THORLABS LCC25 User manual

LCC25
Liquid Crystal Controller
Operating Manual

Liquid Crystal Controller
18828-D02 Rev F, Sept 23, 2011 Page 2 www.thorlabs.com
Table of Contents
Part 1.Important Safety Notice .................................................................. 4
Part 2.Product Overview ............................................................................ 5
Part 3.Setup and Operation........................................................................ 7
AC Line Voltage.............................................................................................................. 7
Powering ON the LCC25 ................................................................................................ 7
Setting the Voltage and Modulation Frequency.............................................................. 7
Setting the Output ............................................................................................................ 8
Internal Modulation Frequency ....................................................................................... 8
External Modulation Frequency ...................................................................................... 8
Computer Controlled Operation ...................................................................................... 9
3.1.LCC25 Controls and Features.............................................................. 11
Part 4.LCC25 Specifications..................................................................... 12
4.1.Mechanical Drawing.............................................................................. 13
Part 5.Maintenance ................................................................................... 14
5.1.Fuse Replacement.................................................................................. 14
5.2.Ventilation.............................................................................................. 14
5.3.Troubleshooting..................................................................................... 15
Part 6.Warranty Information................................................................... 16
Part 7.Declaration of Conformity ............................................................ 17
Part 8.Regulatory ...................................................................................... 18
Part 9.Thorlabs Worldwide Contacts...................................................... 19

Liquid Crystal Controller
18828-D02 Rev F, Sept 23, 2011 Page 3 www.thorlabs.com
Table of Figures
Figure 1: A 2 kHz Square Wave Output with no Additional Modulation ..................... 5
Figure 2: A 2 kHz Square Wave Output with 150 Hz Modulation................................ 6
Figure 3: Front Display ................................................................................................. 6
Figure 4: LCC25 Front Panel ...................................................................................... 11
Figure 5: LCC25 Rear Panel Features......................................................................... 11
Figure 6: LCC25 Mechanical Drawing ....................................................................... 13

Liquid Crystal Controller
18828-D02 Rev F, Sept 23, 2011 Page 4 www.thorlabs.com
Part 1. Important Safety Notice
Do Not Open Housing!
The LCC25 has no user-serviceable parts. Service should only be
performed by trained service personnel.
All statements regarding safety of operation and technical data in this instruction manual
will only apply when the unit is operated correctly.
SHOCK WARNING
High voltage inside. To avoid electrical shock, before powering
unit, make sure that the protective conductor of the 3-conductor
power cord is correctly connected to the protective earth contact of
the socket outlet. Improper grounding can cause electric shock
resulting in severe injury or even death. Do not operate without
cover installed.
WARNING
This unit must not be operated in explosive environments
Unit is supplied with a 115 V parallel blade line cord for North American use only. For
all other applications use an IEC 320 compatible line cord fitted with a plug appropriate
for your particular AC wall socket.
Make sure that the line voltage rating marked on the rear panel agrees with your local
supply and that the appropriate fuses are installed. Changing of the mains fuse can be
done by the user (see Setting the AC Line Voltage and Installing Fuses). With the
exception of the mains fuses, there are no user serviceable parts in this product.
WARNING
Do Not Operate in Wet/Damp conditions. Do not obstruct the air-
ventilation slots in the housing!
Mobile telephones, cellular phones or other radio transmitters should not to be used
within the range of three meters of this unit since the electromagnetic field intensity may
exceed the maximum allowed disturbance values according to EN50082-1.

Liquid Crystal Controller
18828-D02 Rev F, Sept 23, 2011 Page 5 www.thorlabs.com
Part 2. Product Overview
The LCC25 is a liquid crystal controller compatible with all Thorlabs LC Variable
Retarders. The LCC25 will drive most nematic liquid crystal devices. The liquid crystal
device is connected to the BNC voltage output port. The amplitude of the output voltage,
adjusted by the front panel knob, and external signal, and a computer via a USB interface,
controls the retardance of the LC device.
The LCC25 produces a 2 kHz AC square wave with an amplitude that is adjustable from
0 to 25 VRMS.
The unit features two selectable set points, Voltage 1 and Voltage 2. Both set points are
controlled by the user, and they produce a square wave that is plus/minus the set point.
For example, if the user sets Voltage 1 to 15.000, the output would be a ±15.000V, 2 kHz
square wave (see figure 1).
Figure 1: A 2 kHz Square Wave Output with no Additional Modulation
The user can also select a modulated output with a frequency range of 0.5 to 150 Hz. The
First cycle will be equal to Voltage 1 and the second cycle will be equal to Voltage 2 (see
figure 2)

Liquid Crystal Controller
18828-D02 Rev F, Sept 23, 2011 Page 6 www.thorlabs.com
Figure 2: A 2 kHz Square Wave Output with 150 Hz Modulation
The LCC25 will automatically detect and correct any DC offset in real time to within ±10
mV. This feature increases the life of the liquid crystal device.
The device can be controlled using tactile buttons on the front panel to select the voltage
and frequency and then using the knob to adjust the levels. The system’s display is a
16 x 2 LCD which displays the voltages and frequency (see figure 3). There are two BNC
connectors. The top BNC is the external input and allows the user to input an external
modulation frequency square wave up to 5 volts. The bottom BNC is the system output.
Figure 3: Front Display
The LCC25 may also be controlled by a command line language through the USB port.
This is offered to enable operation through a terminal interface or for those who may
want to write their own program to control the unit.

Liquid Crystal Controller
18828-D02 Rev F, Sept 23, 2011 Page 7 www.thorlabs.com
Part 3. Setup and Operation
To setup the unit, refer to Figures 4 and 5, and the legend table on the preceding page and
perform the following steps:
NOTE: For optimal performance a warm up time of at least 30 minutes is
recommended.
AC Line Voltage
The LCC25 is designed to operate at 100 to 240 VAC operation. There is no line switch
adjustment to be made. However it may be necessary to replace an open fuse. To do this
you must perform the following procedure on page 14, Fuse Replacement.
Powering ON the LCC25
•Connect the appropriate power cord into the AC receptacle and plug the unit in.
•Set power switch to the ON position. Thorlabs will scroll across the display.
Voltage 1, Voltage 2, and the Frequency then will be displayed.
•BNC Output and External input LED indicators will be OFF. This is the default
state when the unit is power on.
Setting the Voltage and Modulation Frequency
There is a set of 6 buttons beneath the LCD display and a knob for adjustment to the left
of the display.
•To change Voltage 1 press the VOLTAGE 1 key, the LCD top left will flash.
Adjust the knob to the desired Voltage.
•To change Voltage 2 press the VOLTAGE 2 key, the LCD bottom left will
flash. Adjust the knob to the desired Voltage.
•To change Frequency Modulation, press the FREQ key, the LCD top right will
flash. Adjust the knob to the desired Frequency.
After pressing the key, the selected voltage or frequency can be saved by pressing the key
while the cursor is flashing or by letting the cursor time out in about 5 seconds. These
settings will be saved during power down and retrieved on power up.

Liquid Crystal Controller
18828-D02 Rev F, Sept 23, 2011 Page 8 www.thorlabs.com
Setting the Output
Output Mode has three selections. Pressing the OUTPUT MODE key will toggle through
each mode. The selected mode will be indicated in the bottom right of the LCD display.
The sequence is as follows: Voltage 1, Voltage 2, and Modulation. To activate the output,
press the OUTPUT ENABLE button. When active, the LED indicator next to the
OUTPUT BNC connector will be lit.
The supported modes are:
•Voltage 1: The output signal will be a 2 kHz
square wave with an RMS voltage level equal
to the value set by Voltage 1
•Voltage 2: The output signal will be a 2 kHz
square wave with an RMS voltage level equal
to the value set by Voltage 2.
•Modulation: The output signal will be a 2 kHz
square wave at an RMS voltage level
switching between the value currently set for
Voltage 1 and the value set for Voltage 2 at the
currently selected frequency.
Internal Modulation Frequency
The LCC25 has internal modulation frequency adjustable from 0.5 to 150 Hz. To use the
internal modulation, the LED next to the EXT INPUT BNC connect should be off. If it is
lit, press the INT/EXT key disabling the LED indicator. To adjust the modulation
frequency, push the FREQ key and adjust the knob to the desired output.
External Modulation Frequency
The LCC25 can be modulated by an external input. The modulation frequency device is
connected to the EXT INPUT BNC. The input signal can be any waveform with a
frequency from 0.5 to 500 Hz, and any duty cycle, but must be 0 and 5 Volts to trigger
the flip. The output from the LCC25 will be modulated based on the input frequency with
Voltage 1 being the high and Voltage 2 being the low.
To select the external modulation, the LED next to the EXT INPUT BNC connector
should be on. If it is not lit, press the INT/EXT key enabling the LED indicator. When the
external input is enabled, the top right of LCD will display EXT and bottom right will
switch to the modulation square -wave symbol (same as modulation is shown above.

Liquid Crystal Controller
18828-D02 Rev F, Sept 23, 2011 Page 9 www.thorlabs.com
Computer Controlled Operation
The LCC25 may also be controlled by a command line language through the USB port.
This is offered to enable operation through a terminal interface or for those who may
want to write their own program to control the unit. The command language is described
below. Prior to running the command line interface, the included drivers should be
installed, the unit should be powered, and a USB cable should be connected between the
LCC25 and the host.
The terminal emulator should be set as follows:
•Baud Rate: 115.2k b/s (bits per second)
•Data Bits: 8
•Parity: None
•Stop Bits: 1
•Flow Control: None
If the connection is correct and after pressing the Enter key, you will see the following:
Command error CMD_NOT_DEFINED followed by the command prompt, “>”
The basic structure of the interface is a keyword followed by either an equals sign (=) or
a question mark (?). The (=) or (?) will determine if the string is a command or a query.
All strings, commands and queries, must be terminated by a carriage return (CR) or
pressing the ENTER key on the computer.
The command structure is as follows:
Keyword = argument (CR)
Where “keyword” defines the function and “argument” is a numerical value followed by
a carriage return (CR).
The query structure is a follows:
Keyword? (CR)
The “keyword” defines the function and the question mark (?) indicates a query. The
string is terminated with a carriage return (CR).
There are a few exceptions to this which are noted below, also noted are unique shortcut
keys. The following table lists the commands and queries available with this device. The
prompt symbol (>) will appear on power up and after a command is accepted by the
LCC25 indicating it is ready to receive another command line.
If the keyword, format, or argument are incorrect or out of range the unit will return an
error string.

Liquid Crystal Controller
18828-D02 Rev F, Sept 23, 2011 Page 10 www.thorlabs.com
Command Syntax* Description
Get ID *idn? Returns the model number and firmware version
Set Voltage 1 volt1=(n) Where (n) equals a voltage between 0 and 25V
Get Voltage 1 volt1? Returns the current voltage set for Voltage 1
Set Voltage 2 volt2=(n) Where (n) equals a voltage between 0 and 25V
Get Voltage 2 volt2? Returns the current voltage set for Voltage 2
Set Modulation Frequency freq=(n) Where (n) equals a frequency between 5 and 150 Hz
Get Modulation Frequency freq? Returns the current modulation frequency
Set Output Mode
mode=0 Sets output mode to Modulation
mode=1 Sets output mode to Voltage 1
mode=2 Sets output mode to Voltage 2
Get Output Mode mode? Returns the current output mode
Set Output Enable enable=0 Output is disabled
enable=1 Output is enabled
Get Output Enable enable? Returns current output enable state
Set External Modulation extern=(n) Where (n) is 0 for internal modulation and 1 for
external
Get External Modulation extern? Returns current modulation mode – internal or
external
Set Preset set=(n) Stores the current settings in the preset (n)
Get Preset get=(n) Restores the settings saved in the preset (n)
Save Parameters save Stores parameters in static memory
Restore Default Parameters default Restores the initial factory settings
Set Test Mode Dwell Time (mS) dwell=(n) Sets the dwell time for LC Test Mode
Get Test Mode Dwell Time (mS) dwell? Returns the current dwell time for LC Test Mode
Set Test Mode Increment (V) increment=(n) Sets the voltage step increment for LC Test Mode
Get Test Mode Increment (V) increment? Returns the current voltage step increment for LC
Test Mode
Set Test Min Voltage (V) min=(n) Sets the starting voltage level for LC Test Mode
Get Test Min Voltage (V) min? Returns the current starting voltage level for LC Test
Mode
Set Test Max Voltage (V) max=(n) Sets the ending voltage level for LC Test Mode
Get Test Max Voltage (V) max? Returns the current ending voltage level for LC Test
Mode
Run Test Mode test Starts the LC Test Mode that will step the output
voltage from the min voltage to the max voltage by
steps equal to increment. At each voltage level it will
delay for the time specified by dwell.
Remote not shown on Display
Normal use of button on display
remote=0 Disables remote from being shown on display.
Normal operation
Remote shown on Display and
current Set voltage
Locks out use of buttons
remote=1 Enables remote shown on display and displays
current Set voltage.
Locks out buttons on from panel.
Command Query ? Returns a list of these commands
*) All commands and queries are in lower case letters.