Recently, I have my interest in spectrometry relighted, and started to think about improving the spectrometer.

Now I plan to build a new version using plastic sheets instead of cardboard, and do it with better precision. Also collimating lens would be added so the spectrum can be focused sharp over wider wavelength range.

To better plan the layout the new version of spectrometer, and simply to better understand peculiarities of its operation, I created an interactive model, where many parameters can be adjusted, and results are seen right away.

The model is written in Javascript/html/css, works in web browser. Just download it to your desktop, unzip, and open included html file; best to view it at 50% scale.

It shows positions of main elements, and traces rays coming through slit, and also diffracted ones. It also shows the spectrum focused on camera sensor.

Here is the screenshot:

On the bottom is the image of spectrum. It is modelled as a series of spectral lines at regular intervals, ranging from 350 to 1050 nm, maximal range of camera sensor sensitivity.

For camera lens focal distance, the 21.6mm is used as it stated maximum zoom focal distance for Canon A490 camera.

In this model, to see how spectrum is formed without collimating lens, one should move it to the left of grating, so it has no effect on rays hitting it. This way one can see how my cardboard spectrometer works.

I hope to build actual new version in less than a month, and post progress here in further logs.