[RASMB] noisy interference data

[Leech, AP]

Hi Mark,

Our laser setting for all cells is about 0.7 deg duration. I think
you should go through the holes on your rotor with cells filled with
water or even sample if it's nice and clear, and adjust the delay and
duration to give nice clear fringes. I seem to recall this ought to
be done at the speed of interest, but in fact it seems to hold well
enough between 3000 and 50000 as I said before.

The duration may need adjusting for different centrepieces. We have
some Spin Analytical ones that need more careful adjustment than the
Beckman ones.

The delay setting does vary for different rotors e.g. 4-hole v 8 hole.
We aren't lush enough to have more than one of each, but I suspect it
depends on the positioning of the overspeed disk so would vary for
different rotors of the same type.

If you stick to the same rotor and cells, the settings shouldn't shift
much.

Hope this helps,

Andrew


On 24/02/2011 13:50, Mark Agacan wrote:
> I checked the laser settings as advised and found:
>
> cell 	
> laser delay 	
> laser duration 	
> exposure time
> 2 	157.1 deg
> 	
> 1.7 deg 	6.30 uS

> 4
> 	67.1 deg
> 	0.6 deg
> 	2.22 uS

> 6
> 	337.6 deg
> 	1.7 deg
> 	6.3 uS
>
> I also found this in the rasmb archives:
> "The main "gotcha" about setting the duration is that if you go too high you
> will end up with the superposition of a single-slit interference pattern
> upon the
> double-slit interference pattern. As long as you use the typical *0.5 - 0.8
> degrees for the duration* (assuming that you are NOT using the old style
> interference
> window holders) you will be fine."
> So I'm thinking to bring the laser duration for cell2 and cell6 down to
> the value of cell4. Any further advice is greatly appreciated.
> Many Thanks,
> Mark
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Dr Mark Agacan, Scientific Officer for the Division of Biological
> Chemistry and Drug Discovery,
> Wellcome Trust Biocentre, College of Life Sciences, University of
> Dundee, Dundee, DD1 5EH
> Tel: +44 1382 386095 Fax: +44 1382 345764 Mobile: 07525 451 117
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ************************************************************
> Please consider the environment. Do you really need to print this email?
>
>
>  >>> Tom Laue <Tom.Laue at unh.edu> 2/24/2011 13:05 >>>
> Hi Mark-
> The interference system requires the use of sapphire windows, except at
> very low rotor speeds.
> Modern synthetic sapphire windows may be used to 230 nm. The old
> sapphire windows were not clear much past 280 nm, but that is no longer
> an issue.
> I know that some labs have switched to using only sapphire window since
> they almost never break, and may be used with all three optical systems.
> Best wishes,
> Tom
>
> On 2/24/2011 4:37 AM, Mark Agacan wrote:
>  > Hello,
>  > I have attached a jpeg image showing recent SV interference data plots
>  > taken from sedfit.
>  > All data was collected with quartz windows as I was primarily
>  > interested in the absorbance @ 280 nm signal.
>  > IP2 and IP6 are very noisy but IP4 looks fine.
>  > Is this a calibration problem or is this related to damaged windows /
>  > centerpieces (there are no visible defects or scratches on any of the
>  > components).
>  > Many Thanks,
>  > Mark
>  > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>  > Dr Mark Agacan, Scientific Officer for the Division of Biological
>  > Chemistry and Drug Discovery,
>  > Wellcome Trust Biocentre, College of Life Sciences, University of
>  > Dundee, Dundee, DD1 5EH
>  > Tel: +44 1382 386095 Fax: +44 1382 345764 Mobile: 07525 451 117
>  > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>  > ************************************************************
>  > Please consider the environment. Do you really need to print this email?
>  >
>  > The University of Dundee is a registered Scottish charity, No: SC015096
>  >
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-- 
Dr Andrew Leech                   *  Laboratory Head
Technology Facility               *  Molecular Interactions Laboratory
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