2 layers70 × 35 mm
Speckle amp pcb rev2
bitmorse/specklesensor
A photodiode array for laser speckle sensing and vibrometry.
55 parts1MIT
2 layers
Dot projector
bitmorse/specklesensor1A photodiode array for laser speckle sensing and vibrometry.
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 7
- Nets
- 7
- Pads
- 29
- Tracks, vias
- 39, 22
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 9 Jan 2025
- Updated
- 10 Jan 2025
Overview
Dot projector is an open-source printed circuit board by bitmorse, from the bitmorse/specklesensor repository on GitHub, published under the MIT licence. It is a 2-layer board with 7 parts on 7 nets, routed with 39 tracks and 22 vias.
Its parts include 3 capacitors, 1 resistor, 1 IC and 1 connector.
README
README.mdspecklesensor
A photodiode array for laser speckle sensing and vibrometry.
Read the full paper here.
Spectral analysis of a 133 Hz surface vibration under different laser configurations. Top: Power spectral density showing the target frequency component. Bottom: SNR improvement with increasing number of active lasers:
RPI Camera Bench Setup
Side by side comparison of the speckle pattern captured by a Raspberry Pi camera with one red laser
and three red lasers.
Laser setups
Hardware
The PCBs used for the experiments are in the hardware folder. The PCBs are designed using KiCad, an open source schematics and layout editor. The PCBs were manufactured by JLCPCB and hand assembled using hot air reflow.
speckle_pcb_rev1: The 3x3 photodiode array.speckle_amp_pcb_rev1: The amplifier PCB for 3x3 array.
Careful attention must be paid to cleaning the PCBs after soldering, as any residue flux can lead to leakage currents and noise in the measurements.
Scripts
emulations: The script to process camera frames to CSV files for emulating the photodiode array. A notebook provides the signal processing.waveshare: Scripts for testing the first ADC.daqhat: Scripts for testing the second ADC and data from the multi-laser experiment.
Parts
7| Qty | Value | Footprint | References |
|---|---|---|---|
| 2 | 100n | Capacitor_SMD:C_0603_1608Metric | C2, C3 |
| 1 | 0 | Resistor_SMD:R_0603_1608Metric | R1 |
| 1 | 1u | Capacitor_SMD:C_0603_1608Metric | C1 |
| 1 | Conn_01x06_Pin | Connector_PinHeader_1.27mm:PinHeader_1x06_P1.27mm_Vertical | J1 |
| 1 | D_Laser_1C2A | lib_fp:ams_belago1.1 | LD1 |
| 1 | IC-HKBSO8-TP | lib_fp:SOIC127P600X148-9N | IC1 |
Questions
What parts does the Dot projector use?
7 parts. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Dot projector KiCad files?
From the bitmorse/specklesensor repository on GitHub, at the commit this page was made from: the board is hardware/dot_projector/dot_projector.kicad_pcb and its schematic hardware/belice_dot_projector/belice_dot_projector.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Dot projector design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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