Meopta BC28 SV
is a field microscope designed for a variety of field work. Primarily designed for military use, the housing and body were dark green, but later this "civilian" version was also created. Basically, it allows the user to observe the specimen in a light field, oblique illumination and modified dark field.
The basic optical equipment of the Meopta BC28 SV microscope are achromatic objectives with magnifications of 6, 10, 20, 45, 60 and 100×. The case also contains Huygens eyepieces with magnifications of 6, 10, 15 and 20×.
With its robust steel housing with gasket, measuring 310 × 130 × 245 mm and weighing 7.8 kg, it allows for relatively easy and safe transport.
As already mentioned, the transport case contains everything you need: lenses in screw-in cases, 4 eyepieces, a refracted monocular tube with adjustable length and two wooden organizers with a mirror, immersion oil, Canada balsam, fine brush, cloth, tweezers, slide organizer case, clamping clips for the table and a blue filter.
The microscope could be operated either with the original micrometer-sliding stage or using a pair of spring-loaded slide holders.
Under the round fixed stage is an Abbe condenser with a numerical aperture of 1.2 NA. It allows the upper lens to be removed and thus reduce its aperture (0.45NA) for weak lenses (low magnification). This condenser also allows the use of the oblique illumination method, thanks to the lateral alignment and rotation of the lower collection optics including the aperture, in addition it also has a holder for traditional 32mm filters.
In its original design, the BC28-SV microscope was developed to use a double-sided mirror for field work. The custom microscope was supplemented with a custom designed and 3D printed 8W light source including a controllable power supply. This solution can be powered in the field using a power bank with USB-A output. The light includes a top matte filter that adjusts the color temperature to a neutral 5000K. The light flow can be infinitely controlled thanks to a potentiometer. A special feature of this solution is the integrated heatsink and 40mm fan inside the console, which allows the LED chip to be actively cooled via side vents, allowing the microscope to be used for up to 3h at 40°C.
In combination with a straight monocular tube, a clamp bayonet, a projection eyepiece (Meopta FU 2.5; 4; 6.3×) and a top adapter, the microscope can also be used for microphotography. Combined with a modern digital camera and an 8W LED light source, the set-up enables dark-field microphotography up to 20× magnification.
