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Thorlabs’ empty liquid crystal cells are designed for testing liquid crystal compounds and materials. These cells are coated with an Indium Tin Oxide (ITO) conductive layer and a Polyimide (PI) alignment layer (20 µm version has no PI layer). Seven cells are available with various sized spacers to provide cell gaps from 3 µm to 20 µm, and all are designed for simple filling in the lab (See the Filling and ITO tab).
Our empty cells are optimized for high transmission in the visible range, using UV Fused Silica glass, a broadband anti-reflective coating, and thin film, high resistance ITO. If your application requires liquid crystal cells for other wavelength ranges, please contact us for such a custom cell.
Empty cells with cell gaps from 3 to 10 µm are rubbed and assembled for anti-parallel alignment of the liquid crystal. The LCC1324-A has a 20 µm gap and no polyimide alignment layer. This cell is designed for use with materials that do not require an alignment layer, such as Polymer Dispersed Liquid Crystal (PDLC) materials. Thorlabs can also provide cells with different alignment methods such as 90° twist, parallel alignment, or with custom PI material.
Recommended Filling Procedures
Filling Using the Capillary Effect
Filling Using a Vacuum Chamber
After completing the filling using either method, use conductive epoxy such as EG58 to connect wires to the two ITO strips.
The LCC25 liquid crystal variable retarder and polarization rotator controller produces a 2000 Hz square wave output with an amplitude that can be varied from 0 to 25 Vrms. The output amplitude can be set via the front panel controls, the USB interface, and the external input. Both the front panel and USB interface allow the user to select two voltage levels, Voltage 1 and Voltage 2. When the LCC25 is operated in the constant voltage mode, the output of the controller will be a 2000 Hz square wave with an amplitude equal to either of the two set voltage levels (Figure A). If the LCC25 controller is operating in the modulation mode, the output 2000 Hz square wave will be modulated in amplitude between the two voltage settings with a modulation frequency that can be set by the user to be between 0.5 and 150 Hz (Figure B).
The modulated mode can be used to measure the response time of the LC retarder.
External or remote control of the LCC25 is possible using the external input or the USB interface. The external input accepts a 0 to 5 VDC TTL signal that modulates the 0 to 25 Vrms output of the LCC25 between the two set voltages. The USB interface can be used to send line commands to the controller so that the LCC25 can be used in automated lab sequences.
In order to prevent the separation and build up of charges in the liquid crystal layer, the LCC25 will automatically detect and correct any DC offset in real time to within ±10 mV.
Figure A. A plot of the output voltage of the LCC25 Liquid Crystal Controller when it is being operated in the constant voltage mode.
Figure B. A plot of the output voltage of the LCC25 Liquid Crystal Controller when the ouptput voltage is being modulated between the two set voltages.
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Screen shot of the GUI interface in Modulation Mode.
Software for the LCC25 Controller
Custom Software Development
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Back Panel of the LCC25 Liquid Crystal Controller
The LCC25 is a liquid crystal controller compatible with all Thorlabs LC Variable Retarders and Polarization Rotators, as well as being is ideal for driving most other nematic liquid crystal devices. Nematic LC retarders must be driven with an AC voltage in order to prevent the separation and build up of charge, which can cause the device to burn out. In addition to the 2000 Hz AC drive voltage, the LCC25 controller automatically zeros the DC bias across the LC device in order to counteract the buildup of charges. The AC output voltage of the LCC25 controller can be adjusted using the front panel controls, an external 0 - 5 VDC TTL input, and via the USB interface. For more information about the LCC25 controller and for a complete list of its specifications, please see the LC Controller tab.