A UV-Visible-IR Spectrometer
The i-Phos HD spectrometeter, by Chris Wesley, is a ready-made version
of the Theremino spectrometer, with the option of a single 1mm slit, or
a set of interchangeable slits. 3D-printed PLA slits are available in widths of 0.5, 1, 2, 3, 4 and 5 mm.
Metal slits in PLA frames are also now available in widths of 50, 100, 200 and 500 μm. The
wavelength range is from about 360 nm (near UV) to 1150 nn (IR), with
some fall-off at the extremes. Resolution achievable with a 1mm
slit is around 1 nm.
The diffraction grating in the i-Phos is a piece taken from an unused 4.7 GiB DVD-R disc. The rulings
in that case have a spacing of 0.74 μm, gving about 1350 lines/mm.
Here we adapt the i-Phos by removing the supplied 1 mm slit and attaching a Frederiksen
symmetrically-adjustable slit assembly. As supplied, the Frederiksen slit gives a continuous
adjustment range from about 100 μm to 6 mm, and the minimum aperture can be reduced by careful adjustment of the slit-blade holder. The exact setting is easily
determined by measuring across the outside of the blade holder (using a dial caliper) and subtracting a fixed amount.
[Article under construction].
Fusion 360 CAD rendering of a 3D-printable mount, for attachment of a Frederiksen symmetric
adjustable slit assembly to the i-Phos spectrometer. Orange colour is for visualisation only. Final print, in ABS, is black.
Design by Stephen Knight.
i-Phos HD Spectrometer
building a standard definition version.
Standard 640 × 480 manual-exposure webcam is no longer available, so a dedicated 1920 × 1080 full HD camera module is now used.
a DIY Spectrometer
[Creative Lab] YouTube Video.
(please support this open-source facility).
Theremino Spectrometer Construction.
Theremino Spectrometer, Sample Spectra.
Help file (instructions) is
in the zip file.
I finally obtained a Frederiksen adjustable slit from Timstar
(WF Education Group) but it took 4 months on back order before I got
it. Still, I suspect that Timstar deserves praise for getting it for me
at all, because when I went back to the Frederiksen Scientific site to
give a link to it, the item seemed to have disappeared from their
It is a beautiful piece of precision engineering.
Making something similar is not beyond the capability of a good
engineering workshop, but certainly not a trivial undertaking.
Ovio Instruments - Frederiksen slit.
Public Lab, spectrometer FAQ