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ECB Nematic Liquid Crystal
Mode: Electronically Controlled Birefringence | Analog Variable Retarder | Custom Manufactured
Variable Retarder
Analog Control
VIS & NIR
To 90mm Aperture
25 Yrs Experience
ECB (Electronically Controlled Birefringence) is one of the most versatile nematic liquid crystal modes. The retardance at a set wavelength is controlled in analog fashion by voltage — maximum retardance at 0V, switching toward minimum retardance as voltage increases. The birefringence change is a function of the LC tilt angle (polar angle) defined by the substrate normal relative to the molecule's long axis. Setting retardance to half-wave creates a polarization rotator; setting to quarter-wave creates circular polarization. BVO has been manufacturing ECB devices since 1994.
25+ Years
Manufacturing Experience
How ECB Works
In ECB mode, LC molecules are homogeneously aligned (parallel to the glass substrates) at zero voltage. As AC voltage is applied, molecules tilt toward vertical, reducing the effective birefringence. The retardance (Δn × d) decreases continuously as voltage increases — enabling analog control of the phase shift at any wavelength. The zero-voltage state provides maximum retardance; the fully driven state approaches zero retardance.
Because different wavelengths require different retardances for specific polarization states (half-wave, quarter-wave), ECB cells are designed with specific cell gaps (d) and LC birefringence (Δn) for the target wavelength range. BVO characterizes each device for speed, insertion loss, and contrast ratio.
Key Features
- Analog voltage control — continuously tunable retardance from max (0V) to min (high voltage)
- Set to half-wave retardance for a specific wavelength → polarization rotator
- Set to quarter-wave retardance → circular polarization generator
- Custom cell gap and LC fluid selection for target wavelength and retardance range
- Custom apertures from small to 90mm — square or round
- 1mm thick LC cell using 0.5mm thin glass substrates
- Compensation films available to improve dark state and contrast
- Prototype to volume production (1–10,000 units)
- Full performance characterization: speed, insertion loss, contrast ratio
- 25+ years manufacturing custom ECB devices since 1994
Device Specifications (Custom — Contact BVO)
| Parameter | Details |
|---|
| LC Mode | Electronically Controlled Birefringence (ECB) — Homogeneous alignment |
| Voltage Range | 0V (max retardance) to high voltage (min retardance) — analog control |
| Wavelength Range | Visible through NIR — custom to specification |
| Cell Thickness | ~1mm total (0.5mm thin glass substrates) |
| Max Aperture | 90mm |
| Shape | Square or round — custom geometry available |
| Cell Gap | Custom — specified for target wavelength and retardance |
| Birefringence (Δn) | Custom LC fluid selection |
| Compensation Films | Available — BVO designs and supplies |
| Characterization | Speed / response time, insertion loss, contrast ratio |
| Volume | Prototype (1 unit) through high volume (10,000 units) |
| Mounting | Potted into custom mount cups or provided assemblies |
| Zero DC Bias | Required — AC drive only to prevent LC degradation |
Applications
Liquid Crystal Variable Retarders (LCVR)Tune retardance to specific wavelengths for polarimetry, ellipsometry, and polarization state generation. Half-wave for rotation, quarter-wave for circular polarization.
Polarization State GeneratorsGenerate arbitrary polarization states by analog voltage control. Used in Mueller matrix polarimeters and Stokes polarimetry instruments.
Tunable FiltersECB retardance control enables wavelength-selective filtering in Lyot and Šolc filter configurations.
Variable AttenuatorsAnalog intensity control when placed between crossed or parallel polarizers. Smooth, electronically controlled transmission from 0 to maximum.
Laser Beam ControlAnalog polarization rotation for laser power control, beam switching, and polarization management in laser systems.
Scientific InstrumentationCustom ECB retarders for spectroscopy, biomedical imaging, remote sensing, and defense optical systems requiring analog polarization control.
Contact Bolder Vision Optik
