5. Optical System
88
Instructions for Use for
infinite® 200
No. 30017581 Rev. No. 1.4
2008-07
5.6.1
Light Source System
The absorbance light source system is similar to the fluorescence top system.
Please refer to 5.2.1 Light Source System.
Band Pass Filter
In absorbance applications, optical filters of band pass type are necessary to
select the useful wavelengths from the flash lamp spectrum. Filters are mounted
in removable slides.
Absorbance
Filter
Absorbance measurements require relatively narrow band pass filters (2 – 10 nm)
with steep slopes.
5.6.2
Absorbance Optics
The mirror carriage has an absorbance position. A pair of small orifices forms a
narrow and more collimated light beam when compared with fluorescence
excitation.
Light focused through the dispensed liquid is slightly refracted at the interfaces
between air, liquid, and plate bottom. To accomplish a reliable measurement in
the presence of the meniscus, a focusing lens recollects the rays of light, which
might have been refracted too far away from the optical axis.
The spot size of the absorbance light beam is 0.5 mm (diameter).
5.6.3
Absorbance Detection
A silicon photodiode is used for the measurement of the light beam. It is sensitive
to a wide range of wavelengths. The photodiode is well suited for the light levels
being encountered with absorbance measurements up to 3 OD.
Note
For absorbance measurement of nucleic acids
of small volumes (2µl) use Tecans’s NanoQuant Plate
TM
.
With this device it is possible to measure
16 different samples in one measurement.
For further information please contact
your local Tecan distributor or visit: www.tecan.com
