I think Matlab Home (not for academic or commercial use) is unbelievable value for the money.
I am not a programmer, I came to Matlab five years ago - because my spreadsheets were getting too unwieldy - via open source Octave, which I left quickly because it required a little too much hacking to keep running. Matlab was like coming home for me: it just worked out of the box and I was up and running in a couple of hours. Intuitive professional package, nicely integrated IDE, huge knowledge base, someone else has almost always run into a similar problem to yours and come up with a solution over the last 30+ years
I consider Matlab Home, the very reasonably priced full fledged version for non professional/academic use, the deal of the century. If you go that way youāll probably also want the Image Processing Toolkit.
I agree that Matlab is convenient. (I am curious what your install size is.) On the other hand, spreadsheets and Octave are powerful but you would have to eke out the potential.
The āProgram FIles/MATLABā folder for the version I am currently using (R2018B) uses 4.43GB of disk space, including Image Processing Toolbox, Optimization Toolbox and MinGW Compiler support.
Itād be good to know how repeatable is this process. Iād also like to collect SSF data for more cameras. If you do take on the build, just keep safety in mind; the two power tools needed are relatively safe, but there are always ways of malign lurking to bite you. I need to add a safety warning to the instructionsā¦
For sure, Iāll be careful, thanks for the advice
I already have the required power tools and know how to handle them.
As a good European, Iāll have first to convert your measures in metric one and then try to find the furniture in local stores (or at least in stores that deliver in EU).
A small questions about the building process, maybe I missed it, but where does the 34 degrees angle comes from ? As I understand it, it comes from the diffraction grating specifications. If you have a 1200lines/mm does the angle change?
The angle for a 1200lines/mm grating would be 42 degrees.
Scroll back up to the first post for a supporting description. Itās around the animated GIF of the diffraction, essentially that angle produces a symmetric distribution of the spectrum around the mid-point wavelength of our concern, which is about 555nm.
This occurred to me as i wrote the instructions, but I donāt know what kind of equivalent wood is available in your neck of the woods. Let me know what you come up with, and iāll rev the instructions to include them.
By the way, the critical measurement is the incident light angle we just discussed, next is probably the 12" length which has to do with how close the camera lens is to focus on the slit. After that, itās mostly TLAR: That Looks About Rightā¦
Iāve only once found a case where Matlab had any significant benefit for my uses over Octave - it was because a particular tool written by another employee at my company who chose to use Matlab used a function still not reimplemented in Octave.
However, that tool was a nightmare to maintain and I eventually rewrote the entire damn thing in Python in the span of two weeks.
numpy + pandas + matplotlib is pretty powerful too, and easier to hook in to other Python components
The primary consideration is the tool that most facilitates your work. Iāll pay for a good tool, if need beā¦
What I find as a programmer is that most of the investigative tools make quick work of figuring out a problem, but sometimes data types and/or algorithms then require significant work to translate correctly to the āproduction environmentā, which for me is now C++ā¦ (used to be Pascal, but where did that goā¦? )
For those of you looking to move to a new numerical computing language, Iād suggest taking a look at Julia. Itās a real pleasure to program in, and extremely fast too.
If youāre building the box, I need to recommend consideration of a small change. The camera is focused on the distance to the slit, and that 12" length may not be long enough to accommodate your lensā min focus distance. Now, that min focus distance is measured from the focal plane, so take that into account.
My Z6 with the 24-70 f4 min focus distance is 0.3m, so I have a few cm to play with. However my D7000 with the 18-140 is 0.45m, so with that Iām right at the slit-focal plane distance. Time to pull out the macro lensā¦
That was one of my intentions. I currently have an old Nikon D90 with an all round 18-200mm lens. But the focus distance of that one is ~45cm (18in), and unfortunately, I donāt have a better lens (Iām planning to switch to a Z6 in the coming months ).
I was also thinking about modifying the build to allow multiple lengths. Or even borrow Lego bricks from my kids to build the box.
Do you know if the inner color of the box could change the results ?
The light from the slit will reflect on the walls, hence the baffle. Painting the walls with flat black paint doesnāt help; it still reflects, but the baffle mostly takes care of it.
Iāve not painted the latest boxes; it seems that if you can get a clean spectrum surrounded by black, you can have bits of light around the edges of the image. I still try to minimize it, as a bright green pixel somewhere will vex the search algorithm in tiff2specdata.
I did my D50 with the 18-200, and I got a profile with max cc24 DE of 1.8. Iām looking at the lens as part of the optical chain to be characterized.
Iāve considered making the diffuser/slit positioning variable, just keep in mind you really need a port on the end that wonāt leak light. Thatās why my second design made the ends cover the entire box, including the lid. My first box end didnāt do that, and I spent all sorts of time trying to patch it so it wouldnāt leakā¦
We have a box of Lego āorphansā, bricks and parts that have been separated from their kit. I almost tried that, but I donāt own the contents of that boxā¦
Thanks for reading this far; if youāre going to build something, make sure you also read this:
And, somewhere in all this I posted instructions on how to build the spectroscope that works a lot better than the original one described in this thread. Here 'tis:
One of the design considerations for the new model was simplicity of construction; I got the use of power tools down to a radial arm saw and a drill. Please be sure you operate these machines safely, including getting some instruction from an experienced individual if you havenāt used either before.
The above post has links to all four posts in the series.