High Compliance Voltage Laser Diode Driver; Compliance Voltage Range 24 Volts; Current Range 15 Amps

Product Overview:

LDI Series Laser Diode Driver Modules

The LDI series laser diode diode drivers are precision-engineered to electrically bias high power laser diodes while protecting them from the common causes of damage which can potentially harm or destroy semiconductor lasers. Because high power lasers require relatively high levels of DC current and voltage, and generate high levels of waste heat, they have a unique set of electrical and thermal requirements which need to be addressed to protect them from being damaged. Additionally, the driver has been designed with features to assist the user to safely operate the laser diode under test.

Laser Diode Protection Features

These units offer the highest level of commercially available laser diode protection to ensure that your laser is protected from damage. Current and voltage limits, laser diode temperature limit, and a fast shut-down sequence keep your device protected at all times. The following protection features combine to safeguard your laser diode:

• Polarity Check: A dedicated circuit biases the laser with a very small power level to ensure that it is installed properly to prevent damage caused by incorrect wiring.
• Soft-Start Current Ramp: Gradually increases current to prevent sudden surges that could damage the laser diode. The LDC series units offer the ability for the user to customize the ramp time if desired. The factory default is set to 300 milliseconds.
• Over-current Protection: Prevents excessive current from flowing into the laser diode.
• Over-voltage Protection: Limits the voltage applied to the laser diode.
• Reverse Voltage Protection: Protects against accidental polarity reversal which can permanently damage the diode.
• Thermal Shutdown: Monitors the laser temperature and automatically shuts down if over-heating occurs.
• Current Limit: Allows users to define a maximum current threshold to safeguard the diode.
• Compliance Voltage Limit: Ensures the voltage supplied to the diode remains within safe operating conditions.
• Transient Suppression: Filters out power supply transients and electrical noise that could cause instability.
• Short-Circuit Protection: Detects and prevents damage caused by accidental short circuits in the laser diode current circuit.
• Interlock Safety Mechanism: Requires an external hardware switch or key to enable laser operation, adding an extra layer of safety.

Constant Current Source Laser Diode Driver

The LDI series drivers are based on high stability, low-noise current source topology to ensure optimal performance from your laser diode. They provide exceptionally low drift, allowing for consistent and repeatable results. The constant current source topology is based on a precision sense resistor which is placed in series with the laser diode. The voltage across this sense resistor is fed into a differential amplifier, which compares it to the reference voltage. If the measured current deviates from the setpoint, the feedback loop adjusts the control voltage applied to the pass transistor (MOSFET). The transistor acts as a variable resistor, dynamically adjusting to maintain the desired current. The current source automatically adjusts its output voltage to meet the laser's requirements while keeping the current constant.

Modulation, Internal Function Generator and QCW Modes

In addition to CW (continuous wave) mode of operation, the LDI series laser diode drivers offer flexible modulation capabilities and a built-in QCW function generator. The rear panel of the controller has a BNC input for analog or TTL digital modulation inputs with a 10k Ω input impedance. The controller has an internal function generator which can be used to set the quasi-CW (QCW) pulses. In QCW mode, the user can also set QCW pulses from a remote TTL signal source or by using the internal function generator.

RS232 & USB Interfaces | Analog Signal Controls

These driver modules offer multiple user interface options. For remote control, all models come standard with a RS-232 interface and USB adapter. For all models, the LabView GUI (included) makes set-up and control of the system fast and simple. An open-source terminal software program is also available for download. The user can also control the unit using analog controls signal inputs available on the rear panel.