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Doc 12536-D03 Rev D 9/19/2005 

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Section 8: Operating Instructions 

8.1 Internal Frequency Synthesizer  

The MC1000A is most frequently used in this mode where the chopper wheel frequency is locked to an internal crystal 
stabilized frequency reference. The PLL motor speed control circuit maintains a precise lock to the frequency and phase 
of the internal reference frequency creating an ultra-stable chopping signal.  

8.1.1 Setup for Internal Reference Frequency 

1.  Follow the setup procedures in the ‘Getting Started Quickly’ section. 

2.  Turn the MC1000A power on. 

3.  If the ‘EXT EN’ LED is lit, press button under the LED to return the unit to the internal frequency mode. 

4.  Set the chopper operating speed as desired using the ‘

’ or ‘

’ keys. While holding down these keys, the set 

speed will be displayed but the motor speed will not change until the key is released. 

5.  After releasing the keys, the chopper should adjust its speed and lock onto the reference within a few seconds as 

indicated by the chopper speed shown on the digital display. 

8.1.2 Selecting the REFERENCE OUT signal 

In the internal frequency mode, the reference output signal can be set to the actual chopper wheel frequency or the 
internal frequency synthesizer. In most cases, such as when selecting a reference for a lock-in amplifier, the chopper 
wheel frequency will be used since it provides a direct measurement of the chopper phase and frequency. The chopper 
wheel reference is derived from a photo-interrupter on the optical head that senses the motion of the chopper blade. 

The internal frequency synthesizer has slightly less phase jitter than the chopper wheel reference since it is not affected 
by external disturbances. Therefore, there may be cases where using the internal synthesizer as the reference output 
yields better performance (i.e. when synchronizing multiple choppers). 

1.  Press the ‘MODE’ key until the ‘REF SELECT’ LED is lit. 

2.  Press the ‘

’ or ‘

’ key repeatedly until the desired reference output signal is shown. Once the key is released, 

the selected reference signal will be routed to the front panel BNC labeled REF OUT. 

Note: the display prompt for the direct chopper wheel frequency is ‘

OUT

’. The internal synthesizer display prompt is  

SYN

’. 

8.1.3 Why doesn’t the motor speed exactly match the set speed? 

The MC1000A internal frequency synthesizer uses a 1.000MHz crystal oscillator, which is divided down by a 32-bit digital 
divider to generate the reference signal to lock the chopper wheel to. The MC1000 microprocessor uses an advanced 
algorithm to match the set speed as closely as possible. However, there are some frequencies that cannot be achieved 
exactly. This is due to the limitations of dividing the 1.000MHz clock by a 32-bit integer divisor, and does not affect the 
stability of the chopper frequency. 

8.2 External Reference Mode 

A major benefit of using a PLL circuit to control the chopper wheel speed is that the chopper can be locked precisely to an 
external reference signal. This allows the MC1000A to be used in advanced setups, for example, multiple MC1000A 
choppers can be synchronized to a single reference signal, or master-slave combinations where one chopper is the 
master reference and a second chopper is slaved off the reference output of the first. The latter example provides a 
convenient way to measure long decay time fluorescence and other similar types of experiments. 

The MC1000A will accept a TTL or CMOS logic level input as an external reference. The advanced PLL design used in 
the MC1000A even accepts reference signals that do not have a 50% duty cycle. A special feature of the external 
reference mode, locking to harmonics and sub-harmonics of the reference signal, is described in the following section. 

Note: Having an active external reference attached to the ‘EXT REF IN’ during MC1000A power up may cause the unit to 
lock up. If this occurs, remove the external reference connection, and recycle the power. When the unit finishes its startup 
sequence, attach the external reference signal. 

Summary of Contents for MC1000A

Page 1: ...al Related Products Model Description MC1F2 2 slot Replacement Blade 1 99Hz MC1F10 10 slot Replacement Blade 25 1kHz MC1F15 15 slot Replacement Blade 38 1 5kHz MC1F30 30 slot Replacement Blade 75 3kHz MC1F60 60 slot Replacement Blade 150 6kHz MC2F57 Dual Slot 5 Inner 7 Outer Replacement Blade _________________________________________________________________________________________________ Doc 1253...

Page 2: ...N 5 FUSE REPLACEMENT LINE VOLTAGE SELECTION 9 5 1 MATERIALS NEEDED 9 5 2 FUSE REPLACEMENT AND LINE VOLTAGE SELECTION 9 SECTION 6 GETTING STARTED QUICKLY 10 6 1 SETUP 10 6 2 INTERNAL REFERENCE OPERATING MODE 10 6 3 EXTERNAL REFERENCE MODE 10 SECTION 7 DESCRIPTION 11 7 1 CONTROLLER FRONT PANEL FEATURES 11 7 2 CONTROLLER REAR PANEL FEATURES 12 7 3 OPTICAL HEAD 13 SECTION 8 OPERATING INSTRUCTIONS 14 8...

Page 3: ...PING 15 8 4 1 Setting the Chopping Speed in the 2 Frequency Mode 16 8 5 SETTING THE CHOPPER BLADE 16 8 6 2 SLOT BLADE 16 SECTION 9 SERIAL PORT 17 9 1 SERIAL PORT PARAMETERS 17 9 2 SERIAL PORT PIN OUTS 17 9 3 SERIAL INTERFACE COMMAND SCREEN 17 9 4 SERIAL COMMAND SUMMARY 18 SECTION 10 MAINTENANCE AND TROUBLESHOOTING 19 10 1 CLEANING 19 10 2 DIAGNOSTIC MESSAGES 19 SECTION 11 CONTACTS 19 USA CANADA AN...

Page 4: ...ver cards components mechanics and optics left over parts of units disassembled by the user PCB s housings etc If you wish to return a Thorlabs unit for waste recovery please contact Thorlabs or your nearest dealer for further information Waste treatment on your own responsibility If you do not return an end of life unit to Thorlabs you must hand it to a company specialized in waste recovery Do no...

Page 5: ...THE UNIT MUST BE POWERED OFF UNPLUGGED FROM THE AC INPUT POWER SOURCE AND DISCONNECTED FROM ALL EXTERNAL DEVICES BEFORE REMOVING THE COVER AND REPLACING THE FUSE FAILURE TO DO SO MAY CAUSE SERIOUS INJURY TO THE USER SINCE HIGH VOLTAGES EXIST WITHIN THE UNIT Thorlabs ships all units configured to operate in the United States i e line voltage 115VAC 60Hz and 250mA fuse installed It may be necessary ...

Page 6: ...le between 115 230 VAC Input Voltage 100 115VAC 10 230VAC 10 Line Frequency 50 60Hz Input Power 20VA max Fuse Ratings 250mA 115VAC 125mA 230VAC Fuse Type IEC60127 2 III 250V Slow Blow Type T Fuse Size 5 x 20mm 2 3 Input Output Specifications Ext Input Compatibility TTL CMOS Ext Input Voltage Range2 0 5V Input High 2V Input Low 0 8V Ext Input Impedance 200Ω Ref Out Compatibility TTL CMOS Ref Out Vo...

Page 7: ...e Specifications Chopping Blade Slots4 MC1F2 2 MC1F10 10 Default Blade MC1F15 15 MC1F30 30 MC1F60 60 MC2F57 7 Outer 5 Inner Slot Angle MC1F2 180 MC1F10 36 Default Blade MC1F15 24 MC1F30 12 MC1F60 6 MC2F57 51 4 Outer 72 Inner Notes 1 The MC1000A is supplied with a US style power cord Units purchased in other countries must supply their own certified rated power cord 2 The reference output and exter...

Page 8: ...m at the inner frequency The MC1000A provides the sum and difference frequencies of the 2 frequency blade for accurate lock in detection of the frequency mixed response A high quality Swiss made rare earth magnet DC motor and a photo etched chopper optical wheel drive the precision The compact optical head has a wide base for extra stability The base is slotted for two 20 mounting screws on 2 cent...

Page 9: ...unit at 100 115VAC Phillips Head Screwdriver 2 Preferred We do not recommend using electrically powered screwdrivers 5 2 Fuse Replacement and Line Voltage Selection 1 Important Disconnect the optical head and any external devices from the MC1000A BNC s 2 Important Disconnect the power cord Do not open the unit if the power cord is connected See warning above 3 Remove the two screws securing the en...

Page 10: ...ng speed is set by the internal crystal stabilized frequency synthesizer 1 Turn the MC1000A power on The LED display will go through a startup sequence first all of the display segments and LED s are lit then the firmware rev level is displayed followed by the current blade setting 2 The display should show b 10 for the 10 slot blade If not press the key until the b 10 message is displayed and the...

Page 11: ...NTER to save the setup to that number Note the setup number will wrap around back to 1 after it reaches 5 when pressing the FREQ UP CYCLE key 8 RECALL SETUP In this mode the user can recall one of the five user setups Select the setup number with the FREQ UP CYCLE key and press the FREQ DOWN ENTER to restore the saved configuration 9 SET D This mode allows the user to select a sub harmonic of the ...

Page 12: ... used for cycling through input options for other operating modes 7 2 Controller Rear Panel Features OPTICAL HEAD WARNING GROUNDING CONDUCTOR MUST BE CONNECTED TO GROUND REFER SERVICING TO QUALIFIED PERSONNEL TO AVOID ELECTRICAL SHOCK THE POWER CORD PROTECTIVE RS232 250mA FUSE 125mA FUSE 100 115VAC 50 60Hz 50 60Hz 230VAC 1 2 3 4 MAX POWER 20VA WWW THORLABS COM USE 250V TYPE T 5X20MM SLO BLOW FUSES...

Page 13: ... 15 30 or 60 slots and a 7 5 2 frequency 2 1 16 Hex Mounting Screws and lock washers qty 3 3 Photo interrupter Speed Sensor 4 Blade Hub 5 Modular Interface Connector 6 Mounting Base _________________________________________________________________________________________________ Doc 12536 D03 Rev D 9 19 2005 Page 13 of 22 ...

Page 14: ...ppers 1 Press the MODE key until the REF SELECT LED is lit 2 Press the or key repeatedly until the desired reference output signal is shown Once the key is released the selected reference signal will be routed to the front panel BNC labeled REF OUT Note the display prompt for the direct chopper wheel frequency is OUT The internal synthesizer display prompt is SYN 8 1 3 Why doesn t the motor speed ...

Page 15: ...rmonic modes are not available when using 2 frequency blades 8 3 1 Setting the Reference Harmonic 1 Press the MODE key until the SET N LED is lit The current value for N is displayed Use the CYCLE key to select the desired harmonic The display will wrap around to 1 after it reaches 15 2 Once the key is released the MC1000 will apply the reference signal to the multiplier circuit and the reference ...

Page 16: ...n only be done during the startup sequence When the MC1000A is powered on it goes through the following startup sequence 1 A lamp test with all of the display segments and LED s lit for about a second 2 The firmware revision level is displayed please take note of this number when calling tech support 3 The current blade setting is displayed At this point the MC1000A can be set to the appropriate b...

Page 17: ...le from the serial port to control the chopper For experienced programmers the chopper serial interface may be incorporated into a user program developed on a serial port system 9 1 Serial Port Parameters 9 2 Serial Port Pin Outs Baud Rate 19 200 Data Bits 8 Stop Bits 1 Parity none Handshake none DB9F pin Signal 1 7 8 9 no connect 2 TxD from MC1000 3 RxD to MC1000 4 connected to pin 6 5 Signal Gro...

Page 18: ...to 1000 10 slot 30 to 1500 15 slot 60 to 3000 30 slot 120 to 6000 60 slot 14 to 700 2 f blade and 50 to 4950 2 slot Description This sets the internal reference frequency Note the range is dependent on the blade Note The 2 slot blade must be set using the outer blade frequency There are 100 outer slots and 2 inner slots with a 50 1 ratio Therefore to set the blade rotation to 10Hz the set value mu...

Page 19: ...oC This indicates that the chopper speed could not lock to the set frequency or the external reference If this occurs check the unit has been set to the correct blade as indicated on power up If this problems persists contact Thorlabs for assistance rEF This message is displayed when the unit is set to external reference but it does not detect an external reference input Check that your external r...

Page 20: ...Appendix A Certifications and Compliances _________________________________________________________________________________________________ Doc 12536 D03 Rev D 9 19 2005 Page 20 of 22 ...

Page 21: ...e criterion B IEC 61000 4 3 Radiated RF Electromagnetic Field Immunity Performance criterion B IEC 61000 4 4 Electrical Fast Transient Burst immunity Performance criterion B IEC 61000 4 5 Power line Surge Immunity Performance criterion C IEC 61000 4 6 Conducted RF Immunity Performance criterion C IEC 61000 4 11 Voltage Dips and Interruptions Immunity Performance criterion C EN 61000 3 2 AC power l...

Page 22: ...e following specification as listed in the Official Journal of the European Communities Low Voltage Directive 73 23 EEC amended by 93 68 EEC EN 61010 1 A2 1995 Safety requirements for electrical equipment for measurement control and laboratory use Additional Compliance IEC61010 1 A2 1995 Safety requirements for electrical equipment for measurement control and laboratory use Equipment Type Test and...

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