with these cables Using different cables will affect the performance of the system Longer cables are available as a custom part but the units will require re calibration if these are not specified at ti...

Page 17: ...grees mechanical movement The driver will attempt to set the mirror position to the command input value Pin 3 DRV_OK is an open collector output that is low when the board is operating normally and floating if a fault occurs To use Pin 3 as a fault indicator connect a pull up resistor to give a high signal when the fault occurs DRV_OK limits are 30 mA 30 V Do not connect a relay to this output 1 3...

Page 18: ...G Manufacturer Molex Mfr P N 56134 8100 Example Vendor Farnell Vendor P N 1120545 Crimps 22 28AWG Manufacturer Molex Mfr P N 56134 9100 Example Vendor Farnell Vendor P N 1120546 Note All diagnostic signals from J6 have 1 KW output impedance except Pin 7 Motor Coil Voltage 2 which has 5 KW 1 2 3 4 8 7 6 5 Function Generator J7 1 2 7 8 Function Generator J7 1 2 7 8 Standard O P Differential O P Eart...

Page 19: ...ts the drive voltage to the side of the motor coil It is scaled down by a factor of 2 The drive voltage determines the current which then determines the acceleration It is not required if the user only wants to monitor position 3 2 5 Setting the Volts Degree Scaling Factor The servo driver cards have a jumper which is used to set the Volts per Degree scaling factor The cards are shipped with the s...

Page 20: ...ve electronics will be enabled If a logic low signal is applied then the driver will be disabled 4 3 Using a DAQ Card Typically users will deploy a DAQ card with DAC analogue outputs in order to drive the servo drivers supplied with the galvos The minimum recommended specifications for the DAC outputs are Dual bipolar 10V to 10V DAC analogue output channels differential DAC clocking frequency high...

Page 21: ...movement from the center as shown below Lastly on dual axis systems there is an offset alignment between the X and Y axis mirrors that also limits the scan angle The table below gives recommended scanning angles for various beam diameters GVS011 GVS111 GVS211 GVS311 and GVS411 Input Beam Diameter Mechanical Scan Angle Optical Scan Angle 7 mm and less 20 40 8 mm 20 16 40 32 10 mm 20 8 40 16 GVS012 ...

Page 22: ...amage to the scanners However under normal circumstances the instability should be detected by the fault control circuitry In this case the behaviour most likely to be observed by the user is the following The mirror will suddenly jump from one position to another probably with a short burst of whistling and stop and remain still After a delay of a few seconds the mirror will jump to another posit...

Page 23: ...lvo system is drawing more current than expected if the scanners or the driver cards are overheating if the scanners are making a hissing noise or if the position accuracy is less than expected this may be due to oscillations in the galvo motor current This can be identified by viewing the coil current signal J6 pin 4 on an oscilloscope The problem will manifest itself as a high frequency 1kHz sin...

Page 24: ... will grow with time until a fault is triggered There is usually a certain frequency and amplitude above which this starts to occur This behaviour is caused by choosing a power supply which cannot deliver enough current for the intended application The oscillation builds up because the power supply voltage is dropping on the rising edge of the position signal and effecting the board s behaviour Wi...

Page 25: ...s the various faults states which can be triggered in the fault control circuitry Table 5 1 Galvo System Faults and Associated Fault Protection Circuit Action Fault Possible Causes Action Taken by Fault Control Circuit Maximum scanner position exceeded Drive signal too large instability of scanner Power amplifier turned off Maximum peak current Exceeded Incorrect tuning instability of the scanner ...

Page 26: ...Beam Vertical Offset a 14 7 mm 0 58 Finish GVS01x Protected Silver Coated GVS11x Protected Gold Coated GVS21x Broadband E02 GVS31x Dual Band Hi Power K13 GVS41x UV Enhanced Aluminum Damage Threshold GVS01x 3 J cm2at 1064 nm 10 ns pulse GVS11x 2 J cm2 at 1064 nm 10 ns pulse GVS21x 0 25 J cm2 at 532 nm 10 ns pulse GVS31x 5 J cm2 at 1064 nm 10 ns pulse GVS41x 0 3 J cm2 at 355 nm 10 ns pulse Wavelengt...

Page 27: ...Travel 99 9 Scale Drift b 200 PPM C Max Zero Drift b 20 µRad C Max Repeatability 15 µRad Resolution With GPS011 Linear PSU With standard switch mode PSU 0 00086 15 µRad 0 004 70 µRad Average Current 1 A Peak Current 10 A Load Mirror Aperture 10 mm Maximum Scan Angle Mechanical Angle 20 with 0 5V scaling factor Motor Weight inc cables excl bracket 94 g Recommended Operating Temperature Range 15 to ...

Page 28: ... Electronics Full Travel Bandwidth c 25Hz Square wave 35 Hz Sinewave Bandwidth 50 Full Travel d 65Hz Square wave 130 Hz Sinewave Small Angle 0 2 Bandwidth d 1kHz Small Angle Step Response e 400 µs Power Supply 15V to 18V dc 1 25 A rms 10A peak MAX Analog Signal Input Resistance 20k 1 Differential Input Position Signal Output Resistance 1K 1 Analog Position Signal Input Range 10V Mechanical Positio...

Page 29: ...B Connecting Legacy Driver Units Caution This section is applicable only to driver card units with a PCB earlier than rev 11 For details on connecting later units please see Section 3 3 3 PCB revisions can be identified as follows Up to and including issue 10 Issue 11 onwards ...

Page 30: ... a suitable PSU GPS011 for powering a single or dual axis system see Section 3 2 1 A bare cable crimp connectors Molex Pt No 2478 and housings for use with general lab PSUs is supplied with each driver board Fig B 2 J10 Power Connector Pin Identification Caution During the electrical installation cables should be routed such that power and signal cables are separated so that electrical noise pick ...

Page 31: ...al analog command input If the scaling is 0 5 Volt per degree mechanical movement see Section 3 2 5 10 V to 10 V gives 20 to 20 degrees mechanical movement The driver will attempt to set the mirror position to the command input value Pin 3 DRV_OK is an open collector output that is low when the board is operating normally and floating if a fault occurs To use Pin 3 as a fault indicator connect a p...

Page 32: ...e command signal following amplification by the input stage The scaling is 0 5 Volt per degree of mechanical movement Positioning Error x 5 This signal is proportional to the difference between the demanded and the actual positions Position Command x 5 i e Pin 1 pin 2 x 5 Motor Drive Current The drive current of the motor 2V per A i e if drive signal is 2V the drive current is 1 A Motor Coil Volta...

Page 33: ...ree scaling factor The cards are shipped with the scaling set to 0 5 V where the max mechanical scan angle is nominally 20 for the full 10 V input To set the scaling factor to 0 8 V or 1 0 V proceed as follows 1 Identify JP7 as shown in Fig 3 13 2 Set the jumper position for the corresponding scaling factor as shown below Fig B 6 Setting the Volts Degree Scaling Factor 1V 0 8V 0 5V JP7 ...

Page 34: ...is positive supply voltage and V is the negative supply voltage 3 1 1 Calculating the Required Thermal Conductivity The ability of a heatsink to transfer heat to its surroundings is parameterised either by its thermal conductivity k or its thermal resistance Ø The lower the thermal resistance the more effectively the heatsink can transfer heat The required thermal resistance can be calculated from...

Page 35: ... the fact that the distance between mirror 1 and the image field depends on the size of the mechanical scan angles of mirror 1 and mirror 2 A larger scan angle leads to a longer distance 2 The distance in the image field is not proportional to the scan angle itself but to the tangent of the scan angle Therefore the marking speed of the laser focus in the image field is not proportional to the angu...

Page 36: ...ual Axis Scanning Galvo Systems for Large Beam Diameters As a result you will find the scanning field turn out to be a pillow shaped image see Fig D 2 below Fig D 2 Pillow shaped Field Distortion Caused by the Arrangement of Mirrors ...

Page 37: ...st harmful interference when the equipment is operated in a commercial environment This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause harmful interference to radio communications Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be ...

Page 38: ...Page 36 20381 D02 Single and Dual Axis Scanning Galvo Systems for Large Beam Diameters E 2 CE Certificates ...

Page 39: ...right were sold to and are currently owned by a company or institute within the EC and are not dissembled or contaminated Contact Thorlabs for more information Waste treatment is your own responsibility End of life units must be returned to Thorlabs or handed to a company specializing in waste recovery Do not dispose of the unit in a litter bin or at a public waste disposal site USA Canada and Sou...

Page 40: ...www thorlabs com ...

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