UV - vis Spectroscopy with the WheeTrometer
June 2019: This project is currently in the prototyping stage.
The WheeTrometer is a miniature uv-vis spectrometer with a crossed Czerny-Turner configuration. It uses a Toshiba TCD1304 CCD detector and a Texas Instruments TM4C123 microcontroller. Light dispersion incorporates a 1200 line/mm reflection grating with a 500 nm blaze angle. While the spectrum below was recorded using a home-manufactured slit with a width of ~0.6 mm, we have ordered manufacture of 0.1 mm slits for this project. The spectrometer has 12 bit intensity resolution and the wavelength resolution (with the 0.6 mm slit) is currently in the 1-5 nm range.
The screen shot below shows the spectrum of a compact fluorescent lamp recorded with the WheeTrometer.
The body of the spectrometer can be printed using a standard 3D printer. The colimating mirror is 20 mm in diameter with a focal length of 100 mm. The focusing mirror is rectangular, 20 x 50 mm with a 50 mm focal length.
Sample holder: Not yet developed. This is pretty simple and we will get to it.
Software: We are working to optimize and improve the user interface and firmware. As of June 2019 our user interface (GUI) will do the following tasks:
1. connect automatically to the spectrometer over USB.
2. set run parameters such as:
2a. integration time,
2b. number of acquisitions to average before reporting, and
2c. number of pixels to average
3. initiate spectral acquisition
4. display recorded data
5. save data files in csv format
We are now working to incorporate multi-datafile protocols, import saved spectra, conversion of data types (raw intensity to absorbance) and various math manipulations. These we have worked out in our other projects so we don't foresee any major obstacles.
Light source: Not yet developed. We intend to offer a version of the spectrometer that will interface via standard SMA905 fiber optic connectors. We are also working on a uv-vis source that connects directly to the spectrometer. This light source will employ deuterium and halogen lamps.
Availability: We anticipate making kits available by September 2019. We will offer an optics kit containing the mirrors, slit and grating. We also plan to offer an electronics kit with the microcontroller and detector boards. 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.
Costs: While it is too early to give a firm number to the price, we expect the spectrometer and light source will be considerably less expensive than other available spectrometers. Since people will want numbers, here they are (please do not hold us to these). We hope to offer a combined spectrometer kit (containing both optics and electronics) for $250 USD. We hope we will be able to supply the light source for $1000 USD.