on chip spectrometer?

Possibly. I'd like to see a bit more of the specifications and light intensity it requires before I take that press release at face value.

There is a bit more here but the main article is behind a paywall :(

On a sunny day (Sun, 23 Oct 2022 09:13:53 +0100) it happened Martin Brown <'''newspam'''@nonad.co.uk> wrote in <tj2t42$1jlg$ snipped-for-privacy@gioia.aioe.org>:

I see. Well, CCD sensor with prism in front of it should work too?

The best super high resolution systems use an echelle method modest dispersion prism one way and a very high dispersion grating at almost 90 degrees to it so as to map a linear spectrum onto a 2D rectangular CCD.

That example was actually observed with a Fourier transform method and then displayed in the fashion of a traditional echelle spectrum. It is a very impressive piece of kit even it it only works on bright stars:

This is a real physical highres echelle spectroscope

They are seriously nice pieces of kit. PE did an atomic absorption/emission spectroscope using a similar configuration and early CCDs back in the 1990's. Must have been ~95 because I saw it in Japan at one of the big analytical trade fairs where we were also exhibiting.

I've always wanted a handheld DVM-like spectrometer that covers a wide range, specifically 1600 to 300 nm to verify LED and laser wavelengths.

The spectrometer business seems to be a race for resolution in narrow bands. There's no wide-range low-resolution stuff that we can find.

Something like a grating and a bunch of detectors could work. It would have a lot of wavelength overlap confusion which could be mostly computed out.

On a sunny day (Sun, 23 Oct 2022 08:10:42 -0700) it happened John Larkin snipped-for-privacy@highlandSNIPMEtechnology.com wrote in snipped-for-privacy@4ax.com:

That should not be difficult to make

In the UNI we had small spectrometers that consisted of a rotating prism and a photocell looking at it through a slot (to look at a spectral line) A 'white' light source and a tube with the stuff that had to be investigated in the light beam. Big knob on top to rotate the prism, the knob had a scale with numbers on it, the wavelength. Small box, 3x3 inch or so I think. Had to repair one once. You could perhaps use a rotating prism, a slot and a photocell, tune for maximum and read the rotation from the knob?

try this one Martin

The challenge is to make a spectrometer with a wide wavelength range. It would at least need several detectors, and a prism or grating that would work over about a 5:1 wavelength range.

Nobody seems to make one.

We're lucky in electronics. We can easily measure resistance and capacitance and frequency over million or billion or sometimes trillion-to-one spans.

Our Keysight counter can measure picoseconds to kiloseconds, microHz to gigahertz.

A Fluke DVM can measure microvolts and kilovolts.

I can measure femtofarads to kilofarads with the gear on my little workbench.

On a sunny day (Sun, 23 Oct 2022 09:58:18 -0700) it happened John Larkin snipped-for-privacy@highlandSNIPMEtechnology.com wrote in snipped-for-privacy@4ax.com:

If you a need wide range IR detector:

20 THz to 150 GHz 15 to 2000 um I have a cryocooler also workbench size. You have a very strong signal using laser output, should make things easier.

Or you could perhaps use reference LEDs or laser diodes and go for interference in some crystal. non-linearity is your friend :-)

I want a spectrometer. We don't need quantified power measurement but it would be nice.

We buy all sorts of lasers and LEDs and we can't be sure they are the right wavelength. Even 1% wavelength resolution would be plenty.

Nobody makes it.

I don't know what 'all sorts' means, but for red visible and most IR, a silicon photodiode is a good detector. A grating (those start at a dollar or so) and a protractor will complete the ensemble. You already have a milliammeter, I trust.

A metal ruler is a good enough grating to measure the wavelength of a red HeNe laser.

For really wide bandwidth, you'd want a chopper and do photoacoustic detection, with a reflective grating (about $100 at Edmund ).

What the market mainly offers, is calibrated spectrum analyzers (i.e. overkill for a test setup).

[snip}

would this work? Handheld, ca. $1500,

One can cobble something together with a replica grating and a silicon photo detector array of some kind.

.

This is one example. There are many others.

You will need a calibration source of some kind. A neon tube or the like, to provide some known lines for reference.

Joe Gwinn

If we're talking thousands of dollars, I'd look at Ocean ST VIS Microspectrometers:

.

Their larger units have wider acceptance ranges, typically two bands, (like VIZ _and_ NIR) versus just one (VIS _or_ NIR).

Joe Gwinn

"Don't be a jerk. Nobody likes jerks."

That covers the visible, which would check the colors of LEDs, which is not really much of a problem.

The more serious problem is that we buy a bunch of lasers in the 800 to 1550 sort of range and we'd like to make sure they are right.

How wide a spectral range can a grating cover before things get ambiguous?

I was thinking that a grating could fire into several detectors, each with a different spectral range, and the resulting confusion might be sorted out in software.

Huh? If you just want to distinguish 850 from 1350 nm, that's no problem. The $1 replica that looks like a 35mm slide will do it fine. You can worry about blaze angles and UV transmission (the slide is a transparency, but not to UV) and line spacing fineries, but why?

Or, you could swing a detector over a range of angles and register a 'hit'. It'll take only seconds, why bother with a computer analysis?

I don't think a grating will cast a wavelenght-linear unambiguous image over a wide spectral range, like 5:1 or so.

I think the 700 nm lines will wind up on top of the 1400's. And probably much worse.

"The diffracted beams of different colors and corresponding to consecutive orders can overlap, this phenomenon becomes more likely to grow in the order of diffraction."