[time-nuts] HR2000 Retuning

Tue Jan 24 01:33:45 UTC 2012

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
>>
>> ==============
>>
>>
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