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Introduction to UV - vis Spectroscopy with the WheeTrometer

The WheeTrometer is a customizable spectrometer capable of measuring light in the UV and visible regions.  It uses the Toshiba TCD 1304 charge coupled device as a detector and incorporates a Teensy 4.0 microcontroller development board programmed in the user friendly Arduino development environment.

An introduction to the Wheetrometer project is provided the video below.  This video was recorded for presentation to a 2022 science conference that moved online. 

     The WheeTrometer is a miniature uv-vis spectrometer with a crossed Czerny-Turner configuration.  The hardware and software for this instrument are open-source.  We are dedicated to making it as easy as possible for the user to design and build a spectrometer to their own specifications. Light dispersion with a 600 line/mm reflection grating and a 75 mm focal length focusing mirror gives a spectrometer that will cover ~250 to 750 nm range.  Our optical slits have a 0.1 mm width.  The WheeTrometer Teensy Shield incorporates a 16 bit Analog to Digital Converter (ADC).

     In 2021, we decided to switch from using a Texas Instruments TM4C123 microcontroller to the Teensy 4.0 microcontroller development board. The change was made for a few reasons, most importantly to allow users to hack and upload their own firmware using the familiar Arduino environment. 

Software:  We are working to optimize and improve the user interface and firmware.  In 2021 we undertook a  renovation of our approach to the hardware and that meant new firmware.  While we were at it, we began a updating some of the user interface and that meant backing out and re-tooling some of the stuff we had working.  This is all work in progress, so please bear with us.  We are committed to getting this right and creating the most intuitive and useful user experience possible.


Right now, our user interface (GUI) will do the following tasks:

  •   connect automatically to the spectrometer over USB.

  •   set run parameters such as integration time, etc.

  •   initiate spectral acquisition

  •   display recorded data

  •   save data files in csv format

  •   acquire multiple data files

  •   conversion of raw intensity to absorbance

We had a number of other features working that we screwed up in our updates.  We don't foresee major obstacles doing this but it all takes a little time. We plan to get the following features back in the user interface:

  • import saved spectra,

  • mathmatic manipulation of spectra.  

Light sources: Our spectrometer can be used with commercial light sources or you can build your own. We offer hardware for interfacing the Wheetrometer via standard SMA905 fiber optic connectors. We also plan to develop instruments where the source connects directly to the spectrometer.  Our UV-vis light source will employ deuterium and halogen lamps.  A dedicated visible spectrometer may be developed that relies on leds as light source.


Availability:  Kits are currently available.  We offer an optics kit containing the mirrors, slit and grating and a Teensy 4.0 based electronics kit with the 16 bit ADC.  Supplies are limited and shipping delays are a real possibility if we need to reorder.  We originally ordered fifty circuit boards and we will re-stock once those are sold.  The microcontroller will come with the firmware installed.  User interface will be available from our download page or on usb drive.  STL files for 3D printed plastics will be available.  I will consider printing parts, but that is not a service I plan to get deeply into.

Costs:  We offer the spectrometer as a set of kits for considerably less than the price of other available spectrometers.  Our combined spectrometer kit (containing both optics and electronics) is available for $250 USD.  Alternatively, we can provide either the electronics or optics kits separately.  Contact me for a quote.

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