Yet Another Scanning Monochromator Build - Page 1
Forum section: electronics / testgear

author: AlphZeta
author_rank: Regular Contributor
timestamp: August 17, 2015, 12:10:08 am
content: OK, I just got a Verity EP200Mmd monochromator from eBay. It is similar to the one Shahriar had down a teardown and modification with earlier.I decided to take a different approach and not to modify the monochromator itself.Code is posted on my website:http://www.kerrywong.com/2015/08/16/yet-another-scanning-monochromator-build/

author: KE5FX
author_rank: Super Contributor
timestamp: August 17, 2015, 07:12:17 am
content: I have one of these with the stepper motor that I want to get up and running one of these days. It has the EP200SCR fiber-optic coupler but I haven't run across any cables that interface with it. Has anyone successfully ordered 100- or 200-cm silica-clad cables from Verity, or gotten a quote for them? Any other good sources for cheap fiber cables, integrating spheres, and the like? eBay is letting me down bigtime here.

author: AlphZeta
author_rank: Regular Contributor
timestamp: August 17, 2015, 12:00:27 pm
content: You might want to check with Shahriar to see what he used as the cable (his might have come with the cable though) as his has the fiber optic input as well.

author: AlphZeta
author_rank: Regular Contributor
timestamp: August 18, 2015, 03:54:37 pm
content: BTW, if anyone knows what causes the peaks in the infrared region in the spectrum for incandescent lights in my experiments, please leave a comment. Thanks!

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 18, 2015, 04:23:22 pm
content: I love Monochromator!Here is mine with some accompanying measurements:Teardown, Upgrade and Experiments with a Verity Visible Wavelength Monochromatorhttps://youtu.be/veETVeEsaNM

author: KE5FX
author_rank: Super Contributor
timestamp: October 19, 2015, 06:53:03 pm
content: Quote from: AlphZeta on August 18, 2015, 03:54:37 pmI just got my EP200Msd up and running, with an Arduino-based USB interface to drive the stepper motor and read the data. Looking at a flashlight bulb, it seems that I'm also seeing a strong IR peak in about the same place. But I'd also note that I get a lot of variation in the shape of the spectrum depending on how the lamp is positioned relative to the slit. (I still don't have a lens or any other proper optical coupler.)Same bulb, same voltage, but different bulb positions, and different HV levels between 200-400V. (The display shows the current value at the time the image was saved, not the value it was taken with.)These plots are corrected for the R928 PMT response, so they will look a bit stronger in the IR region for that reason alone.

author: AlphZeta
author_rank: Regular Contributor
timestamp: October 19, 2015, 07:38:00 pm
content: Nice plot! The observed spectrum will be different if the location of the lamp is different, especially when the lamp is very close to the slit. Ideally, you want uniform illumination on the slit (e.g. diffused light or far field light).

author: KE5FX
author_rank: Super Contributor
timestamp: October 19, 2015, 10:03:28 pm
content: Yes, after some further trials it's clear that positioning the light source close to the input slit is a Very Bad Idea. I've emailed Verity to see if they'll sell me a fiber cable that plugs into the EP200SCR coupler.I tried a couple of Toslink cables, and while they can be clamped into the EP200SCR and will deliver light to the input port, they really wreck the flatness of the spectrum. Lots of attenuation below 480 nm. The longer cable (25') also caused a deep notch at 615 nm, which I didn't expect.