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Home made optics

We are working to help further develop a low cost spectrometer design that was published online by B. Hickman. To support this work, we are developing simple methods to make reflective optics.

The figure to the left shows a screenshot of a parabolic reflector designed using Sketchup. We wrote a Ruby script that generates the 3D mesh for the reflector (let me know if you would like the script for this). We exported this model as a STL file and printed copies in ABS and PLA. The plastic copies are wet sanded with 180 grit sandpaper and a couple of different reflective surfaces have been applied. Our first attempts used aluminum duct tape, which goes on easily and readily conforms to the curved surface. We have, however, had limited success at achieving a high quality polished surface using this material. I think the problem is that duct tape is made from the cheapest possible metal. My guess is that they just melt down anything in the recycle bin and that there is stuff in there that is not ever going to give a good shine. For our next attempt, we are using aluminum flashing and securing it to the 3D printed plastic model using contact cement. This seems like it will give a higher quality reflector but this material has limitations as well. To start off, it is much thicker and thus is harder to work with. While you can cut duct tape with razors and scissors, flashing requires metal cutting shears. It will also not accept a compound curve (such as the one in the figure) and is prone to leaving a sharp edge. For the spectrometer, it is not entirely necessary to use a compound curve since we can incorporate separate mirrors to focus in different dimensions. To achieve a reflective surface, we first wet sanded the surface with 1000 grit sand paper, then 1500 grit. After that, we polish with toothpaste, then with an automotive polish. We have not refined this method yet and have a number of automotive finish products to try.

Of course, having a compound curve has advantages and we have other options to explore. We have some reflective mylar on order and I will let you know how that fares. I have a feeling that it will work well for visible light, but that it will not be a good reflector for either UV or IR.

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August 2020:

  Work during summer 2020 focused on the WheeTrometer spectrometer and on the WheeStat potentiostat.

  The spectrometer is coming along.  We are currently working to improve the intensity resolution by adopting a high resolution analog to digital converter.

  Our work on the WheeStat is focused mostly on increasing the current output available.  In addition, we hope to increase the range of frequencies that can be obtained by adding a digital to analog converter.

August, 2017:

   Work during summer 2017 focused on two projects, the WheeStat potentiostat and the stopped flow spectrometry apparatus.

  •    Work on the WheeStat included changes to the user interface, firmware and hardware.  The newest version of the user interface, WheeStat6.0c, has a new zoom feature and a few bugs from the older interface have been fixed.  We believe the new hardware will be out by the end of 2017.  The new hardware will have an improved method for turning off applied voltatage between experiments.  This is a hardware fix that requires modification of the firmware as well.  We will offer an add-on for our earlier hardware versions that incorporates this feature.  Addditional changes include increased current ranges and the potential for significantly increased scan rates.

  • Work on the stopped flow spectrometry project focused on increasing the injection speed.  Our initial effort focused on developing a rack and pinnion drive for the syringes.  This improved injection speed relative to the lead screw drive but failed to meet target speeds due, we believe, to limited torque provided by the small NEMA 17 motors we chose.  Our next attempt employed larger NEMA 23 motors.  These have significantly higher torque.  Unfortunately, our flow cell was unable to contain the generated pressure and began leaking.  Current efforts are focused on developing a lab-built UV-vis cell that will hold higher pressures.


September, 2016:

  • Our work to automate solid phase synthesis of peptides / DNA, etc has progressed well, although the chemistry is more involved that I had origianally thought.  We have made our first attempt at synthesis of a cystiene modified tri-peptide

  • Our application for recognition by the IRS as tax exempt under 501(c)3 has been approved.

  • We have begun work on a low cost visible spectrometer that will use home built reflective optics.

  • We are working on developing a stopped flow kinetics instrument based on commercially avialable spectrometer.  Our current prototype is able to acquire spectra within 120 ms of mixing.  This dead time appears to be limited by the power of the motors we used.  We are investigating the use of larger motors and hope to get the dead time down to below 12 ms.






Presentation  in Atlanta, GA,  March 6-10, 2016

Our talk was well recieved at the Educational symposium at PittCon


4989 Tilley Creek Road

Cullowhee, NC 28723

Tel: 828-293-7781


Mail:  summers@wcu.edu


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Oct 23-27, SouthEast Regional Meeting of the American Chemical Society, Columbia SC

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