Testing the infrared viewing system
The infrared viewing system allows the experiment to be monitored visually both prior to and during experiments. It is an important supplement to viewing through the microscope eyepieces as it allows the experimenter to see the precise region of interest being monitored by the photodetectors, without interfering with the fluorescence signals. It incorporates several of the items already detailed, but is best tested in its entirety. Correct operation should be verified, with the photomultiplier(s) switched off or disconnected, as follows:
- Connect the full detection assembly to the microscope with the CCD camera and monitor connected and switched on.
- Install the 715nm or 780nm long pass infrared illumination filter in the microscope, leaving it so that it is not in the light path.
N.B. The filter should fit into either a sliding or rotating assembly in the transmitted light path so that it can be easily removed when viewing through the eyepieces.- Focus a typical test sample (e.g. some unloaded cells) using the eyepieces.
- Reinsert the infrared filter and divert the light path to the photometric output port using the appropriate lever or dial on the microscope.
- Adjust the illumination level of the microscope light source until the diaphragm blades and the image of the test object are clearly visible on the monitor.
- The microscope should require only minimal readjustment to attain best focus on the CCD camera. If significant refocussing is needed or if the object and diaphragm are not parfocal then please consult with us.
- The field of view on the monitor will probably be more restricted than that viewed through the eyepieces. If however a suitably sized object cannot be "framed" properly on the monitor then please let us know.
- Verify the opening and closing, rotation, and lateral movement of the rectangular diaphragm. If the blades are dirty the diaphragm should be removed from its holder by releasing the two knurled grubscrews normally used for rotation. The blades can then be cleaned using a pressurised air jet or a matchstick. There may be slight imperfections on the edges of the diaphragm blades, even after cleaning. These will not affect its performance.
