Author Topic: An Encounter with a Surgical Operating Microscope.  (Read 983 times)

Offline Pete W.

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An Encounter with a Surgical Operating Microscope.
« on: August 11, 2018, 02:49:13 PM »
A friend of the family who is a Veterinary Surgeon had the opportunity to acquire a used surgical operating microscope.  (He didn't tell me what he paid and I didn't ask!!)  Knowing of my interest in microscopes, he asked me if I would give it 'the once over' and fix anything that needed attention.  I agreed to try it.

The microscope is a Zeiss Op-MI6 and dates from the 1960s.  It is about 80 inches high and has, so far, defeated my attempts to take a clear photograph.  I'd hoped to open this thread with a photo of the whole thing but that will have to wait until a later post - in the meantime, Googling 'Zeiss Op-Mi6' will bring up many photos of members of the Op-Mi6 family, similar to but none identical to the particular version concerned here.

The requirement that sets surgical operating microscopes apart from 'ordinary' microscopes is that, once he/she is scrubbed-up for the surgery, they cannot touch the microscope controls by hand.  So the microscope motions are moved by electric motors controlled by foot-switches on what is termed a 'Pedal Unit'.

Here is a link to a .pdf file describing the history and development of Zeiss Operating Microscopes: http://www.microscopy-uk.org.uk/mag/artdec12/fs-Zeiss-Operating-Microscopes-1.pdf.  That was Part 1, here's the link to Part 2:  https://www.microscopy-uk.org.uk/mag/artjan13/fs-Operating-Microscopes-2.pdf

I'll finish this post with a random photograph and continue my introduction in a second post.
 
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Pete W.

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Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #1 on: August 11, 2018, 03:09:43 PM »
The Op-Mi6 consists of a heavy base with three lockable castors and a central foot-operated brake.  The base contains a 'splitter' for the incoming AC mains supply.  The base supports a vertical column some 80" high.  This column is tubular and guides the carriage that supports the actual microscope head on a pivoted arm.  The strong plastic ribbon is attached to the carriage and runs in a groove in the column up to its top-cap where it is directed into the interior of the tube where either a weight or a long spring counter-balances the weight of the microscope, arm and carriage.  (See the Google photos to get the idea - I'll take and post some photos of this particular unit as soon as I can.)

There are two boxes mounted on the column below the lower limit of motion of the carriage.  One of these contains the power supply for the microscope lamp while the other contains the power supply for the motions of the microscope.  I call this box the 'Control Unit' - it bears some switches affecting the microscope functions and several connectors, acting as the junction box connecting to the Pedal Unit and to the microscope head.  Each of these two boxes has an IEC connector to accept mains power from the 'splitter' in the base.

Here's another random photograph:
 
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Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline nrml

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #2 on: August 11, 2018, 04:40:07 PM »
It's interesting that none of the modern surgical microscopes at work have foot controls. They just cover all the handles and buttons with a sterile clear polythene bag type thing with a lens orifice built into it.

The difference might because of the plethora of foot pedals for various other operating theatre devices like diathermy, phacoemulsifiers, xray machines etc etc. It is amazing how the availability of cheap plastic sheets (something we now take for granted) has changed the way machines are built.

Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #3 on: August 11, 2018, 04:55:44 PM »
Hi there, nrml,

Thank you for your post - it's interesting.

As I wrote in my opening post, this Op-Mi6 dates from the 1960s.  I guess that in the fifty plus years since then surgical techniques would have to have moved on.  I'm not in the surgery business so I'm just posting in the context of the instrument before me.

A neighbour recently had her gall bladder removed and just had five small keyholes in her back to show for it.  I understand that the surgeon's hands didn't actually touch the patient - just the controls of what might be termed a hi-tech manipulator!

Might you post a photo (or photos) of the instruments with which you come in to contact?  I'd welcome that. 
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline nrml

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #4 on: August 12, 2018, 07:46:30 AM »
I'll try to get some pictures of the microscopes at work when they are in use next. It's a bit tricky if there are other members of staff or patients in the operating theatre. Everyone seems to be paranoid about confidentiality these days even if they are not anywhere remotely in the picture frame.

Actually on thinking about it, it is very likely that foot pedal controls are an optional accessory that we didn't buy.

Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #5 on: August 13, 2018, 12:47:46 PM »
Well, I managed to get set up and take some photos of the complete microscope (except that the Pedal Unit got cropped out!

 
« Last Edit: August 13, 2018, 02:11:23 PM by Pete W. »
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Pete W.

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Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #6 on: August 13, 2018, 02:04:56 PM »
An essential first step in any refurbish exercise is to perform a survey.

The photos in the previous post show the base and column, the carriage and microscope head and the control unit and the power supply for the lamp.  The Control Unit is the upper of the two boxes clamped to the lower part of the column.

When received, the outlet shroud on one of the connectors that mate with the Control Unit was broken and the metal part of that connector was bent out of line.  This was the connector on the cable from the microscope head.  It has five poles (i.e. male contacts).  One pole was a ground and I speculated that the other four were devoted to the focus motion (one pair) and to the zoom motion (the remaining pair).  However, exploring with the ohm-meter only found one pair, raising the spectre of broken wires or open circuit motors.  It would have been a great help if I'd had matching female contacts with which to tip my meter test leads, trying to reliably contact one pin at a time in a connector shell only 13 mm in diameter was a challenge!  The first photo shows this connector as received.

Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline awemawson

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #7 on: August 13, 2018, 02:22:16 PM »
So Pete when are you installing the Theatre Light and scrubbing up  :lol:

(an end view of that plug would help in identification)
Andrew Mawson
East Sussex

Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #8 on: August 13, 2018, 02:39:39 PM »
I gave the lamp power supply a functional test.  It has a mains power input with fuses and two double-pole sockets on its top face and a four position control knob and two lamps, green & red (maybe LEDs), on its front face.  The double-pole sockets are for the output power to the lamp (6 Volts at 30 Watts).  The four switch positions give 'Off' and three levels of lamp excitation - in position #4, the green light is extinguished and the red light comes on.  This is because position #4 over-runs the lamp bulb to give the right colour temperature for photography but at the expense of bulb life.  (There is no camera with this Op-Mi6.)

I then removed the Control Unit from the column and removed its back-plate.

I took a look at its contents (see the first photo), gulped and moved on to the Pedal Unit.   :bugeye:   :jaw:   :bugeye:   :jaw: 

The exterior of the Pedal Unit didn't reveal much so I partially dismantled it.

Step #1 is to turn the Pedal Unit upside down and remove two M4 cap-head screws and washers from their recesses on the unit centre-line.  As received, one of these was missing.

Step #2 is to withdraw the pivot rod for the rockers, now no longer secured by the two screws of step #1.  The end of the pivot rod is accessible through a hole in the end of the housing cover.

Step #3:  Turn the unit right-side up - the two rockers can now be removed.  This reveals the plungers of the six switches protruding through holes in the cover.

Step #4:  The cover is secured to the base casting by four blind tubular nuts on the upper surface and four more M4 cap-head screws and washers in recesses in the underside of the unit.

The second and third photos respectively show the Pedal Unit as received and with the rockers and cover removed.
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #9 on: August 13, 2018, 02:53:27 PM »
So Pete when are you installing the Theatre Light and scrubbing up  :lol:

(an end view of that plug would help in identification)


Hi there, Andrew,

Funny you should mention theatre lights!  In order to get the illumination for the photos of the complete instrument, I had to commision a 400W halogen work-light, on telescopic pylon.  I bought it some time ago, I can't remember whether it came from MSC or from CPC.  The halogen tube came un-fitted and, inevitably, I touched it with my fingers while inserting it into the lamp-holder.  I washed it off with VCR head-cleaning fluid.  I bounced the light off the ceiling which seemed to avoid shadows.

There's a small crack in the quartz tube so I ordered a couple of replacements from RS, just in case!   :zap:   :zap:   :zap: 

This microscope has been dominating our living room since March!  The photography required that I clear the mantelshelf so I could anchor the top of the background bedsheet.

My lovely but shy assistant has been OK with it so far but I know the job is on borrowed time.   :hammer:   :wack:   :hammer:   :wack: 
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #10 on: August 13, 2018, 02:57:54 PM »
Andrew, I didn't reply to your point about the connector.

It's an obsolete German component.  I haven't been able to identify it.

I have some more photos of it dismantled but they come later in the saga!!

As near as I can tell, the contacts are close to size 16.

There will now be a pause in my postings while I attempt to produce a tidy and legible circuit diagram (aka 'schematic') of the Control Unit. 
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline awemawson

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #11 on: August 13, 2018, 03:36:31 PM »
The reason I mention it is because I think that I recognise it as being the same as on one of my Heidenhain touch probes, or at least the same series.

I managed to source a suitable socket for it a few years back but can't find any photos to confirm
Andrew Mawson
East Sussex

Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #12 on: August 13, 2018, 03:58:02 PM »
Hi there, again, Andrew,

Here's another photo of the connector.

The half-shell fits on to the main part of the connector and is retained by a very slim thrust washer and by the screw-jacking collar.  Then the outlet shroud screws onto the threaded portion of the connector body, in the process securing the flexible strain relief tail.

That thread is 0.7 mm pitch (or maybe 0.75 mm pitch, I forget).  The original outlet shroud is a moulding which I couldn't duplicate.  So I turned up a new shroud from a piece of acrylic, that seemed the most suitable of the materials available to me.  I'd never turned an internal thread before, I took it slowly and it fits quite well considering the male threaded part of the metal connector body is bent out of line!  It's neat but not gaudy!!!

That connector is five-way - the connector that's on the cable from the Pedal Unit is a twelve-way.  That was OK but I'll be writing some more about that cable in a later post. 
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Online PeterE

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #13 on: August 13, 2018, 04:08:03 PM »
To my eyes it looks very much like a standard DIN-connector. An older version of this f ex. https://www.ecvv.com/product/4569845.html

BR

/Peter
Always at the edge of my abilities, too often beyond ;-)

Offline awemawson

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #14 on: August 13, 2018, 04:27:18 PM »
Sadly not the one that I had in mind, which was far better engineered and cost a fortune !
Andrew Mawson
East Sussex

Offline nrml

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #15 on: August 13, 2018, 07:47:45 PM »
That is an interesting little microscope. Very compact and quite unusual in that it seems to have only one set of eyepieces. Most of them tend to have two sets of eyepieces so that an assistant or trainee can help with the operation or view the procedure. Most modern ones have an inbuilt camera in addition to the two sets of eyepieces which gets fed to an external monitor.


Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #16 on: August 14, 2018, 07:38:19 AM »
That is an interesting little microscope. Very compact and quite unusual in that it seems to have only one set of eyepieces. Most of them tend to have two sets of eyepieces so that an assistant or trainee can help with the operation or view the procedure. Most modern ones have an inbuilt camera in addition to the two sets of eyepieces which gets fed to an external monitor.


In my opening post, I suggested typing 'Zeiss Op-Mi6' into Google and going to the photos offered there.  Among those photos there are many showing other variants of the Op-Mi6 including lots with multiple sets of eyepieces.

On the one I have here there is a dummy beam-splitter sandwiched between the eyepieces and the main body of the microscope head.  This one is just there to maintain the correct optical path length (aka 'tube length') but it could have been replaced by a functional beam-splitter and one or two additional sets of eyepieces.  I used the past tense because Zeiss ceased to support the Op-Mi6 a long time ago!!

My first job was with EMI Ltd.  One of their departments developed a colour television system.  It didn't win the competition for the broadcast market so they had a go at the surgical training sector.  It was reported of the inaugural trial that when the surgeon made his initial incision both the camera operator and the guy at the vision mixer panel in the OB van outside fainted and were caught by porters stationed by the surgeon for just that purpose!!  (They might not have been porters.) 
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Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #17 on: August 27, 2018, 09:29:26 AM »
I'm going to digress a bit but it's all in support of the theme of the thread!

I'm a gadget junkie.  When my main hobby was SCUBA diving, I had much more equipment than matched the few hours per year I spent underwater.  Similarly, when my main hobby was amateur radio, I had much more equipment than was justified by the time I spent on the air.

Having some awareness of my addiction to gadgets, I've spent my life deliberately avoiding 'taking up' photography - I knew once the camera bug bit me I'd be bankrupt overnight!!  I did buy a digital camera (stills) when I set up my eBay account but I'm not 'into' DSLRs and, until now, definitely not 'into' video.

Despite that, I did buy a cheap digital camcorder a couple of years ago to record an outdoor social event and achieved results that were good enough.  The camcorder is totally unbranded, no maker's name or model number.  It will take either still photos or video and records onto an SD card.  It just says 16 MegaPixels.

Now, how does all that relate to the surgical microscope?  Well, although I've recorded some of the project with still photos, the aim of the project is to restore the operation of the focus and zoom motions in response to the rockers on the Pedal Unit.  Can't show that very well in still photos!  So, I thought that when I've developed this thread account a bit more, it would be appropriate to show those motions in a video to illustrate the fruit of the project.

So I set up the camera and a light source before the microscope stand and had a couple of attempts to show the focus and zoom motions in operation.  Both takes were very fuzzy and out of focus.  I was filming from a couple of feet distance.  For the first take, I had the camera set with the 'focus' switch set to the mountains icon and for the second take I set it to the tulip icon.  It didn't seem to make much difference to the sharpness of the video image.

If I unscrew the decorative aluminium ring around the lens, there is a male thread of 30 mm diameter.  Does that correspond to a standard thread for attachment of filters and/or close-up lenses?  Should I be looking for a close-up lens?
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Pete W.

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Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #18 on: September 01, 2018, 12:36:20 PM »
Since my last post, I've got a different camcorder.  Hopefully, I'll be able to capture the video 'footage' I referred to.  But there's a lot to tell before that!

I explored the circuitry of the Pedal Unit but it wasn't making sense without the Control & Power Supply Unit so I turned my attention back to that.  The first photo shows the innards of the Control & Power Supply Unit as received.  The second photo shows most of the schematic of that unit.  The parts omitted are the connections between the various power supply lines and the 12-way connector to the Pedal Unit and the connections between that connector and the 5-way connector to the Microscope Head.  They will be shown on sheet 2 of the schematic (to follow later).  Some of the circuitry on sheet 1 is a bit speculative - the reason is that the components are so closely packed into the box that visual access is impossible!

I have used Fast Stone Resizer on the schematic but I chose a bigger size than our usual value - if it's too big when I see it uploaded, I'll change it.

Most of the C & PSU circuitry is straightforward.  Zeiss have chosen to fuse both legs of the mains supply input.  I wouldn't have designed it that way but this post is showing what I received.  All the metal parts of the C & PSU are bonded to each other and to mains earth and both the 12-way and the 5-way sockets provide a contact to bond to the metal parts of the Pedal Unit and the Microscope Head, pillar etc.

The two transformer secondaries each feed a bridge rectifier arranged to provide a symmetrical DC output.  Secondary 'A' includes a tap selector switch to select one of two available output voltages.  The switch concerned here is the one whose dolly is labelled 'Focus I II'.  Secondary 'B' does not have this facility.  The 'B' output rails each have a mystery component in series.  These each measure 01Ω, they might be self-healing fuses of varistors.  I was surprised to find that neither set of output lines is connected to ground.

The numbers in circles refer to the transformer secondary tag panel.  References to 'Tag #8 & #9' and similar refer to the tag-strip that runs parallel to the edge of the box.  I arbitrarily allocated numbers to the tags starting with #1 at the left-hand end (with the green/yellow wire).  The two 'mystery components' can be seen mounted on the tag strip on the opposite side of the box.

My schematic drawing complies with no known standard but I hope you will be able to understand it.  I grew up when resistors were shown as zig-zag lines and transformer windings were loopy but I agree that those styles take skill and time to depict well.   
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Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #19 on: September 22, 2018, 03:16:02 PM »
The parts of the circuit of the Control & Power Supply Unit shown in sheet 1 of the schematic (see previous post) were fairly easy to trace, partly by visual examination and partly using my Fluke multimeter.  The parts of the circuit comprising the interconnections between the various connectors were more difficult, since much of the wiring was in the depths of the housing, inaccessible to both Fluke test probes and Mk1 eyeball.  In fact, the space was so densely packed that there was no access even for my dental mirror.  Consequently, some of the connections shown on Sheet 2 of the schematic are inferred and there may even be connections that are not shown at all.  The fact that I was able eventually to achieve both focus and zoom operation of the microscope head depends on the 'P/FZ' switch remaining in the 'P' position and the focus and zoom connectors remaining unused.  (The particular microscope head in this instrument is wired to connect to the 'P' connector.)

The 'Focus I II' switch is partly beneath the upper tag-strip in the photo included in the previous post - the 'FZ/P' switch is partly beneath the lower tag-strip.

In my next post, I expect to describe my tussle with the Pedal Unit microscope head. 
« Last Edit: September 22, 2018, 03:57:44 PM by Pete W. »
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Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #20 on: October 15, 2018, 06:13:32 AM »
 :offtopic:   :offtopic:   :offtopic: 

Well, folks have been viewing this thread despite my lack of input!  I apologise for my lack of posts, due to two factors:

One:  whenever I logon here I've been absorbed by Andrew's adventure with his CNC lathe, and

Two:  I've been distracted by a problem with the family car!  The flange on the handle of the oil-level dip-stick has embrittled with age and one or more fragments of it have fallen down the dip-stick tube.

I bought a bore-scope, its head is 5.5 mm in diameter and has six LEDs on its face, surrounding the camera.  It plugs into the USB socket of a smart phone or lap-top.  It cost about 6 and came in a smart cardboard box with clear plastic windows - I fail to see how anyone could produce just that box and get it from China to the UK for 6, never mind the contents!!!!!!
It works impressively well out in the open.  The problem was that it's been coiled up in the box for so long that I couldn't get the head to lie axially in the dip-stick tube so,
it didn't yield the pictorial evidence for which I was hoping.   :bang:   :bang:   :bang: 
The next gambit was to buy a 24" long 'grabber' with a flexi stem.  It has four claws that come out of its head when the knob is operated and even has three button cells and an illuminating LED.
However, it's head was too big a diameter to fit down the dip-stick tube!!!   :bang:   :bang:   :bang:

I'm awaiting delivery of a slimmer grabber and I hope to return to the surgical microscope saga when the dip-stick problem is resolved.   
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline awemawson

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #21 on: October 15, 2018, 09:26:35 AM »
Oi, don't blame ME young Pete  :lol:
Andrew Mawson
East Sussex

Offline Pete W.

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Re: An Encounter with a Surgical Operating Microscope.
« Reply #22 on: October 15, 2018, 11:48:24 AM »
Oi, don't blame ME young Pete  :lol:


Well, it wasn't just you - Steve's bridge-building account was in there too!   :lol:  :lol:  :lol: 
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!