Product Description:
LDX-3620B is a battery-powered, ultra-low noise current source; Applications for narrow linewidth or stable wavelength laser diodes are optimized. All new instruments provide accurate current output of <100 nA RMS noise and <10ppm stability. The current source can operate in one of two output ranges in constant current or constant power operation mode. In addition, two AC or DC coupled modulation inputs, thick and thin, can control the current source for precise laser diode wavelength or linewidth tuning with a bandwidth of up to 1 MHz. All of the ILX's PROVEN LASER DIODE protection features are designed into each model, which include adjustable current limiting, a FL GOAT output, support relays, slow open circuits, AND transient protection during power-up and laser surgery. Error indicators help resolve setup issues quickly, such as open circuit and power limits. Other features include long battery life between charges, battery charge mode and front panel charge indicator light making the LDX-3620B a reliable test instrument for low-noise, high-precision laser wavelength control applications. The LDX-3620B is a large selection of ILX laser diode can, butterfly, and DIL laser installations compatible with interconnect cables for quick and easy system setup.
Ultra-low noise and high stability
The lead-acid battery and careful design and attention to detail in component selection, instrument and circuit board design enable the LDX-3620B to achieve a sequence of magnitude reduction in noise levels over AC-powered current sources. With correct wiring and laser diode installation, current noise levels <100 nA can be achieved; For spectra, consistent communication and narrow linewidth are required for critical performance in other applications. The same attention to detail also allows the LDX-3620B to achieve sequential current source stability of 10ppm for any operating instrument mode in any hour.
Laser diode protection
Laser diodes are extremely sensitive to electrostatic discharges, excessive current levels, current spikes or transients from power surges or other laboratory equipment. The LDX-3620B protects the laser diode from these potentially destructive events through instrument features such as adjustable current limits and circuit design. Slow start circuits at output power minimize transients and short-circuit relays hold the laser resulting at the same potential until the output has been enabled. Meter current source response tests comply with IEC standards for surge and electrical fast transient (EFT). The current source output is scapegoat relative to FL to the case ground to prevent any potentially damaging common-ground coupling between the instrument or machine and the laser diode.
Selection of laser diode control mode
The LDX-3620B can operate in full scale current constant current low bandwidth, constant current high bandwidth or constant optical power mode. The constant current low bandwidth mode provides a steady DC current supply to the laser diode while providing the lowest current noise. In the constant current high bandwidth mode, the external control voltage is induced into the output current phase, allowing DC or modulated voltage control output up to 1 MHz bandwidth. For laser protection, the modulation port is implemented as a differential input to enable control of the voltage and laser output of the instrument to be used for different reasons. Constant power mode maintains constant light operation of the laser diode by the photocurrent measured from the rear end photodiode or from the external photodiode of the current source in the feedback control loop. Coarse and fine gain adjustments are set on the front panel to scale the operating point of the laser at full scale and allow the feedback loop to operate the current of the photodiode over a wide range.
External current control
The current output of LDX-3620B can be controlled by an external voltage source; A DC signal may be used FOR applications requiring DC bias and/or linewidth broadening, wavelength control or amplitude modulation of AC waveforms. One or two external voltage waveforms can be used to regulate the output current through the modulation input ports on the front panel. Two
The input may be AC or DC coupled to the current source driving circuit. A transconductance difference of 10 for each input is used to modulate and error signals are added to one factor in the driving circuit. In all modes of operation, the voltage input is added to the current controlled laser with the front panel current control.
Long life battery
The LDX-3620B can operate for up to 16 hours on a full charge, making it ideal for nighttime testing. Monitoring the battery level of the instrument at any time during operation is easy with the front panel battery charge indicator light. A switch pushed on the left side of the display indicates charging levels up to 100% at 25% time intervals. Internal batteries provide low noise payments, without the disadvantages of battery powered instruments. Lead-acid batteries with good charge retention and charge recoverability were selected. Dc input with battery charging mode provides the instrument to charge the battery even during instrument operation. The battery low voltage circuit is designed to safely turn off the instrument if the battery charge is below the required instrument operating level.
