Cyclops - Ultra-Precise Optical Stimulator
Founding developer Jon Newman
Coming soon...
Precise Light Power Control for Optical Stimulation
Optimized for Speed, Precision, Programmability, Ease of Use
Cyclops is a high-power LED driver that enables precise control of light power for optogenetic stimulation. The circuit was developed by Jon Newman while in Steve Potter's lab at Georgia Tech in order to complete his thesis work, which required the delivery of ultra-precise, continuously time-varying light waveforms for optogenetic stimulation. This was, and still is, not possible with commercial hardware for optogenetic stimulation. Since its first use, the circuit has been improved in terms of speed, precision, programmability, and ease of use.
Key Publication
J.P. Newman, M.-F. Fong, D.C. Millard, C.J. Whitmire, G.B. Stanley, S.M. Potter. S.M. Potter. 2015. Optogenetic feedback control of neural activity. eLife (4:e07192).
Circuit Features
Ultra-precise High power Up to 1.5A per LED Wide bandwidth ~2.5 MHz -3 dB bandwidth Maximum 200 ns 1.0A rise-time Current and optical feedback modes Built-in waveform generation Over-current protection Modular Arduino compatible 4 synchronizable optical channels Accepts external analog, gate, or trigger inputs Multiple stimulus generation options External stimulus sequencer External digital trigger TTL logic level External analog waveform generator 0-5V analog signals Internal 12-bit DAC Synchronized across up to 4 drivers Powerful Arduino library Programmable triggering logic Respond to USB input The table below provides a comparisons between Cyclops Rev. 3C and various commercially available LED drivers. Measurements were performed using the same signal generator and LED across drivers. Optical characteristics and optical feedback signal for the Cyclops driver were provided by a Thorlabs PDA36 amplified photodiode set to 0 dB of transimpedance gain.
| Plexon LD-1 | Plexon PlexBright1 | Thorlabs DC4100 | Cyclops (Current FB) | Cyclops (Optical FB) | |
| Speed | |||||
| 10-90% rise time2 (μs) | 49 | 76 | ? | 0.1 | 0.53 |
| 90-10% fall time2 (μs) | 39 | 89 | ? | 0.4 | 0.46 |
| Dead time, worst case2 (μs) | 140 | 160 | ? | 3.0 | 3.0 |
| Small signal -3dB bandwidth4 (kHz) | 10.5 | ? | 1003,5 | 2500 | 2500 |
| Accuracy | |||||
| Overshoot2 (%) | 0 | 0 | ? | 7 (Depends on LED cabling) | 3 (Depends on LED and photodetector cabling) |
| THD6 (%) | 8.29 | ? | ? | 8.2 | 0.41 |
| Power | |||||
| Max current drive (mA) | 1200 | 1100 | 1000 | 1500 | |
| Features | |||||
| Independent LED channels | 1 | 4 | 4 | 1 (modular; can stack up to 4 devices) | |
| Regulated current output | ✓ | ✓ | ✓ | ✓ | N/A |
| Regulated optical output | ✗ | ✗ | ✗ | N/A | ✓ |
| Programmable, hardware-based overcurrent protection | ✗ | ✗ | ✓ | ✓ | |
| Internal arbitrary waveform generation | ✗ | ✓ | ✗ | ✓ | |
| Independent DAC for each LED | N/A | ✗ | N/A | ✓ | |
| Modular design | ✗ | ✗ | ✗ | ✓ | |
| Manual pulse | ✓ | ✗ | ✗ | ✓ | |
| Outputs | None | None | None | Reference voltage, LED current, optical power (if measured) | |
| LCD display | ✓ | ✗ | ✓ | ✗ | |
| Programmability | |||||
| Open-source | ✗ | ✗ | ✗ | ✓ | |
| Driver | N/A | "Radiant" software | NI-VISA based GUI and API | Arduino compabile | |
| Interface | N/A | GUI/USB cable | GUI or API/USB cable | Arduino IDE/USB cable | |
| Waveform generation performance | N/A | 10 kHz aggregate update across channels | N/A | 100 kHz/channel update; evolves with Arduino tools | |
| OS compatibility | N/A | Windows | Windows | Windows, Linux, Mac | |
| Cost | $700 | $5300 | $30597 | ~$1608 | ~$2008,9 |
- Essential drive circuit consists of an Opal-Kelly XEM6001 FPGA Dev board tied to 4 commercially available buck converters from Recon.
- Test signal: 500 Hz, fully off to on, 50% duty-cycle square wave resulting in 1A peak to peak through LED.
- Test signal: 1 kHz 500 mA offset, 100 mA peak-to-peak sine wave.
- Not measured on the bench top. Taken from manufacturer's specifications.
- Bandwidth threshold (e.g. -3 dB) was not specified. Applies to sine wave only.
- Test signal: 1 kHz 500 mA offset, 1A peak-to-peak sine wave.
- Includes the cost of the DC4100-HUB which is required to drive four LEDs.
- Approximate materials cost.
- Increased cost compared to current feedback mode is due to amplified photodiode (design included with Cyclops repository).
