The Newport 3700 is a high-power thermoelectric temperature controller designed to provide precision thermal management for laser diodes and other optical devices. Delivering 336 W of bipolar output power (±14 A / ±24 V), it drives thermoelectric (TE) coolers in applications where maintaining a stable temperature is critical to laser performance—such as controlling output wavelength, threshold current stability, and preventing thermal aging. A DSP-based fully programmable PID control loop, USB computer interface with LabVIEW drivers, and a comprehensive set of protection features make the 3700 suitable for both laboratory research and production testing environments.

PID Control and DSP Architecture

• DSP-Based PID Control: The controller uses a digital signal processor to execute a fully programmable PID control loop, providing fast settling times and precise temperature regulation across the full operating range. PID parameters can be configured remotely via the USB interface or through the front panel controls.
• Front Panel Lockout: During operation, the front panel controls can be disabled to prevent any changes in the output due to accidental misadjustment, ensuring uninterrupted thermal stability during long experimental runs.
• Complete TE Cooler Characterization: The controller measures and simultaneously displays all pertinent TE cooler parameters—ITE, VTE, and temperature sensor (°C, resistance, current, or voltage)—on the four-line alphanumeric LCD display.

Exceptional Temperature Stability

• Short-Term Stability (<0.0009 °C, 1 h): In a typical lab environment with ambient temperature variations on the order of 2 °C, the 3700 maintained the temperature of a Newport 764H-110 laser mount at 21 °C with a variation of ±0.0004 °C over a 1-hour period with a 10 W laser operating.
• Long-Term Stability (<0.0019 °C, 24 h): Over 24 hours with approximately 3 °C ambient temperature change, the laser mount temperature was held at 21 °C with a variation of ±0.00077 °C.
• Long-Term Drift (<0.002 °C): The 3700 is specified for less than 0.002 °C long-term temperature drift, ensuring consistent laser performance over extended periods.

Multi-Sensor Compatibility and Calibration

• Supported Sensors Without Additional Interface: Thermistors, platinum RTD, AD590/592, and LM335 IC sensors are all supported directly by the controller without requiring external signal conditioning. Sensor calibration constants can be programmed for direct readout in °C.
• Dual Sensor Display Ranges: For thermistor resistance, the controller provides a 10 µA low-current range (0.01 to 250.00 kΩ) to minimize self-heating and a 100 µA range (0.001 to 25.000 kΩ) for higher signal levels.

Computer Interface and Automation

• USB Interface: The 3700 connects to a PC via USB, with Windows-compatible user interface software included. All display parameters, PID settings, and sensor calibration constants are accessible through the software.
• LabVIEW Drivers Included: LabVIEW drivers are provided as standard, allowing integration into automated test systems, data acquisition routines, and production test benches.
• Remote Current Resolution: TE current resolution is 0.1 mA in remote operation mode (1 mA in manual mode).

Comprehensive Safety and Protection

• ITE Limit: Current limit programmable from 0 to 14 A, protecting the TE cooler from overcurrent conditions.
• Hi/Lo Temperature Limits: Programmable upper and lower temperature limit thresholds trigger an automatic shutdown if exceeded, preventing thermal damage to the laser diode.
• Voltage Limits: Output voltage monitoring with configurable limits.
• Sensor Open and TE Open Detection: The controller detects open sensor circuits and open TE connections, immediately disabling the output to prevent damage.
• Automatic Power Management and Failsafe Shutdown: The controller continuously monitors system parameters and automatically shuts down the output if a potentially unsafe condition is detected.
• Noise Prevention: Shielded cables are available to prevent noise pickup by output lines or sensor inputs that could lead to temperature oscillations.

Applications

• Laser diode temperature control for maintaining center wavelength and threshold current stability
• Characterization and performance testing of high-power TE coolers
• Temperature stabilization of optical mounts used in sensitive experiments
• Industrial laser systems and fiber-coupled diode laser assemblies for material processing
• Stabilization of CCDs, detectors, and other semiconductor-based photonic devices