That about covers it. One note, this preoceedure will move the wavelength range the unit scans, but will not alter it. To cover a wider chunk of spectrum, the grating will have to be changed the one with fewer or more lp/mm.
Also you can look for light leaks by shining a flashlight at the unit while watching the display,. A light leak will raise the noise floor across the spectrum. -John ================= > My extreme curiosity eventually led me to acquire a couple ofHR2000 > spectrometers from Roland. He still has several left, and if you ever > want to > have the chance to grab one of these, I recommend you act fast. > > The units he has were from a medical diagnostic device and have a grating > which > gives about 200 nm of range. The internal sensor is specified to operate > over > the range of 200 to 1100 nm. My units were adjusted to work over the > range of > about 467 to 671 nm. Should you need it, Ocean Optics will gladly (for > IIRC > around $500) put a different grating in, or for somewhat less, change the > range > of the existing grating. > > I needed to be able to cover the wavelength of a Blu-ray laser at around > 405 nm > so decided to attempt a recalibration. I was able to download the manual > as > well as their OOIBase32 software which talks to the spectrometer over USB. > I > got a couple of USB adapters so I could plug the units directly into the > computer's standard ports. > > On the side of the unit you will notice a circular slotted pattern with a > center > screw slot and two screws 180 degrees apart on the circle. Those outer > screws > have lockwashers and each had a dab of glue. From the manual it was clear > that > this is the holder of the grating. I loosened the outer screws, and while > the > spectrometer's input fiber was pointed at the 405 nm laser spot, I slowly > turned > the center slot with a screwdriver. It didn't take much turning (CCW) > before I > saw a strong response peak. I moved it to sufficiently within the range > and > tightened the two outer screws. > > Now I turned to Appendix A in the HR2000 manual. I had to locate a Hg > lamp (I > was able to find an antique scientific unit on feebay) as you will need > several > strong spectral lines within your range for the cal procedure. I actually > cheated slightly from the procedure, I made an educated guesstimate of the > short > wavelength being seen and loaded that into the unit with the USBprogrammer > utility. That made it a little easier for me to identify the Hg lines. > > Read the procedure all the way through and understand it before trying it. > Less > hair pulled out that way. I followed the instructions, did the linear > regression as they specified in Excel (yes, an old version will work just > fine), > and loaded the correction factors into the unit's EEPROM (again, using > USBprogrammer). > > I then plugged both my units in at the same time, and if you get > SprectaSuite > from Roland (he usually sends it on a CD) and you have multiple units, you > will > see both of their responses superimposed. I pointed both fibers at the HG > lamp > (no, I didn't look into an unfiltered lamp!) and where the units ranges > overlapped, the spectral lines coincided precisely. I could have gotten a > larger range, but for now I have two units with a combined range of about > 370 to > 670 nm. I'm just not sure which end I want to expand another 100 nm. > > The procedure overall is not that difficult, and I got it right on the > first > try, but you MUST have a source of a multitude of spectral lines! The > good part > is that you don't have to open the unit up, so no chance of getting any > dust > inside. > > One note: theu nits have a mulitpin connector on one of the edges. I > found > that ambient light was getting in and raising the overall "dark" floor. > The > cure was simply to place a piece of black vinyl electrician's tape over > the > connector, flush with the case. > > Any questions, feel free to contact me off-list. > > Peter > > P.S., John, please forward to the microscopes group. I joined the > Tekscopes > group and ended up with a mountain of scopes, and the time-nuts group and > now > have a pile of time measurement and standards stuff, so no way I'm joining > the > microscopes group. I have just one, and it's crappy but works, and I'll > just > stop right there while I can still afford rent. > > > > On 1/23/2012 10:32 AM, J. Forster wrote: >> I've been bombarded with emails about retuning the spectrometers. I'll >> get >> the info and repost it in the near future, unless Peter would prefer to >> put it up himself. >> >> Best, >> >> -John >> >> ============== >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> >> ----- >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 10.0.1416 / Virus Database: 2109/4760 - Release Date: 01/22/12 >> >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
