DART (Differential Aerosol Reflecting Telescope)

Diagram of initial board drawing:

Meghan's amended drawing (with a few less background images, and my best attempt at explaining how the system works from current knowledge):

The reference and return photodiodes will convert the light signals they receive into current; from that current, we need information about what wavelengths of light were received. From searching basic information about photodiodes, they have a response parameter (speed/time) determined by the materials out of which they are made, which affects sensitivity in different wavelength regions. For example, PIN photodiodes are faster than P-N photodiodes. 

This example PIN photodiode seems to be sensitive to IR and visible light, and has a parameter \lambda_0 which seems to indicate the wavelength range in which the photodiode operates well.

Chris' comments Oct 24: Woo Hoo! Well done! As I look at this we can just use the beamsplitter to capture the outgoing light onto a photodiode at the top. We like (and have on hand) Hamamatsu 2281 photodiodes. They mount well in standard 1-inch mounting hardware. 

Meghan response: Just to make sure I understand, the beam splitter would be placed where I have the two optical fibers magically breaking apart from one another (in the labeled place in below diagram)?

Hamamatsu 2881 photodiodes [datasheet] are silicon-based and have a relatively large photosensitive area (100 mm^2); the spectral response works great with our desired wavelength range (~450-750nm), as expected!

Tasks (10/24):

• Begin thinking about lock-in design
  • We want to deconstruct the signal received at the return photodiode with respect to the signal at the reference photodiode
  • Review lock-in notes
• Background material/reading
  • Look at some Hubble diagrams, supernova classification
  • Background reading from email!
• Figure out how to LaTeX in Wiki/set up package to do so!
  • GPT said use LaTeX syntax enclosed in '<math>' tags to TeX – workspace settings did not allow this
  • Looking through more wiki documentation it seems Confluence is in this workspace
    • GPT says: Confluence, a popular wiki software, supports LaTeX through the MathJax plugin. You can enable MathJax in Confluence to render LaTeX equations.
    • apparently, if MathJax is enabled in Confluence, things should show up as TeX if you put them in dollar signs; however, I tested this below and it did not work.
  • How to enable MathJax plugin without Confluence login?
• Come up with a project name acronym (MOAT = Monitor Of Atmospheric Transmission currently)
  • word possbilities: retroreflector, aerosol, detector, multicolor, automated, lockin, collimated, etc.

Update from Meeting (10/27):

Before spring semester begins:

• Conceptually flush out what we are trying to accomplish
• Do back of the envelope calculations and figure out what we expect numbers wise
• Get all part numbers for setup, and order all materials

Update 11/29:

Have completed readings, have a few questions. Writing Physics 95 final paper on this project, which should help me better absorb the background material!

Update 1/26:

Have switched projects to MOSS (next-generation of dome seeing measurement).