Laser Diode Driver/Controller #85

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opened 2025-08-18 13:44:54 +00:00 by rahix · 1 comment

rahix commented

2025-08-18 13:44:54 +00:00

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For stable operation of a laser diode, its current and temperature need to be controlled very precisely. Commercial setups achieve this with two control loops:

A current controller (e.g. Thorlabs LDC205C) that optionally takes feedback from the laser diode's photodiode to run in constant power mode.
A temperature controller (e.g. Thorlabs TED200C) that is connected to a TEC (thermoelectric cooler = peltier device, Wikipedia) to control diode temperature with a stability of up to 0.002 °C. For temperature measurement, a 10k NTC thermistor is typically used.

For our purposes, we will probably need to build our own controller or replicate an existing design from someone else.

Needs

Current Driver
- Current source with noise below 1µA
- Up to 250mA should be plenty for now (current diodes draw about 80mA and we are not looking for significantly more power)
- Low drift over time
- Photodiode input (transimpedance amplifier) for laser power feedback control
- Second analog input (best also for photodiode) for control loop
Temperature Driver
- Readout resolution of 1mK (relative!), typically used with 10k NTC

Resources

For stable operation of a laser diode, its current and temperature need to be controlled very precisely. Commercial setups achieve this with two control loops: - A current controller (e.g. [Thorlabs LDC205C](https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=10&pn=LDC205C)) that optionally takes feedback from the laser diode's photodiode to run in constant power mode. - A temperature controller (e.g. [Thorlabs TED200C](https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=307&pn=TED200C)) that is connected to a TEC (thermoelectric cooler = peltier device, [Wikipedia](https://en.wikipedia.org/wiki/Thermoelectric_heat_pump)) to control diode temperature with a stability of up to 0.002 °C. For temperature measurement, a 10k NTC thermistor is typically used. For our purposes, we will probably need to build our own controller or replicate an existing design from someone else. #### Needs - Current Driver * Current source with noise below 1µA * Up to 250mA should be plenty for now (current diodes draw about 80mA and we are not looking for significantly more power) * Low drift over time * Photodiode input (transimpedance amplifier) for laser power feedback control * Second analog input (best also for photodiode) for control loop - Temperature Driver * Readout resolution of 1mK (relative!), typically used with 10k NTC #### Resources - [Sam's Laser FAQ — Diode Laser Power Supplies](https://www.lasersam.org/sam/laserdps.htm#dpstoc) - [OpenRAMAN LD & TEC Driver](https://www.open-raman.org/build/performance-edition/custom-ld-tec-drivers/) - [Thorlabs LD3000R OEM Precision Constant Current Driver](https://www.thorlabs.com/precision-constant-current-laser-drivers?tabName=Overview)

rahix added the

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Development

label 2025-08-18 13:44:54 +00:00

forgejo-actions commented

2025-08-18 13:44:58 +00:00

Partial Techtree

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    1["<a href='https://git.fa-fo.de/fafo/techtree/issues/87' target='_blank'>#87</a> | MISSING<br/><i>Equipment</i><br/><b>Diode Laser</b>"]
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Digest: a8109382434f31adaa14c8d34c4df0cbc74aabaca9c403038eed0c0cac921ec6; Last Updated: 2025-10-05 17:01:59

## Partial Techtree ```mermaid flowchart BT classDef eoi fill:#fff, stroke:#000, color:#000; classDef dependant fill:#fff, stroke:#888, color:#888; classDef dep_missing fill:#fcc, stroke:#800, color:#000; classDef dep_assigned fill:#ffa, stroke:#a50, color:#000; classDef dep_completed fill:#afa, stroke:#080, color:#000; 0:::eoi 0["<a href='https://git.fa-fo.de/fafo/techtree/issues/85' target='_blank'>#85</a> | ASSIGNED Development Laser Diode Driver/Controller"] 1:::dependant 1["<a href='https://git.fa-fo.de/fafo/techtree/issues/87' target='_blank'>#87</a> | MISSING Equipment Diode Laser"] 1 --> 0 ``` Digest: a8109382434f31adaa14c8d34c4df0cbc74aabaca9c403038eed0c0cac921ec6; Last Updated: 2025-10-05 17:01:59

rahix added a new dependency 2025-08-18 13:45:17 +00:00

#83 External Cavity Diode Laser (ECDL)

rahix added a new dependency 2025-08-18 14:03:03 +00:00

#87 Diode Laser

rahix removed a dependency 2025-08-18 14:03:31 +00:00

#83 External Cavity Diode Laser (ECDL)