I'm not completely sure what you are looking for, but I built a spectrometer a
few years ago in an attempt to tweak a 4-color LED to imitate different light
sources (sunlight, incandescent, etc).
What I've got: 1. A hacked 80's (?) vintage manual spectrophotometer. I
removed the cuvette holder and light source. It's got a photomultiplier with 5V
output, a grating monochrometer in a light-tight metal box with fixed exit
and entrance slits. 2. I added gearing and a bit-banged stepper motor drive
to scan a spectrum (~280 - 800 nM). 3. It's controlled it with an ATMega328
which controls the LED's, drives the stepper, reads the PMT and sends ADC
values to host PC over serial. I've got some Python GUI code to control the
spectrometer, display a spectrum and/or save data to a file.
Problems: 1. Haven't looked at it in a while (but I still have the firmware)
2. The controller circuitry is on a breadboard. Need to remove/clean-up the
LED control stuff.
Anyway, I might be willing to collaborate. Any interest?
Rick [email protected]
From: Jerry Biehler <[email protected]>
To: "A discussion list for dorkbot-pdx (portland, or)"
<[email protected]>
Sent: Thursday, May 21, 2015 10:27 AM
Subject: Re: [dorkbotpdx-blabber] In Case You Did Not Have Anything Planned
This Long Weekend, Here Is Something To Do!!!
What I want is pretty simple, I am looking at more metrology than analysis, I
want to use it to measure transmission and reflection of thin films to make
dielectric bandpass filters and mirrors. I really could use sub-nm resolution
which I should be able to get out of this spectrometer and which is a little
tougher to do on the CCD units. Plus with a PMT you dont need to worry about
cooling or noise quite as much.
I am using a Hamamatsu HC120 PMT module like this, only the window is on the
large face, not the end:
http://www.digchip.com/datasheets/parts/datasheet/190/HC120-01-pdf.php
So my idea of it working is it would make two scans, the first would be to
adjust the gain. As it would scan it would watch for the ADC getting maxed out
and then lower the high voltage on the PMT through the HV control lead until it
is within scale. Once it passes through the scan it would scan again at that
voltage setting.
For the data, I dont care so much. It could just be CSV and dump it into excel
or sheets. But if it could be made into a compatible dataset for the other
spectrometer projects out there then this could be useful for more people.
I also have one of these monochromators that this guy used to make a
spectrometer with. https://www.youtube.com/watch?v=veETVeEsaNM&feature=youtu.be
I was hoping he would post the code but he never did.
I dont think you will get far with a PIN diode. There are detectors out there
to replace SiLi, the Silicon Drift Detectors, but they are still
thermoelectrically cooled and $$$. I can get 50L of LN2 for about $20 so that
works fine for me.
http://www.thermoscientific.com/content/dam/tfs/ATG/CAD/CAD%20Documents/Application%20&%20Technical%20Notes/Microanalysis%20and%20Electron%20Microscopy/TN52342_E_0512M_SiliconDrift_H.pdf
I live in Beaverton by nike.
-Jerry
> On May 21, 2015, at 12:43 AM, Nathan McCorkle <[email protected]> wrote:
>
> On Wed, May 20, 2015 at 1:57 PM, Jerry Biehler <[email protected]>
> wrote:
>> Would anyone be interested in helping me build a controller for a
>> spectrometer? I have a Spex 1681B, it is pretty simple, step/direction
>> pulses control the scan with limit switches and then an analog signal from
>> the photomultiplier tube. Hardware I can do, software, not so much. Figure
>> use one of their edisons.
>>
>> http://www.horiba.com/fileadmin/uploads/Scientific/Documents/OSD/1681340E340S.pdf
>>
>> -Jerry
>>
>
> I'd be up for helping you out, but I can't this weekend... too much
> going on. What did you have in mind other than telling your hardware
> to scan the monochromator and (presumably) grab ADC readings?
>
> I had been working on this a while ago, for the CCD array spectrometer
> I was working on... but I didn't have much direction other than for
> data collection and doing pH experiments (I was in a chemistry class
> at the time I started writing the software):
> https://github.com/nmz787/open-spectrometer/tree/master/desktop-software
>
> Plotting the data is achievable with many different solutions, and
> since writing the above code, I feel matplotlib isn't a great choice.
> It looks OK, but not amazing, and I've heard the library isn't
> particularly well written, and I know it's not great to try embedding
> into other GUIs.
>
> There's also Public Lab's Spectral Workbench, but I don't really know
> what it can and can't do... I feel like it's pretty tied into their
> spectrometer, and I don't know if they have things like beer-lambert
> calculations built in.
>
>
> What really interests me is some kind of machine learning on spectral
> data, to match a given spectrum to a library of data. This is where
> the big money spectroscopy companies shine, and what really
> differentiates them compared to other hardware producers.
>
>
> Anyway, I want to get together with you to talk
> SEM/High-Voltage--low-noise stuff sometime anyway. I've been thinking
> of a way to do EDX too, but using a PIN photodiode instead of a SiLi
> detector. In theory it should work, but with less resolution, and I'm
> guessing probably less signal-to-noise (so would require long scan
> times, another guess). I was planning on using an LPC4370 with it's
> 80MHz ADC on it... but not sure that will be enough bits, and it's a
> good amount of work to get up and running (I only started about a year
> ago and then got busy and distracted with how hard it was to really
> get some steam up with it).
>
> I'm out in Hillsboro most of the time, if you're ever out this way,
> drop me a line.
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