Meadowlark Optics’ Liquid Crystal Variable Attenuator (LCVA) offers real‐time,continuous control of light intensity. Our attenuator consists of an LC Variable
Retarder (with attached compensator) operating between crossed linear
polarizers. With crossed polarizers, light transmission is maximized by applying
the correct voltage to achieve half‐wave retardance from the LC cell. Half‐wave
operation rotates the incoming polarization direction by 90°, so that light ispassed by the second polarizer. Minimum transmission is obtained with theretarder operating at zero (or a whole number of) waves.

Key Features•••High contrast ratio

Transmission decreases as the applied AC voltage amplitude increases (half‐ tozero‐waves retardance). The relationship between transmittance T andretardance (in degrees) for crossed polarizer configuration is given

Computer control capabilities
Continuous control of light intensity

by: T(Θ) = 1/2 [1 ‐ cos(Θ)] Tmax where Tmax is the maximum transmittancewhen retardance is exactly one‐half wave (or 180°).
Maximum transmission is dependent upon properties of the LC Variable
Retarder as well as the polarizers used in your system.
Extinction ratio is defined as the maximum transmission (LC cell at half‐wave)
divided by the minimum transmission (LC cell at zero waves). Values exceeding
1000:1 can be obtained for a single wavelength by optimizing the applied
voltage levels for minimum and maximum transmission. We guarantee a

Liquid Crystal Suite•••Variable Retarders
Liquid Crystal Variable Retarder
UV Variable Retarder
MWIR Variable Retarder
OEM LCVR

minimum extinction ratio of 500:1 at your specified wavelength.
Rotators
Achromatic High Speed Rotator
Binary RotatorPolarization Rotator
Shutters / Attenuators
Achromatic High Speed ShutterHigh Contrast Shutter
Variable Attenuator

Standard Liquid Crystal Variable Attenuator designuses crossed linear polarizers

DS03.19Controllers
Analog Controller
FLC Controller
LC Digital Interface Controller
Temperature Controller
Two Channel High Voltage Controller

POLARIZERS • SPATIAL LIGHT MODULATORS • WAVEPLATES • LIQUID CRYSTAL DEVICES • OTHER CAPABILITIES

Liquid Crystal Variable Attenuatortransmittance and increase damage threshold. With a linearly polarized input beam and a calcite polarizer, transmittance values
exceed 90% at most wavelengths. Very high extinction ratios, in excess of 5000:1, can be achieved with custom doubleattenuators. In this design, two Liquid Crystal Variable Retarders are combined with three polarizers.

Log (Contrast Ratio)

Typical Contrast Ratio of a Liquid Crystal Variable
Attenuator optimized at 550 nm

SPECIFICATIONS
Retarder Material

Nematic liquid crystal with
Birefringent polymer

Polarizer Material

Dichroic polymer

Substrate Material

Optical quality synthetic fusedsilica

We offer standard liquid crystal variable attenuators to coverfour spectral regions:VIS: 450 – 700 nm
IR 1: 650 – 950 nm
IR 2: 900 – 1250 nm
IR 3: 1200 – 1700 nm

Wavelength (nm)Percent Transmittance(normalized to TMAX)

Normalized transmittance of Liquid Crystal
Variable Attenuator with crossed linear polarizers
at a single wavelength

Contrast Ratio

500:1 at single wavelength

Transmitted Wavefront
Distortion (at 632.8 nm)≤ λ/4 (each component)

Surface Quality

40 – 20 scratch‐dig

Beam Deviation≤ 2 arc min

Reflectance (per surface)≤ 0.5% at normal incidence

Diameter Tolerance±0.005 in.

Temperature Range

0˚C to + 50˚C

Recommended Safe OperatingLimit(with dichroic polarizers)

1 W/cm2, CW

Voltage (volts rms)

ORDERING INFORMATION
Unpolarized Transmittance as a function of wavelengthfor LC Variable Attenuator, optimized for 550 nm, withpolarizers and unpolarized input

Percent Transmittance

OTHER CAPABILITIES • LIQUID CRYSTAL DEVICES • WAVEPLATES • MODULATORS SPATIAL LIGHT • POLARIZERSA Liquid Crystal Variable Attenuator can be configured with high efficiency calcite or beamsplitting polarizers to maximize light

Wavelength (nm)Diameter in.
(mm)Clear
Aperture in.
(mm)

Thickness in.
(mm)

Part Number

1.00(25.4 mm)

0.37(9.4 mm)

1.23(31.24 mm)

LVA – 100 – λ

2.00(50.8 mm)

0.70(17.8 mm)

0.75(19.05 mm)

LVA – 200 – λ

3.00(76.2 mm)

1.60(40.64 mm)

1.00(25.4 mm)

LVA – 300 – λPlease specify operating wavelength λ in nanometerswhen placing your order
Custom sizes are available.

www.phototechnica.co.jp〒336-0017 埼玉県さいたま市南区南浦和 1-2-17

TEL:048-871-0067

FAX:048-871-0068

e-mail:voc@phototechnica.co.jp