©Lin Yangchen


[Engineering works in progress]



So, after mucking around for a month with the endless mechanical and optical gotchas hidden behind the impressive-looking specs of my new Radical RPL-3T polarizing microscope, I threw down the screwdrivers, sandpaper and super glue and decided to find another microscope.

I narrowed my choices to research-grade models from the 1980s as they were fine instruments, had the Soviet-era industrial look and were affordable second-hand. I settled on the Olympus BHSP for its design, quality, modularity, versatility, track record and its market dominance which has spawned extensive online documentation and repair instructions and a large supply of spare parts. The microscopy community holds it in very high regard.

I knew there won’t be no gotchas this time.

The problem was finding one. The standard-issue BH2 is common. But the BHSP, with its full complement of quantitative optical mineralogy fittings, supersized circular rotating stage with a vernier goniometer that can measure angles to a fraction of a degree, and a lamp five times more powerful, is very rare, especially in complete, working condition. Veteran geologist Gregory McHone’s “magnificent” enhanced BHSP was put (back) together from bits and pieces that took years to salvage.

I went on eBay to see if any parts were on the market. There were bits and pieces, most of them visibly in need of repair. But one listing caught my eye. An Olympus BHSP, virtually complete and in “good working condition”, was sitting in Shanghai. It was missing the power cord, but I had the same cord on my kitchen kettle.

The seller was asking a little over 10% of Olympus’ price in 1992, accounting for inflation. There were seven watchers. I quickly checked the seller’s credentials, assessed the risk and analyzed the costs and benefits, and in an hour I had my conclusion: grab it before it’s too late. I clicked Buy It Now.

 
Two Boeing 767s carried the microscope from Shanghai Pudong International Airport to Shenzhen and from Shenzhen to Singapore-Changi International. Maps and flight profiles from Flightradar24.


I didn't know the microscope was made of iron! It weighs 24 kg.

It took a long time to extricate the microscope parts which had been disassembled into separate boxes inside the main box. Each part was wrapped in waterproof plastic film and completely immobilized in its own custom-shaped cocoon of closed-cell foam. I was not expecting this from an eBay seller. Carl Hunsinger has lots of horror-comic stories of carelessly packed microscopes dying on the journey.


Avant-garde architecture.

The microscope had been given a good cleaning and a new bulb. I stuck my kettle cord into the socket, flipped the switch and it came to life. I pushed the slider all the way to 12 volts and the 100-watt lamp shone like the sun. The weak signals from my spherulites under crossed polars looked as bright as day. No more 20-watt student microscopes. I was expecting to have to do some maintenance, but when I tried the focus knobs, the condenser centering screws, the goniometer, the nosepiece, the Bertrand lens, I realized I didn’t have to fix anything.

It was hard to believe a research-grade BHSP was standing in front of me, and it came from China.


WALL-E?

The project entered the next stage—making modifications that would give the microscope unique powers on top of its already superlative capabilities.




Olympus BH2 series
technical documentation and repair manuals

Olympus BHSP
brochure | user manual




specially modified Olympus bhsp microscope
“Soviet Mir space station”

SPECIFICATIONS


Stand

BHSP-F power switch
sliding voltage control lever
red LED voltmeter
circuit breaker
field diaphragm
45 mm filter mount on field lens housing
adjustable stage block height
hand rests on each side of base

Earthed power cord
Line Tek LS-60 ICE 60320 C13 10 A 250 V female connector
Line Tek LP-61L BS-1363/A SS 145/A British and Singapore standard three-pin plug
made in Taiwan

Diascopic illumination

BHS-LSH lamphouse
B2-CLS collector lens
filter slot

ABO898 45 mm filter holder
Nikon ND0.6 (25% transmission) neutral density filter 45 mm
DB-80 clear daylight blue filter 45 mm

Philips 7724 12 V 100 W GY6.35 tungsten halogen projection lamp
luminous flux 2800 lm
colour temperature 3300 K
colour rendering index 100
life to 50% failures 2000 h
flat filament 5 × 3.1 mm
quartz bulb
temperature 900 °C


Episcopic illumination

SoundTech FC-80 220–110 V converter 80 W with thermal fuse

Olympus TGH transformer
LED voltage indicator
input 100/115 V 0.7/0.6 A 50–60 Hz AC
output 12 V DC 50 W
7 A fuse

Olympus BH2-MLSH lamphouse
built-in heat-absorbing filter
lamp centering knob

Osram 64610 HLX 12 V 50 W G6.35 tungsten halogen lamp
xenon filler gas
dimmable
luminous flux 1600 lm
colour temperature 3350 K
colour rendering index 100
lifespan 50 h
filament length 3.30 mm
filament diameter 1.6 mm

Olympus BH2-RLA vertical illuminator
tube lens (f = 180 mm) for infinity-corrected objectives
bright-field/dark-field selector pin
aperture diaphragm
filter slots

Substage condenser

BH2-POC Abbe polarizing condenser
focal length 7.2 mm–28.8 mm
NA 0.9–0.25
lever-actuated iris diaphragm with graduated scale
for 4×–100× objectives
swing-up top lens
centering screws
built-in polarizer rotatable 360° and graduated in 5° increments
adjustable 0° click stop

Stage

BH2-SRP circular 360° rotating stage 170 mm
goniometer with vernier reading to 0.1°
45° click stops starting at any position
centering screws
stage insert with 22 mm aperture
holes for stage clips and mechanical stage

centerable condensor holder with rack-and-pinion focusing

mechanical stage AH-FMP
working range 30 mm × 30 mm with top-mount controls
vernier scale to 0.1 mm
spring-loaded slide holder

Focusing

coarse adjustment knob with tension adjustment ring
fine adjustment knob graduated in 2 μm increments
upper travel limit lever

Objectives

BH2-PRE quadruple nosepiece with RMS objective mounts, three with centering screws

pair of centering wrenches for stage and nosepiece

Olympus MSPlan achromat metallurgical objective
5×/0.13
WD 21.10 mm
super wide flat field up to field number 26.5
infinity-corrected
for 180 mm mechanical tube length
parfocal distance 45 mm (DIN)
RMS thread (diameter 20.32 mm, pitch 0.706 mm; ISO 8038, DIN 58888)

Olympus MSPlan achromat metallurgical objective
10×/0.30
WD 9.00 mm or 10.20 mm (different brochures)
super wide flat field up to field number 26.5
infinity-corrected
for 180 mm mechanical tube length
parfocal distance 45 mm (DIN)
RMS thread (diameter 20.32 mm, pitch 0.706 mm; ISO 8038, DIN 58888)

Olympus MSPlan achromat metallurgical objective
50×/0.80
WD 0.47 mm
spring-loaded
super wide flat field up to field number 26.5
infinity-corrected
for 180 mm mechanical tube length
parfocal distance 45 mm (DIN)
RMS thread (diameter 20.32 mm, pitch 0.706 mm; ISO 8038, DIN 58888)

Olympus MSPlan achromat metallurgical objective
100×/0.95
WD 0.30 mm
spring-loaded
super wide flat field up to field number 26.5
infinity-corrected
for 180 mm mechanical tube length
parfocal distance 45 mm (DIN)
RMS thread (diameter 20.32 mm, pitch 0.706 mm; ISO 8038, DIN 58888)

Analyzer assembly

BH2-PA
magnification 1×
slide-out analyzer graduated in 2° increments
rotatable 180° with locking pin
20 mm × 6 mm compensator plate slot
focusable Bertrand lens in rotating turret

AH-TP530-2 λ retardation plate (530 μm)

Head

Olympus BH2-SW super widefield trinocular head
30 mm eyepiece tubes
rotatable 360°
high-transmission coated glass prism
3-step light path selector pin (100% eyepieces, 100% camera, 20/80 eyepieces/camera)
Jentzsch binocular with fixed 30° incline
automatic tube length compensation for interpupillary distance slider (53 mm–75 mm)
38 mm circular dovetail on photo chimney

Oculars

Olympus SWHK 10×
super widefield 26.5
eyepoint 15.6 mm
focal length 25.00 mm
focusing front lens

Photomicrography

anodized aluminium adapter tube from 38 mm female dovetail to Nikon bayonet F-mount

Compensating photo eyepiece NFK2.5×
low distortion
field number 21.6
focal length 50.42 mm

Novoflex adapter Nikon–Canon lens mount
exact compensation of difference in flange focal lengths
made in Germany

Canon EOS-1D X
35 mm-format full-frame 18-megapixel complementary metal–oxide–semiconductor sensor
mirror lockup

Canon RS-80N3 cable release
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