• Predominantly experimental week
  • Observed Vega and Beta Lyrae taking a spectrum scan of each
  • Another attempt at calibrating the spectrometer
Calibrating Spectrometer
  • Initial thoughts are: the artificially introduced offset on the micrometer isn't large enough therefore the grating is not rotated enough.

  • Plot for left hand peak of Cadmium at 6.50mm showing horizontal smearing:
    unfocused.png

  • Diagram of the spectrometer and setup:
    spectrometer.png
  • Lateral magnification (w') given by:
\begin{equation} w'=w\frac{\cos(\beta)}{\cos(\alpha)}\frac{f_2}{f_1} \, , \end{equation}
  • where α and β are the angles of the light in the spectrometer and f1 and f2 are focal lengths
  • Change in the angle with respect to change in wavelength due to different orders of diffraction under small angle approximation:
\begin{equation} \frac{d \theta}{d \lambda} = \frac{n}{d} \end{equation}

  • Plot for cadmium before adjustment of grating:
    AlignedB.png

  • Plot for Cadmium at 6.50mm after adjustment to the grating:
    Aligned.png
First Vega Analysis
  • Spectrum of Vega at 06.50mm:
    Vega.png

  • Normalised plot of Vega at 06.50mm and its second derivative:
    Norm_Vega_0650_Der2.png

  • Vega plot at 06.50mm with peak finder algorithm:
    Peaks.png
-- JamesAngthopo and Will Burrows - 11 Nov 2016
Attachments Attachments
Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng Aligned.png r1 manage 126.6 K 11 Nov 2016 - 11:49 JamesAngthopo Plot for Cadmium at 6.50mm after adjusment to the grating
PNGpng AlignedB.png r1 manage 74.5 K 11 Nov 2016 - 11:45 JamesAngthopo Plot for cadmium before adjusment of grating
PNGpng Norm_Vega_0650_Der2.png r1 manage 68.3 K 11 Nov 2016 - 12:30 JamesAngthopo Normalised plot of Vega at 06.50mm and its second derivative
PNGpng Peaks.png r1 manage 58.5 K 11 Nov 2016 - 12:29 JamesAngthopo Vega plot at 06.50mm with peak finder algorithm
PNGpng Vega.png r1 manage 145.4 K 11 Nov 2016 - 12:32 JamesAngthopo Spectrum of Vega at 06.80mm
PNGpng spectrometer.png r1 manage 37.5 K 11 Nov 2016 - 11:21 JamesAngthopo Diagram of the spectrometer
PNGpng unfocused.png r1 manage 124.2 K 11 Nov 2016 - 11:47 JamesAngthopo Plot for left hand peak of Cadmium at 6.50mm showing horiztonal smearing
Edit | Attach | Watch | Print version | History: r3 < r2 < r1 | Backlinks | Raw View | Raw edit | More topic actions

Physics Webpages • RHUL Webpages • Campus Connect • Royal Holloway, University of London, Egham, Surrey TW20 0EX; Tel/Fax +44 (0)1784 434455/437520

Topic revision: r3 - 25 Nov 2016 - JamesAngthopo

 
This site is powered by the TWiki collaboration platform Powered by PerlCopyright © 2008-2024 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding RHUL Physics Department TWiki? Send feedback