Optical Filters for Olympus BH2 Microscopes
BH2-FH Filter Holder
The BH2-FH filter holder sets on top of the field lens beneath the condenser, and provides three filter holders, for 45mm diameter filters, that may be individually swung in or out of the illumination path. The BH2-FH contains two indexing pins on the bottom surface which mate with holes on the field lens, for physical stability on the scope.
ND Filter Holder for BHS/BHSU
This heat-resistant filter holder accepts a 45mm diameter neutral density filter, and drops into a slot near the collection lens in the 100W halogen lamphouse on the rear of the BHS/BHSU scope, to position the filter in the illumination pathway.
Note that the slot in which the filter/carrier fits will reach very high temperatures when the scope is operating at maximum intensity (up to +132C as measured by the Empire of Dirt Workshop), so do not use filters which are susceptible to heat damage in the ND filter holder. Heat sensitive filters should instead be placed on top of the field lens beneath the condenser.
To prevent injury due to burns, make sure to always allow sufficient time for the filter and filter holder to cool down before removing them from the slot in the lamphouse.
KB-4 Filter
The KB-4 filter was routinely supplied with BH2 microscopes, and was widely employed to take the warm cast of tungsten/halogen lighting when the scope was used for direct viewing. The KB-4 filter is less expensive than the LBD-IF filter, which was intended to perform a similar function for photomicrography applications.
LBD-IF Filter
The LBD-IF daylight blue filter is a proper interference conversion filter intended to shift the warm color of tungsten/halogen lighting (3200K or so) to match that of daylight (5500K to 6000K), for photomicrography applications. This filter is more expensive than the KB-4 filter that was routinely supplied with BH2 scopes (which was intended for direct viewing).
For reference, the 12V/100W lamp in the BHS/BHSP/BHSU should produce 3200K at approximately 9V, whereas the 6V/20W halogen lamp in the BHT/BHTP?BHTU should produce 3200K somewhere between 5.5V to 6V.
Didymium Filter
TBD
IF-550 Filter
The IF550 phase contrast filter is a 45mm interference filter designed to pass light at 550nm, and reject other wavelengths. Since the phase plates in Olympus LB phase contrast objectives were made to provide 1/4 wavelength phase retardation at 550nm, this filter allows these objectives to provide optimal phase contrast images. It should be noted that the 43-IF550-W45 has significantly better performance than the less expensive 45G533 absorptive filter.
The interference design of the 43-IF550-W45 makes the filter appear yellow in color, rather than the expected green. The true color can be seen when looking through the filter at a white object under proper daylight.
45G533 Filter
The 45G533 phase contrast filter is a 45mm absorptive filter designed to pass light at 533nm and reject other wavelengths. Since the phase plates in Olympus LB phase contrast objectives were made to provide 1/4 wavelength phase retardation at 550nm, this filter allows these objectives to provide good phase contrast images. It should be noted that the 45G533 has inferior performance than the 43_IF550-W45 interference filter.