SPI Instrumentation: professionally designed for scientists by scientists, more capability and less cost.
About
Have you ever felt excited about an experiment that you would do, but for access or funding to buy the instrument? In earlier times, scientists often built their instruments or worked with instrument makers. Galileo built telescopes with Lipperhey and Joule developed fantastically precise thermometers with Dancer. Nowadays, you can buy almost any sort of instrument. But they are often very expensive, effectively limiting who gets to do science and what sort of science is done. While we do not advocate polishing your own lenses as did Newton (unless you have a great idea for a new lens), we feel there is a middle ground where high-end measurements and protocols are affordable and you can assemble experiments in ways that free your imagination. This is the SPI Instrumentation project.
If you want to do top notch science with measurements that you actually understand and on a budget that is within your means, the SPI Instrumentation Project is for you. Our goal is opening access to doing more and better science for more scientists.
Here we describe a set of core instruments that you need for a laboratory. In fact, most of these have been built and refined through use in our own labs. And as open boards, the costs are very low. Think of the portion of your tab at a high end restaurant that represents the actual food. In our cafe we focus on raw capabibility. An example of one of our results, obtained synchronizing multiple modalities of measurement and control, is displayed here.
Sponsorships, donations
and custom projects:
For sponsorships for scientists, we are offering a board, the one that you sponsor, and for early sponsors, another board when we have sales or donations sufficient to produce boards in modest quantites. Making boards one or two at a time, assembly charges are actually more than parts! So sponsorship is important to help us get past build to order and make these important tools available for the scientific community at a great price and hopefully enable a lot of great science.
Please contact me and indicate which board (or boards) you would like to sponsor. And of course for donations, any amount is helpful.
If you would like us to do a custom project for you, or if you have any questions about the boards here, please write me at The Instrument Maker c/o Dr Nelson's Lab.
And again, please don't forget to DONATE
The Instrumentation Boards
- Voltage and current
- Single photon detection and tagging
- Light and position, spectrometer detectors
- Light intensity
- Power supply, MCU Carrier
Instrumentation Input
Instrumentation amplifier input (InAmp),
selectable gain and impedance (100K, 10M, ~100G),
voltage noise density 5nV/√Hz, current noise density 4fA/√Hz,
differential 16 bit 1MSPS ADC,
SPI interface.
InAmps are important for precise and sensitive voltage measurements in a wide range of applications from semiconductor research to brainwave monitoring, for their very high impedance, very low offset, very low drift, very low noise and very high common mode noise rejection.
Current to voltage amplifier
Current to voltage amplifier with selectable gain from 100 to 10M V/A, small size lets you place this close to your study object,
the input is a virtual ground,
input current noise for this opamp is 5fA/√Hz and bandwidth is configured to 160KHz.
Inquire for custom configurations.
Waveform and voltage output
Digital to analog output, 16 bit, DC to 1MSPS, range -4V to +4V, slew 800V/μs. From the datasheet, "drives all capacitive loads". Compatible with the Instrumenation Input for simultaenous waveform generation and measurement.
High voltage high current amplifier
Output boost compatible with the waveform and voltage output. Maximum output 0 to 50V or -25V to +25V. Nominal settings are gain x5 and current limit 0.5A. Please contact us for custom configurations.
Silicon Photomultiplier amplifier, discriminator, time to digial converter
Photon tagging (counting and recording the arrival time of individual photons) is important in fluorescence lifetime measurements, and also in a range of quantum optics studies. The board comprises an amplifier, comparator and time to digital conversion to count and measure the arrival time of photons as detected by the silicon photomultiplier. The precision is 55ps. Controls are provided for threshold and hysteresis. The connector labeled "start" is an input that carries the signal to start the timing interval. "Stop" is an output that mirrors the pulse detection signal.
Silicon Photomultiplier detector
Silicon photomultipliers (SiPM) are single photon detection devices and can be used for sub-nanosecond timing of photon arrival. This detector has a fast 1.5ns pulse output with a rise time of about 100ps and can operate at temperatures down to -40C. The board has a thermistor mounted adjacent to the SiPM and can accept a sealed cover on the face and a thermoelectric cooler on the back behind the sensor.
Linear CCD (TCD1340)
Linear CCD sensor board using the Toshiba TCD1304 with a low noise analog section and 16bit 1MSPS ADC.
The Toshiba sensor is widely used in commercial spectrometers.
This is a higher performance variation on the design described in the github repository for the single board LCCD sensor device.
Here we improved the precision with a lower noise front end and as in the github version, we provide science oriented functionality in triggered and gated operating modes and kinetic series, as well as the more routine clocked functions, and we support all combinations of shutter and frame interval and data averaging.
Linear CCD (S11639-01)
Linear CCD sensor board using the Hamamatsu S11639-01 with a low noise analog section and 16bit 1MSPS ADC, similar to the design in
the TCD1304 board.
Design files and firmware are available at the github repository for the S11639-01 sensor board.
Photodiode (OPT101)
This is a photodiode detector based on the TI OPT101, sensitivity 0.45A/W at 650nm with gain configurable from 1 to 50 MV/A.
The board accepts a housing on the front (detector) side, with output and power from 2.7 to 36V on the rear.
Controller (Teensy 4.0)
This is the board that controls the instrumentation boards, coordinates and synchronizes with other boards to implement experiments with multiple devices, runs your firmware or the firwmare that we provide, and is controlled and automated by the Python or C++ class library. The board accepts a Teensy 4.0 (600MHZ ARM Cortex-M7 with 480MHZ USB) or Teensy 3.2. The 20 pin header across the top connects to the instrumentation card and carries data, control and synchronization signals. The 16 pin single row header mirrors the instrumentation interface plus it has 4 additional pins for trigger, gate, synch and a spare. The 20 pin header on the left provides 10 additional pins and grounds for analog input or digital i/o, which can be used to control other devices such as motors. There is also a precision 2.048 volt reference, and outputs to provide filtered +5V power and regulated 3.3V power.
Power supply
Precision low noise dual +5V aned -5V power for the instrumentation cards. Can be used as single or dual suppy.
TCD1304 All-in-one
All-in-one Linear CCD sensor board based on the TCD1304 with a precision front circuit and Teensy 4.0 or 3.2 microcontroller card. This has been use in courses to teach instrumentation electronics. A detailed discussion of the circuit, firmware and functionality, along with design files, a spice simulation, firmware for the T4, and host software in Python are all available at the github repository for the All-in-One Linear CCD device
Examples
Spatio-spectral Imaging
This is the evolution of the spatial and spectral distribution of light from a 1mm2 organic light emitting diode driven at 50uA/cm2. The data is recorded as a time series of spatial distributions in response to a step in voltage at each step in wavelength using a graded narrow bandpass filter mounted to a miniature motorized linear translator.
The experiment is run from a Python script that sets up a triggered kinetic series in the linear ccd, a triggered analog transient recording for current using the current to voltage amplifier and instrumentation input, and a waveform for the analog output which also generates the trigger. After signal averaging some number of frames, the controller drives a stepper motor to move to the next position and runs a temperature controller loop before begginning the next acquisition loop. The experiment runs unattended for several days to generate a complete data set over a series of currents and temperatures. We believe the approach to instrumentation described here plays an important part in making possible this level of experiment and that compared to sleepless nights and long tables handscrawled in notebooks, constructing an experiment with these kinds of tools produces more reliable and traceable results, and is a better and more educational experience for graduate students.
Spectrometer
The following is a demonstration of what you can do with modular parts. This is a spectrometer built with the TCD1304 sensor board plus a 50mm 1200ln/mm transmission grating (Thorlabs, $215), lens, slits and sma905 fitting from ebay, some 3-d printed mounts and some Al and plastic from online suppliers (Amazon, onlinemetals.com, and etc.). The case is a bit rough and there is black tape for stray reflections, but wow, look at the performance. The spectrum is from a fluorescent lamp at about 4m distance, with a 200um slit and 1m of 200um fiber to point at the light. As is apparent, signal to noise and resolution are quite good. The small commercially available spectrometers often use much smaller, less dense gratings (a 12.7mm 600ln/mm gratings is typical). They are cheaper and smaller, you will need a much smaller slit with those instruments to get the resolution you see here, and with those instruments you will need a lot more light to get to this signal to noise ratio. And of course, being designed by actual scientists, our instrument gives you trigger and gating functions that are important and not as available as perhaps they should be in commercial instruments. In other words, with a little care, you can actually put together a very competitive spectrometer for about 1/25 of what it cost to buy one that gives you less performance and less capability. Plus, the commercial instrument is propriety and they may charge you extra for software to be able to us it. The instrument here is an open design. You can have the design files, the parts list, the firmware source code, and the host software. We believe that is an important difference and even more so if you are not at a high end university with a large grant to buy the commercial instrument.
Supporting the project and getting boards for your lab
Your sponsorship or contribution is important to help make these important tools available for the scientific community and hopefully enable a lot of great science. If you have any questions or would like to obtain or sponsor a board, or have us do a custom project for you, please write me (click here).
And please help use make science more accessible, DONATE HERE