Eppendorf AF2200 Plate Reader - Manual (Page 20)

Product description
Eppendorf
® PlateReader AF2200
English (EN)
20
2.6.1 Light source system
The absorbance light source system is similar to the upper fluorescence system (see p. 16).
Absorbance filter
For absorbance applications, optical band-pass filters are required to enable suitable wavelengths to pass
through and to filter the rest of the flash lamp spectrum. The filters are mounted in removable slides.
For absorbance measurements, filters with relatively narrow bandwidths (2 – 10 nm) and steep slopes are
required.
2.6.2 Absorbance optics
The mirror carriage has an absorbance position. Two small apertures create a light beam which is narrow
and more strongly collimated than with fluorescence excitation.
Light that is focussed through the dispensed liquid will be slightly refracted at the transitions between air,
liquid and the plate bottom. To achieve a reliable measurement even with a sample that is not flat, a convex
lens bundles the light beams, which may have been deflected too far from the optical axis.
The spot diameter of the absorbance light beam is 0.5 mm.
2.6.3 Absorbance detection
A silicon photodiode is used to measure the light beam. It is sensitive across a wide range of wavelengths
and is suitable for light intensities that occur with absorbance measurements up to 4 OD.
Use the Eppendorf μPlate G0.5 for absorbance measurements with smaller volumes (2 μL).