Quick start guide.
This guide will show you how to use the
basic functions of the app by analyzing the
"example_spectrum.jpg" file provided. The screenshots below are
from the program running on a Samsung Galaxy Tab 3. The spectrum
was generated by a simple spectrometer made using a tube of lip
With the menu button, select File->Load New Image
An example image has been provided, select it.
The image will come up in its own tab. The image shown is the
first order spectrum of a typical household compact florescent
You can load as many images as you want, they will all go into
their own tabs. [Multiple tabs only
available in paid version]
Display Maximums and Intensities
To find the maximums of each line touch the button Max's
You can also show the Total intensity and the Blue, Green, and
Below is the same image but only showing the color lines (pinch
You will notice that I was a little too close to the light source
when I took this picture as I saturated my colors.
Note: from the intensity diagram, you can see that there are
a number of other peaks and the maximum lines don't line up with
all of them. This is because of the default settings for
smoothing, minimum intensity, and range of consideration. The
defaults are set to find the dominant maximums. You can set this
to your preferences (see settings
in user manual for more details).
Once the maximums have been found, you can calibrate your system
in order to find the wavelengths of each line. This entails
choosing a number or maximums and telling the program what their
wavelengths are. The CFL has well known wavelengths of which you
will see the dominant ones listed.
Calibrate with the first blue line by touching this line, the
calibration window will pop up.
Choose the 405.4nm value, touch the first button and then touch
Next touch the red line and the Calibration window appears
Choose the 612.0nm value, touch the second button and then
In this case, we will only need two lines for calibration because
we have the center line included in the spectrum and I used
a diffraction grating ruled at 360 lines/mm to take the picture
(which is the default). If you did not know your diffraction
grating size, you would have to use three lines for calibration
(see calibration in the user
To set the calibration, from the main menu select Calibrate->2
Line Calibration With Center
The system is now calibrated and you will see on the bottom row
it will tell you the grating size and the angle of incidence of
the light. (If you want, you can now remove the little calibration
flags by selecting from the menu "Calibrate->Remove Calibration
Once the system has been calibrated, touching on the lines will no
longer bring up the calibration menu. If you wish to recalibrate,
choose "menu Calibrate->Remove Calibration", then you may start
the process again.
Viewing Line Wavelengths
Now that the system has been calibrated, you can see the
wavelength of any line in your spectrum (as well as a list of
elements that produce a wavelength in this range) by touching and
releasing the line. Here we chose the third line and are
showing all elements that emit at a wavelength within 0.5nm of
this. The Ion: # is the ionization level of the
element that emits here.
(Note that I have this line listed above in the calibration box as
487.7nm, so even with my simple spectrometer
we have an accuracy better than 2nm. I bet you can do even better!)
We also have an option to generate a report for the whole spectrum.
From the menu select Image->Generate Report. A pdf report for
this spectrum will be created and will try to open in your default
pdf reader. [Available only in paid version]
Of course, it's not going be that useful to only be able to
show the wavelengths of the spectrum you already know!
The idea is to load or take multiple images. Calibrate with a
known source (the CFL is a good one because it has a number of
easily distinguishable and known lines). Then you can determine
the wavelengths of all the lines from the other images you have
taken. You may either use your favorite camera and then load those
images into the program or (in the paid
version) you can use the camera function provided in
1. The camera has been tested on a Samsung
Galaxy Tab 3 running Android 4.1.2 with no issues. It also
ran well on stock Android 4.4. However, it crashed under
Samsung's modified version of 4.4 for the Galaxy. At this
point, while the matter is under investigation, consider
the camera functionality experimental which may or may not
work on your android version. [Camera
available only in paid version]
2. On some versions of android, LightSpectra and LightSpectraLITE
will not switch properly if you:
- switch apps,
- then press home,
- then press the app
To guarantee that the program switches back properly, please use
an app switcher instead.
Philip Weetman, 2014
Disclaimer [for paid version]
part of this app is based on the QT example "declarative-camera"
using QML. It is free to use provided the information below is
attached in the documentation.
LightSpectra and LightSpectraLITE are built using the open source version of Qt 5.3.1.
This version of Qt is distributed under the Lesser GNU public license reproduced below:
GNU LESSER GENERAL PUBLIC LICENSE
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Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
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