©Lin Yangchen

I acquired from a Chinese electronics dealer a BH2-MA-2 epi-illuminator for my Olympus BHSP. The extra-long tube lens assembly had two optical elements or groups instead of the single unit on the BH2-MA.

Complete disassembly of the BH2-MA-2 for cleaning and anti-reflective flocking.

Adjusting the filter slot with a spirit level.

The field diaphragm.

Setting the polarizing filter to the crossed position in my 3D-printed filter holder using the calibrated stage and eyepiece graticule crosshairs and a toothpick. The filter was then secured using tiny blobs of Nano Magic Tape, which has strong and immediate adhesion without curing and is easy to remove with no residue.

My modified filter holder design (cad file download) alongside the larger Olympus original. The former is more elegant, the edges of the rectangular finger tab being flush with the circumference of the illumination tube. The modified holders were forged in nylon PA12 using multi jet fusion in a huge oven that took 24 hours to heat up. The finished product sheds black particles when rubbed but costs only a few dollars. Other manufacturing methods should be used for moving components subject to frequent dynamic friction.

Full power on both illumination systems. The TGH, epitome of the industrial era, weighs a few kilograms and has a big scalloped knob that you can easily grab and turn without taking your eyes off the eyepieces, although best practice is to maintain the lamp's rated voltage.
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