Abstract:
A low cost modifiable spectrometer was developed for use in the spectral
analysis. Light emerging from the source is f ocused using matching set of
lenses on to two adjustable slits to collimate the beam. Then it was directed
to the center of a concave mirror. The parallel light beam reflected by the
concave mirror was allowed to fall on a 600 lines/mm transmission grating
after passing through a wide slit to remove possible higher order Fraunhofer
diffraction lines. The dispersed light beam was directed through a
converging lens before it was detected by a linear photodiode sensor array
to ensure a maximum collection of li ght falls on the detector. The linear
photodiode sensor TSL1406R was interfaced to Arduino platform. A
software application was developed to display a plot of Intensity versus
corresponding pixel number on the computer screen while saving data to a
text fi le. Standard light sources of Cadmium, Mercury, Sodium, and laser
light were used to calibrate the spectrometer. After the calibration, a light
spectrum from a Compact Florescent Lamp (CFL) was analyzed and found
that the emission lines of the spectrum are in good agreement with their
standard values up to a nanometer. Working spectral range is 398~755 nm
and the observed spectral resolution for two neighboring CFL lines is 3.8
nm. The signal to noise ratio is about 30.2 for the laser peaked at 660.79 nm
an d the total construction cost is approximately Rs.12000 for the
spectrometer.
