To comply with the new ISO 15189:2012 medical laboratories accreditation, Hampshire Pathology asked if we could calibrate the eyepiece graticule in their microscope. A graticule is a linear scale fitted into one eyepiece, it enables the user to convert the apparent size of a subject as seen through the eyepiece into a real world dimension.
Whenever there is a need to make measurements with an eyepiece graticule, there is also a need to ensure that the microscope is calibrated. The use of a stage micrometer to check the divisions and measurements on the eyepiece graticule is the best way to achieve this calibration.
We carried this out using a UKAS certified micrometer slide which has a finely divided scale marked on its surface. The scale is of a known true length. and provided them with a calibration certificate.
A calibration certificate was provided for each instrument calibrated and also the calibration certificate for the micrometer slide.
Anthony Nolan is a UK based charity that works in the areas of leukaemia and hematopoietic stem cell transplantation.
Anthony Nolan determine tissue types of volunteer donors to provide a match for patients who need a stem cell transplant. Microscopes are used for HLA serology Class 1 and 2 tissue typing.
The 3 microscopes used for the HLA test were using HBO 103 mercury arc UV light sources, the client wanted to reduce the cost of lamps and make the lamp set up easier.
Southern Microscopes set up one of the microscopes with a CoolLED pE-100 470nM light source. The pE-100 is a mercury-free compact and simple to use LED illumination systems which can be configured to deliver light directly to a microscope.
Its main features are:-
• Broadest LED spectrum available: 365-770nm – replaces metal halide or mercury
• Compatible with existing single and multi-band filter sets – no need to buy new filters
• Instant on/off – no shutters required, no warm up or cool down
• Simple to fit, simple to use – no alignment, a once only adjustment
• Stable & repeatable – reliable and consistent results
• Wide range of microscope adaptors – fits most microscopes
• Precise intensity control in 1% steps (0-100%) – no ND filters required
• Excellent uniformity over field of view – fixed and stable, no alignment necessary
• Long lifetime – expected to exceed 25,000 hours of operating time
After an initial one month trial Anthony Nolan agreed to purchase two pE-100 systems to replace the exsisting mercury arc systems.
The department wanted to add the ability to test for fungi using calcofluor white stain. The use of calcofluor white, a fluorescent brightener with the addition of potassium hydroxide (KOH) will enhance the visualisation of fungal elements in specimens for microscopic examination.
They already had one microscope set up to test for acid fast bacilli using auramine-phenol stain, but this was a fixed wavelength LED system that could not be adapted.
The department had an old Leitz Diaplan microscope fitted with a mercury arc fluorescent system and one filter set designed for auramine.
It was decided the most cost effective way to achieve both test was to retro-fit a CoolLed pE-300 led light source and an additional filter block to the Leitz Diaplan microscope.
The CoolLed pE-300 was specified with the following wavelengths, 400nm, 470nm and 540nm.
Chroma Technology was contacted and they were able to supply a Leitz Ploempak filter cube that would enable the calcofluor white stain to be used at the 400nm wavelength.
Once client was happy with the system configuration, all the relevant parts were ordered and the system was put together and tested.
|Example of Auramine stain||Example of Calcofluor White stain|