bi ltd

Birefringence Modulator: Specifications

Configuration:
3-element design with optical element between drive and gauge crystals, providing balanced center of mass mounting.

Birefringence Element:
57.5 x 10 x 10 mm, or 57.2 x 15 x 10 mm, optically polished fused silica.
(180 nm < l < 2000 nm)

Phase Retardation:
Continuously adjustable up to 2p for l = 632.8 nm, up to p for l = 900 nm. Birefringence varies as cos(2x/L) along the optical element, with L the element length, and x measured from the center. The birefringence is within 2% of its center value over a diameter of 11.5 mm.

Modulation Frequency:
Standard: 50 kHz (others can be specified)

Stability:
Modulation amplitude ~0.5% long term stability. Insensitive to room temperature variations, and orientation of modulator head.

Electronics:
50 kHz amplifier with automatic gain control from gauge crystal feedback signal. Voltage monitor for drive and gauge voltage.
Buffered gauge signal available through BNC terminal for lock-in reference. External control input for gauge voltage set value (0 - 2 V). Manual phase adjustment for oscillator.

Computer Interface:
Two options are available:

Interface through any digital-to-analog interface board. A suitable board for IBM compatible systems is available from Beaglehole Instruments (includes basic interface software).
Through Beaglehole Instruments Modular System Microcontroller. The Microcontroller provides automatic calibration and serves as a universal real-time background data acquisition and measurement control device. Includes IgorPro software to control the measurement and display, analyse, and print the measured data. The Microcontroller can be connected to any Windows95, WindowsNT, or MacOS computer via the serial port. Please contact us for more information.