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The Model 3501 Optical Chopper may be programmed remotely by IEEE-488
interface. The Model 3501 supports the IEEE-488.1 (1978) interface standard,
and any computer that supports this interface may be used. A total of fifteen
commands are available that enable any front panel operation to be per-
formed remotely.

Before communicating with the chopper controller, set the IEEE-488 device
address. This parameter may be selected by pressing the Set key until the IEEE
LED is lit. Use the arrow keys to change the device address. The default device
address is 12. Use a standard IEEE-488 cable to connect the instrument to the
host computer.

ACT LED

The ACTive LED flashes whenever data is sent or received on the communica-
tions interface.

Line Terminators

For IEEE-488 operation, the correct line termination is line feed and EOI
('end or identify'). Generally, line terminations are set during the installation
of the IEEE-488 interface card. Consult the manufacturer's installation
instructions for details.

Command Syntax

Use ASCII characters to communicate with the Model 3501. Commands may
be issued either in upper or lower case. 

Some commands can be used to set operating parameters, some commands
can be used to query operating parameters, and some commands can do
both. A command (e.g., WHL?) consists of a mnemonic (WHL) and a optional
suffix (?). The three letter mnemonic (WHL) specifies the parameter or action

VII

Computer

Control

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Summary of Contents for 3501

Page 1: ...l service in house repair center WE BUY USED EQUIPMENT Sell your excess underutilized and idle used equipment We also offer credit for buy backs and trade ins www artisantg com WeBuyEquipment REMOTE INSPECTION Remotely inspect equipment before purchasing with our interactive website at www instraview com LOOKING FOR MORE INFORMATION Visit us on the web at www artisantg com for more information on ...

Page 2: ...Model 3501 User s Manual Optical Chopper Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 3: ...paration for Use IV Quick Start V Operation VI Rack Mount Kit VII Computer Control VIII Command Summary IX Troubleshooting X AC Operating Voltages XI Specifications Is a registered trademark of New Focus Inc Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 4: ...er parts of the Model 3501 Optical Chopper are guaranteed to be free of defects for one year from the date of shipment This is in lieu of all other guarantees expressed or implied and does not cover incidental or consequential loss Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 5: ... motor The motor head has a photo sensor for monitoring the chopping frequency of the outer part of the wheel Fouter The chopper controller then actively stabilizes the motor speed to match the desired chop ping frequency This technique minimizes phase noise at the chopping fre quency and provides for long term stable chopping with a minimum of fre quency drift Figure 1 shows a block diagram of th...

Page 6: ...al Chopper is supplied with four chopper wheels and a wheel cover The Model 3510 Rack Mount Kit an accessory that is sold separately enables the chopper controller to be mounted in a rack see Page 21 Optical Trigger Motor Chopping Head Phase Shifter Ext V 4 Hz 6 4 KHz Micro processor Front Panel H S Norm Out 1 Out 2 f Outer f Synch f Outer Out 1 Out 2 Synch Out Int Synch In Subharmonic Divide by 1...

Page 7: ...e the motor mount onto the optical bench rod and tighten the knob Do not over tighten the knob Mounting the Wheel Remove power from the control unit before attempting to change the chopper wheel Secure the chopper head to a work surface Remove the four 4 40 screws that secure the retaining cap over the wheel while taking care not to bend the wheel Install the replacement wheel retaining cap and 4 ...

Page 8: ...ains that provide a protective ground Wheel Hazard WARNING The moving wheel may inflict injury The operator should assure the safety of personnel who may be exposed to this hazard Safety is important The chopper wheel can cause injury if it is touched while rotating This is especially critical if you find yourself reaching into your opti cal set up with the lights off You may want to use the chopp...

Page 9: ...use inserted into the mains power entry module at the back panel of the con trol unit Connect the instrument to the power mains 5 After insuring the safety of nearby personnel switch on the instrument 6 Recall instrument set up 0 factory default setting Press SET until RECALL is lit Press the up down arrow keys until 0 appears in the display window Press the left or right arrow key to recall set u...

Page 10: ...ion Sync Input Wheel Sync Measure Set Power Mode Synthesizer Output F Outer 60 42 30 7 5 2 V ext EXT EXT INT SYNC IN F outer OUT 1 OUT 2 UNLCK DEG kHz Hz ACT FREQ PHASE H S RECALL STORE IEEE H S NORMAL NEW FOCUS Inc Made in USA 3501 Optical Chopper Fig 2 Front panel of the Model 3501 chopper controller Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 11: ...hopping frequency of the slots on the outer edge of the wheel To change the wheel type push the Wheel key until the LED lights under the desired wheel type Sync The user may synchronize the chopping frequency to the chopper s internal synthesizer INT or the rising edge EXT or falling edge EXT of an externally supplied Sync Input signal When Vext is selected the user may drive the motor directly wi...

Page 12: ...e frequency of the Sync source In INT Sync mode Fsync is the fre quency of the chopper s internal frequency synthesizer In EXT or EXT Sync mode Fsync is the frequency of the externally supplied signal at the Sync Input Set The Set key selects which instrument parameter is modified by the cursor keys Press SET until the LED lights under the desired parameter The up arrow and down arrow keys will th...

Page 13: ...d to the chopping frequency Fouter In NORMAL and modes Fouter Fsync In H S mode Fouter H S Fsync When the phase adjustment is active the DEG LED will be lit The left arrow and right arrow keys select the significant digit to be modified and this digit will blink The up arrow and down arrow keys change the magnitude of the digit H In H S mode the user may lock the chopper to a harmonic of the sync ...

Page 14: ...cond the user may utilize one of ten programmable instrument set ups To recall a previously stored instrument set up use the up arrow and down arrow keys to select instrument set ups 0 9 Press the left arrow or right arrow key to recall the selected instrument set up The display will blink when the recall process is complete Location 0 is reserved for the factory default set tings Default settings...

Page 15: ...justed by setting the FREQ parameter from the front panel or via IEEE 488 With INT sync active the frequency will be limited as given above in the FREQ section With EXT EXT or Vext the Synthesizer Output ranges from 4 00 Hz to 99 9 kHz Fouter The instrument provides the user with a TTL level square wave generated from an optical pick up on the chopper head ACT The ACT LED indicates when the IEEE 4...

Page 16: ...de the instrument provides a TTL level pulse at fre quency H S Fsync In mode the frequency at OUT1 is Fouter Finner and in NORMAL mode the frequency is 5 Fouter OUT2 The function of the OUT2 output depends on the instrument s operating mode In H S mode the instrument provides the user with a TTL level pulse at frequency H 7 S Fsync In mode the frequency at OUT2 is Fouter Finner and in NORMAL mode ...

Page 17: ...may be programmed remotely via IEEE 488 Use a standard cable to connect the instrument to the host computer system Power entry module The AC power is connected at the power entry module on the back panel The line voltage and power cord have been chosen at the factory to match the country of consignment If it is necessary to change the mains voltage con sult the section on AC Operating Voltages Pag...

Page 18: ...le Connect the cable from the connec tor on the side of the chopper head to the MOTOR connector on the back panel of the control unit The instrument has been tested with cable lengths up to 25 feet but the chopper is supplied with a shorter cable Replacement cables and longer cables may be purchased from electronics parts suppliers such as Digi Key Part H2662 14 ND Artisan Technology Group Quality...

Page 19: ... This knob is inserted into the same hole occupied by the dowel on the mounting plate Slide the head onto the optical bench rod and tighten the knob Do not over tighten the knob Chopper Motor The operating life of the chopper motor is limited Long term use of the motor at high speed will result in faster wear and shorter life Contact New Focus for details about replacing the motor if this becomes ...

Page 20: ...ter 4 50 114 3 mm 2 Slot 42 30 Slot 60 Slot 7 5 Slot Fig 5 The four chopper wheels that are supplied with the chopper Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 21: ...e wheel cover will greatly reduce the amount of sensor radiated IR light picked up by your detector To install the wheel cover first install a wheel on the chopper hub Then slide the wheel cover over the top of the wheel while spreading the 2 mounting flanges apart enough to avoid contact with the painted motor surface The motor is 060 080 wider than the mounting base Once the mounting flanges are...

Page 22: ...k mount kit to mount a single chopper controller or two chopper con trollers side by side VI Rack Mount Kit Short Ear Short Ear Short Ear Rack Plate connects two units together 8 50 17 00 Long Ear 3 30 12 35 3 00 3 48 NEW FOCUS Inc Mad e in USA NEW FOCUS Inc Mad e in USA NEW FOCUS Inc Mad e in USA 3510 Rack Mount Kit consists of 2 short ears 1 long ear 1 rack plate 6 6 32 flathead screws Fig 6 Mod...

Page 23: ... LED flashes whenever data is sent or received on the communica tions interface Line Terminators For IEEE 488 operation the correct line termination is line feed and EOI end or identify Generally line terminations are set during the installation of the IEEE 488 interface card Consult the manufacturer s installation instructions for details Command Syntax Use ASCII characters to communicate with th...

Page 24: ...e must be separated by a semicolon Data to Host Data returned by the chopper controller to the host computer consist of a mnemonic a data value and a line terminator The mnemonic specifies the parameter WHL wheel or the quantity measured FR1 Fsync frequen cy Data is returned by the chopper with decimal points included e g 1230 0 Data to the host will be followed with a line termination line feed a...

Page 25: ...rief description of all fifteen com mands Then the pages that follow give detailed information about each command There examples are given showing the command text followed by the response from the chopper For instance the example for IDN appears as follows IDN NEW FOCUS 3501 CHOPPER FR Measures frequency 1 Fsync 2 Fouter 3 OUT1 4 OUT2 HAR Sets the harmonic multiplier H 1 15 IDN Identification que...

Page 26: ...call 0 9 0 factory default set up Use with MEM1 command SET Selects the parameter modified by the arrow keys 0 Oscillator frequency 1 Phase 2 Harmonic multiplier 3 Subharmonic divide ratio 4 Recall set up 5 Store set up 6 GPIB device address STA Returns status register Bit 0 Unlock Bit 1 Data Available The same information is available during a Serial Poll STO Selects instrument set up for storage...

Page 27: ... OUT1 and OUT2 Data is returned in Hz FR1 Fsync FR2 Fouter FR3 OUT1 FR4 OUT2 The chopping frequency is 1 23 kHz and the chopper is in NORMAL mode FR1 FR11230 0 FR2 FR21230 0 FR3 FR36150 0 The frequency at OUT1 is 6 15 kHz Description Command Explanation Example Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 28: ...queries the harmonic multiplier H which is used in H S mode The data may range from 1 to 15 HAR2 Sets H to 2 HAR HAR2 Command Description Explanation Example Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 29: ...turns the following string identifying the chopper NEW FOCUS 3501 CHOPPER IDN NEW FOCUS 3501 CHOPPER Command Description Explanation Example Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 30: ... one of the 9 black front panel buttons The nine options are as follows KEY0 Right arrow KEY1 Down arrow KEY2 Up arrow KEY3 Left arrow KEY4 Set KEY5 Measure KEY6 Mode KEY7 Sync KEY8 Wheel Command Description Explanation Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 31: ...lecting which instrument set up to recall using the RCL command MEM1 recalls the selected set up MEM0 Store instrument set up MEM1 Recall instrument set up STO5 Selects location 5 for storing the current chopper set up MEM0 Activates storage to location 5 RCL1 Selects location 1 for recalling a chopper set up MEM1 Activates recall of the set up stored in location 1 Command Description Explanation ...

Page 32: ...e chopper s operating mode and to set the chopper operating mode as follows MOD0 H S MOD1 MOD2 NORMAL MOD2 Puts the chopper into NORMAL operating mode MOD MOD2 Command Description Explanation Example Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 33: ...s for Unlock and D1 the next bit to the left is for Data Available The MSK query returns the SRQ enable mask MSK1 Generates a SRQ on Unlock MSK MSK00000001 MSK10 Generates a SRQ when data is available MSK MSK00000010 MSK11 Generates a SRQ on Unlock or when data is available MSK MSK00000011 Command Description Explanation Example Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SO...

Page 34: ...imited by the chopper wheel minimum and maximum chopping frequencies In the other modes of operation the data may range from 4 00 to 99 9 kHz Only three digits of resolution are available The data is entered in Hz and no decimal point should be included OSC54300 Sets the internal synthesizer to 543 Hz OSC OSC543 00 Command Description Explanation Example Artisan Technology Group Quality Instrument...

Page 35: ...ge from 180 0 to 179 0 degrees Do not use a decimal point in the data PHS 1234 Sets the phase shift to 123 4 degrees PHS PHS 123 4 PHS222 Sets the phase shift to 22 2 degrees Command Description Explanation Example Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 36: ...t up 0 will restore the Model 3501 to factory default set tings RCL is used with MEM1 to recall the instrument set up RCL0 Select factory default set up for recall MEM1 Perform recall operation RCL4 Select instrument set up 4 for recall RCL RCL4 MEM1 Perform recall operation Command Description Explanation Example Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisa...

Page 37: ...parameter is activated so that it can be changed by the arrow keys SET0 Synthesizer frequency SET1 Phase SET2 H SET3 S SET4 Recall SET5 Store SET6 IEEE 488 device address Command Description Explanation Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 38: ...hown below i e D0 is the rightmost bit A value of 1 indicates the bit has been set and a value of 0 indicates the bit is clear Format of the bits in the status register D0 Unlock sampled D1 Data available D2 Synthesizer locked sampled D3 Multiplier locked sampled D4 Motor locked sampled D5 Latched master unlock D6 Reserved for calibration D7 Reserved for calibration The master unlock bit D5 will b...

Page 39: ...ery will return the selected instru ment set up number The data may range from 1 to 9 STO is used with MEMO to store the instrument set up ST09 Select instrument set up 9 for storage STO STO9 MEMO Perform storage operation Command Description Explanation Example Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 40: ...eries S the subharmonic divide ratio which is used in H S mode The data may range from 1 to 15 SUB7 Sets S to 7 SUB SUB7 Command Description Explanation Example Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 41: ...queries the type of chopping wheel that is being used WHL0 60 slots WHL1 42 30 slots WHL2 7 5 slots WHL3 2 slot WHL1 Selects the 42 30 slot wheel WHL WHL1 Command Description Explanation Example Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 42: ...isconnect the power cord at the power entry module Open the cover of the power entry module using a small blade screwdriver or similar tool Slide the fuse holders out and examine the fuses Replace a blown fuse with the appropriate type and current rating For additional details see page 44 Mains Voltage Make sure that the power entry module is set for the correct mains voltage To set the mains volt...

Page 43: ...tor oscillates wildly Recall the factory default settings This will place the instrument into known conditions If the oscillation stops then the Sync Input signal may have been unstable Verify the stability of Sync Input with an oscilloscope or frequency counter The Sync Input frequency may have been outside of operating limits which are determined by the mode H S and the wheel type Refer to the s...

Page 44: ...le on the rear panel with a small blade screwdriver or similar tool 3 Insert the tool into the voltage selection slot and remove the wheel from the unit 4 Turn the wheel and re insert into the module so the desired voltage is shown Do not attempt to rotate the wheel while it is still in the power entry module the wheel must be removed turned and then re inserted 5 Close the cover 6 Verify that the...

Page 45: ...for the neutral line Replacement fuses should be as follows AC Voltage Fuse Rating Littlefuse 100 V AC 0 4 A 239 400 120 V AC 0 4 A 239 400 220 V AC 0 2 A 239 200 240 V AC 0 2 A 239 200 Figure 7 Power entry module for the Model 3501 Optical Chopper Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 46: ...arm up Drift Less than 10 ppm C Accuracy 1 5 of least significant digit Resolution 4 00 Hz 99 9 kHz 3 significant digits Range limits INT Upper Highest wheel frequency S H Lower Lowest wheel frequency S H Range limits EXT 4 00 Hz 99 9 kHz Reference Input Sync Input TTL level pulse with same frequency limits as internal oscillator XI Specifications Artisan Technology Group Quality Instrumentation G...

Page 47: ...2 TTL level pulse Finner in NORMAL mode Fouter Finner in mode H 7 S Fsync in H S mode Phase Shifter Range 180 0 to 179 0 Resolution 0 1 increasing to 0 25 at 6 4 kHz Harmonic Locking Subharmonic S 1 15 Harmonic H 1 15 S and H may be set in any combination Operation Mode S H OUT1 OUT2 H S 1 15 1 15 H S Fsync H 7 S Fsync 1 12 Fouter Finner Fouter Finner NORMAL 1 5 5 Fouter Finner Artisan Technology ...

Page 48: ...cy Wheel Apertures Wheel Outer Aperture Inner Aperture inches inches 60 09 42 30 14 12 7 5 60 59 2 1 25 General Dimensions 8 5 x 4 x 14 5 inches Weight 14 pounds Power 90 240 V AC 50 60 Hz 35 W Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 49: ...48 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...

Page 50: ...l service in house repair center WE BUY USED EQUIPMENT Sell your excess underutilized and idle used equipment We also offer credit for buy backs and trade ins www artisantg com WeBuyEquipment REMOTE INSPECTION Remotely inspect equipment before purchasing with our interactive website at www instraview com LOOKING FOR MORE INFORMATION Visit us on the web at www artisantg com for more information on ...

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