Hi Shalin

NPL/HSE resolution test slide is for either dark field or phase contrast
microscopy

The UK's NPL laboratory originally made the NPL/HSE phase contrast
resolution slide. You focused onto the slide and a series of lines appeared.
The smallest one you could see was naturally the best Ph resolution at that
magnification. I bought mine back in the late 1980s/early 1990s, but
recently I've not seen them about that much [my old NPL phase slide is now
lost since our labs at Harwell folded].

http://annhyg.oxfordjournals.org/cgi/reprint/28/2/237.pdf
says it all about the slide

A while ago I had trouble locating one, but I see it's about again and easy
to obtain, e.g.
http://www.zefon.com/store/hse-npl-phase-shift-test-slide.html

and details are on NPL's website:
http://www.npl.co.uk/reference/faqs/what-is-an-npl-hse-test-slide-and-where-
can-i-obtain-one-(faq-length)

We used the slide as we were heavily involved in asbestos and glass fibre
durability/toxicology studies, and it's pretty essential for asbestos
monitoring to ensure your microscope is up to detecting the fibres.

Regards

Keith

---------------------------------------------------------------------------
Dr Keith J. Morris,
Molecular Cytogenetics and Microscopy Core,
Laboratory 00/069 and 00/070,
The Wellcome Trust Centre for Human Genetics,
Roosevelt Drive,
Oxford  OX3 7BN,
United Kingdom.

Telephone:  +44 (0)1865 287568
Email:  [log in to unmask]
Web-pages: http://www.well.ox.ac.uk/cytogenetics/
 
-----Original Message-----
From: Shalin Mehta [mailto:[log in to unmask]] 
Sent: 22 July 2009 07:36
To: [log in to unmask]
Subject: Re: resolution target

Hi Keith,



On Tue, Jul 21, 2009 at 8:54 PM, Keith Morris<[log in to unmask]> wrote:
> Hi Thomas,
>
> A high resolution target for what exactly? Calibration in um? Or perhaps
> phase contrast resolution?
>

I got curious that you mention phase contrast resolution target. Is
there a transparent resolution target on market whose thickness
changes at well defined intervals? Phase gratings are useful but they
do not offer benefits of things like spoke pattern.

I am involved with phase imaging and have been searching such a target
since sometime. If you can point me to some such source that will be
great. There used to be an equivalent of USAF target for phase
microscopy called Richardson test slide but the company went out of
business.

best
Shalin

mobile: +65-90694182
blog: shalin.wordpress.com

Bioimaging Lab, Block-E3A, #7-10
Div of Bioengineering, NUS Singapore 117574
website: http://www.bioeng.nus.edu.sg/optbioimaging/colin/people.asp#shalinm