UV - vis Spectroscopy with the WheeTrometer -- page under development ---
In 2021, we decided to switch to a different microcontroller than we had been using. Prior to this change, we were embedding a Texas Instruments TM4C123 microcontroller programmed in the Code Composer Studio. We are now developing a shield for 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.
The WheeTrometer is a miniature uv-vis spectrometer with a crossed Czerny-Turner configuration. It uses a Toshiba TCD1304 CCD detector. Light dispersion incorporates a 1200 line/mm reflection grating with a 500 nm blaze angle. Our optical slits have a 0.1 mm width. Spectra shown on this page was collected using an early spectrometer with 12 bit intensity resolution and the wavelength resolution in the 1-5 nm range. The WheeTrometer Teensy Shield incorporates a 16 bit Analog to Digital Converter (ADC), giving 16 fold finer resolution.
The screen shot below shows the spectrum of a compact fluorescent lamp recorded with a 2019 WheeTrometer prototype.
The body and other structural parts of the spectrometer can be printed using a standard 3D printer.
Sample holder: We plan to offer two sample holder configurations: one for standard 1 cm cuvettes and a second, Z-configuration flow cell. Each will screw directly to the spectrometer body, just outside the slit.
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 sources: Not fully developed. We intend to offer different versions of the spectrometer that will employ different light sources. We are currently working on a uv-vis spectrometer and light source that will interface 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 will offer an optics kit containing the mirrors, slit and grating. We currently offer an electronics kit with the 2019 12 bit resolution microcontroller board. 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: 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. We hope to provide the UV-vis light source for $1000 USD.