Olympus CH-2

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Patrick
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Olympus CH-2

#1 Post by Patrick » Sun Feb 03, 2019 10:58 pm

Oldie but goodie :)

I got it from eBay, as not hard to imagine, in quite poor shape but after few hours of cleaning and proper lubrication it moves and works like a dream. Probably because I put all those hours into it I love my very first microscope to bits :D
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Of course I had to do a mod on it. No.1 - convert 6V 20W tungsten to 2W LED (I did keep the light source at the same point in space).

I was nicely surprised when seeing vast brightness improvement especially with higher magnifications, where it truly matters.

I am considering going even further with additional switch to UV illumination for the future genetic modification project but one step at a time for now.
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ChrisR
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Re: Olympus CH-2

#2 Post by ChrisR » Sun Feb 03, 2019 11:57 pm

Looks good. I have one or two - or is it four, of those all different. They do get a bit hot, don't they?!

Is the disc we can see in there something you made up? And have you reused the lamp dimming part?

Hobbyst46
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Re: Olympus CH-2

#3 Post by Hobbyst46 » Mon Feb 04, 2019 2:28 pm

Patrick wrote:...I am considering going even further with additional switch to UV illumination for the future genetic modification project...
Is the UV lamp wanted for fluorecence? anyway, I would gather and install eyesight safety features before I turn it on. Simple colored glass filters are not likely to provide adequate protection.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

ChrisR
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Re: Olympus CH-2

#4 Post by ChrisR » Mon Feb 04, 2019 4:08 pm

The UV danger is really hard to get a handle on. I suspect we worry where we needn't, but that's the right way.
Certainly the shorter UV is worse.

Recently learned that a 60W (?) light bulb puts out more UV at 365nm than a 3W nichia 365nm LED. Surprising.

I also have tested my spectacles. They're "reactolite". You can draw on the front with a 405nm laser, the coating immediately goes dark.
But you can't do that from the reverse direction. So the polycarbonate(?) absorbs it all, the reacting coating being on the front, doesn't get any. 365nm doesn't get through either. Standard g.p. School safety glasses also stop it, apparently completely.
"Luminous" plastics indicate the same, even if the UV torch torch is left shining through the safety glasses for a minute or so.

Having said that, would you want UV transmitted light? I wouldn't - it's a risk anyway. If you shone it in from the side, the fluorophores would glow just as well.

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Re: Olympus CH-2

#5 Post by Hobbyst46 » Mon Feb 04, 2019 5:52 pm

Trans-iilumination fluorescence has long been eliminated in favor of epi-illumination, mainly because it is easier then to separate the fluorescence from the immensely stronger excitation illumination. If the illumination is pure UV, however, its light is invisible to man (and camera - depending on the camera) so trans-illumination fluorescence might be a possibility. However, to do so, all optical elements up to the specimen must transmit UV, and IMHO safety should be considered - e.g. UV goggles.
If you shone it in from the side, the fluorophores would glow just as well
Agreed. But less readily done.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

desertrat
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Re: Olympus CH-2

#6 Post by desertrat » Mon Feb 04, 2019 6:01 pm

I've never really thought about trying fluorescence illumination, but was wondering if it would be possible to convert a standard illumination system using UV LEDs, and then using a dark field stop in the condenser for low power and a dedicated dark field condenser for higher powers. Would that prevent the UV excitation source from going up into the eyepieces?
Rick

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A/O 4 Series Microstar
A/O 4 Series Phasestar
A/O 4 Series Apostar
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Re: Olympus CH-2

#7 Post by Hobbyst46 » Mon Feb 04, 2019 7:14 pm

desertrat wrote:I've never really thought about trying fluorescence illumination, but was wondering if it would be possible to convert a standard illumination system using UV LEDs, and then using a dark field stop in the condenser for low power and a dedicated dark field condenser for higher powers. Would that prevent the UV excitation source from going up into the eyepieces?
Hopefully this is not too much aversion from the thread main topic, my appologies if so. neither did I try fluorescence at home, but I think I would do otherwise than trying to block UV from entering the eyepiece: I'd wear UV shielding goggles, place a black paper cylinder or similar barrier around the illumination port up to the condenser - to block sideways stray UV light - and place the emission filter between the objective and eyepieces/photo projection objective, if that is possible. That emission filter is important - it should block all UV, so intuitively should be an interference filter.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

Patrick
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Re: Olympus CH-2

#8 Post by Patrick » Mon Feb 04, 2019 10:53 pm

ChrisR wrote:Looks good. I have one or two - or is it four, of those all different. They do get a bit hot, don't they?!
Is the disc we can see in there something you made up? And have you reused the lamp dimming part?
For the radiator I used a leftover of an aluminium rod I had laying around. Its 32mm dia and 20mm in height. It is held by a single screw from underneath. I should have made some fins on it to allow better heat exchange but it doesn't get that hot. (I did briefly tested a setup with 3 LEDs but it was an overkill and in this configuration it did get toasty :) )

For the dimmer I connected the transformer to a diode bridge with 2000uF capacitor and I used a cheap LM2596 buck converter. I replaced the original multi-watt potentiometer with 1kohm to externalise it for the buck converter board. My prime objective was to introduce my changes in the way so it would be easy to roll them back if I wont like the results. The potentiometer is still driven by the original luminosity control wheel (for the ones planing to do this - the gear that mounts to the potentiometer fits on a 6mm shaft [some potentiometers are 1/4"])
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Patrick
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Re: Olympus CH-2

#9 Post by Patrick » Mon Feb 04, 2019 11:18 pm

Hobbyst46 wrote:
desertrat wrote:I've never really thought about trying fluorescence illumination, but was wondering if it would be possible to convert a standard illumination system using UV LEDs, and then using a dark field stop in the condenser for low power and a dedicated dark field condenser for higher powers. Would that prevent the UV excitation source from going up into the eyepieces?
Hopefully this is not too much aversion from the thread main topic, my appologies if so. neither did I try fluorescence at home, but I think I would do otherwise than trying to block UV from entering the eyepiece: I'd wear UV shielding goggles, place a black paper cylinder or similar barrier around the illumination port up to the condenser - to block sideways stray UV light - and place the emission filter between the objective and eyepieces/photo projection objective, if that is possible. That emission filter is important - it should block all UV, so intuitively should be an interference filter.
Thank you all for raising your concerns, comments and ideas. I'm planing to play with yeast glowing in UV. At no circumstances I am planing, or encourage anyone, to look through the eyepiece when the UV will be on. All the focussing and looking at the speciment, in the UV mode, I am planing to do via a fixed camera (if I get lucky I might even splurge on a trinocular head... but finding one, and at reasonable price, isn't easy).

I am planning to use UV LED (it's a pre-testing phase idea for now). I want to mod this so that I can switch between WhiteLight/UV modes with a flick of a switch.

The whole subject of bioluminescence is new to me but it always excited me. I will keep you posted when I get further on this path.

billbillt
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Re: Olympus CH-2

#10 Post by billbillt » Mon Feb 04, 2019 11:47 pm

Hi Patrick,

Great job converting to LED.. I am also fond of LED lighting.. I like the look of warm white vs cool white.. To me, it looks more like sunlight...

The Best,
BillT

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75RR
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Re: Olympus CH-2

#11 Post by 75RR » Tue Feb 05, 2019 4:55 am

Recently learned that a 60W (?) light bulb puts out more UV at 365nm than a 3W nichia 365nm LED. Surprising.
I'd be interested in a source for that if you have it to hand. Thanks
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Re: Olympus CH-2

#12 Post by ChrisR » Tue Feb 05, 2019 7:17 pm

This post, about 10 lines up from the bottom "2.66 stops"
So it was 100W halogen but 2.66 stops better than a 3W 365nm LED.
So all you'd need is a short pass filter over the halogen bulb. :idea:

http://www.photomacrography.net/forum/v ... 118#244118

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Re: Olympus CH-2

#13 Post by 75RR » Tue Feb 05, 2019 7:22 pm

Many thanks!
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MichaelG.
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Re: Olympus CH-2

#14 Post by MichaelG. » Tue Feb 05, 2019 8:11 pm

At the risk of stating the obvious [please forgive me, if I am]: The envelope of a 'halogen' bulb is made from quartz ... and that is why it transmits so much UV

Any following optical elements that are made of glass will significantly attenuate that UV

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Re: Olympus CH-2

#15 Post by MichaelG. » Tue Feb 05, 2019 8:57 pm

From a usually-reliable source of information:
The majority of the emitted energy (up to 85 percent) lies in the infrared and near-infrared regions of the spectrum, with 15-20 percent falling into the visible (400 to 700 nanometers), and less and 1 percent in the ultraviolet wavelengths (below 400 nanometers). The soft glass envelope of ordinary incandescent lamps absorbs most of the ultraviolet radiation generated by the tungsten filament, but the fused silica quartz envelope in tungsten-halogen lamps absorbs very little of the emitted ultraviolet light above 200 nanometers.
Ref: http://zeiss-campus.magnet.fsu.edu/arti ... #colortemp

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Re: Olympus CH-2

#16 Post by Hobbyst46 » Tue Feb 05, 2019 9:01 pm

MichaelG. wrote:From a usually-reliable source of information:
The majority of the emitted energy (up to 85 percent) lies in the infrared and near-infrared regions of the spectrum, with 15-20 percent falling into the visible (400 to 700 nanometers), and less and 1 percent in the ultraviolet wavelengths (below 400 nanometers). The soft glass envelope of ordinary incandescent lamps absorbs most of the ultraviolet radiation generated by the tungsten filament, but the fused silica quartz envelope in tungsten-halogen lamps absorbs very little of the emitted ultraviolet light above 200 nanometers.
Ref: http://zeiss-campus.magnet.fsu.edu/arti ... #colortemp

MichaelG.
I guess that laboratory halogen lamps, like the Zeiss HBO, emit a small but significant amount of UV, whereas consumer lamps, for example 100-500W home halogen bulbs, are supposed to be coated against UV or have a glass envelope that blocks UV. So, if anyone considers placing a consumer's halogen lamp in a microscope light source, that lamp may not yield UV.
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Re: Olympus CH-2

#17 Post by MichaelG. » Tue Feb 05, 2019 9:24 pm

Simple check ... If the bulb is a small capsule, and comes with a warning not to touch the surface with bare fingers when installing, then it's quartz.

The oil deposits left by touching can damage the surface when it heats up.

I think it safe to say that most 'halogen' microscope and projector bulbs come with such a warning.

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Re: Olympus CH-2

#18 Post by ChrisR » Wed Feb 06, 2019 12:38 am

The fellow inthe other thread is a full time microscopist. He measured the UV at the camera, so it's been through the same opticts as the HBO or LED light. With an Epi fluorescense illuminator the dihroic mirror & absorption filter will stop any UV getting up to the eyepiece, but with normal viewing there's nothng to stop it - other than the eyepiece.

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Re: Olympus CH-2

#19 Post by MichaelG. » Wed Feb 06, 2019 8:10 am

ChrisR wrote:... With an Epi fluorescense illuminator the dihroic mirror & absorption filter will stop any UV getting up to the eyepiece, but with normal viewing there's nothng to stop it - other than the eyepiece.
At the risk of being overly pedantic, Chris ... Assuming that by 'with normal viewing' you mean 'with transillumination' the list is rather longer: Condenser & Objective [unless specially selected] will both attenuate the UV before it reaches the eyepiece.

This is either a comfort in terms of personal safety, or a hinderance in terms of efficacy.

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Re: Olympus CH-2

#20 Post by ChrisR » Wed Feb 06, 2019 10:51 am

Pedandry is fine if it contributes!

To be clear on what I meant:

The issue here is whether there is something in the optic train to protect the user from UV.
That does happen when the traditional method for fluorescence observing is used, with its normal filters.

Otherwise, whether transillumination or epi illumination is used, there aren't any anti-UV filters.
. Much UV passes through glass.
I'm sure our reader can work out which of above/below stage condenser, objective, cover glass etc etc is used, or relevant.

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Re: Olympus CH-2

#21 Post by MichaelG. » Wed Feb 06, 2019 12:46 pm

For transmission characteristics of some typical optical materials ...
Newport has this excellent page:
https://www.newport.com/n/optical-materials

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Re: Olympus CH-2

#22 Post by ChrisR » Wed Feb 06, 2019 1:03 pm

Yes, optical crown glass passes plenty at 365nm. (Otherwise it wouldn't get through the condenser in the epi-illuminator, the tube lens and the objective.)

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Re: Olympus CH-2

#23 Post by billbillt » Wed Feb 06, 2019 2:04 pm

One of these placed over the light would help.. a simple fix...

https://www.ebay.com/itm/Filter-photo-v ... rk:12:pf:0

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Re: Olympus CH-2

#24 Post by MichaelG. » Wed Feb 06, 2019 5:25 pm

ChrisR wrote:Pedandry is fine if it contributes!

To be clear on what I meant:
... and, following your excellent example, I should make clear that I was using the word 'attenuate' literally.

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Re: Olympus CH-2

#25 Post by ChrisR » Wed Feb 06, 2019 8:06 pm

I wouldn't call 13% attenuation "significant" if I was worried about 365nm UV.
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Bill - no - short pass allows UV. So with a short pass over the light, you've attenuated the visible down to zero effectively, so you only have the "exciting" UV from the tungsten lamp, which would be useful.

If you used a camera UV-stop filter over a UV led, you'd get very little of anything.
Short pass UV-only filters look black -
you can see absolutely nothing coming out of this 365nm UV torch through the filters. Skin fluoresces whitish, as does much dust, though:
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Certainly a little one of Bill's "camera" UV filters over the eyepiece would be a benefit if there's dangerous UV around, and little/no harm if not.

The point I was questioning up above, is different: if the UV from a 100W tungsten isn't enough to worry about, then would a 6x (2.6 stops) less powerful UV LED be dangerous? Your eye's iris would open wide, not seeing the UV, but I'd still question whether there's a danger to worry about, at all.

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Re: Olympus CH-2

#26 Post by billbillt » Wed Feb 06, 2019 8:18 pm

My point was that there is a way to effectively filter out "harmful" UV without spending a fortune on a filter from an optics company.. The jury is still out and may stay out on whether UV is such a danger as is feared by some..

BillT

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Re: Olympus CH-2

#27 Post by MichaelG. » Wed Feb 06, 2019 8:20 pm

ChrisR wrote:I wouldn't call 13% attenuation "significant" if I was worried about 365nm UV.
EG-pg15-8a-600w.jpg
O.K. Chris ... I surrender

My initial comment was made in the context of 'lab' vs 'domestic' bulbs.
[i.e. exposed quartz vs filtered by a glass envelope] *

... I am evidently 'out of order' so I will say no more on the matter.

MichaelG.


* Edit: Just had a thought ...
perhaps those 'domestic' bulbs are enveloped with polycarbonate, not glass. I have never examined one.
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Re: Olympus CH-2

#28 Post by TomB » Thu Feb 07, 2019 9:53 pm

Hi
I'm just considering buying a CH-2 but hesitating because of their age. Any thought you can share with me on what to be aware of?
Hope you can help
.
Thanks

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Re: Olympus CH-2

#29 Post by PeteM » Fri Feb 08, 2019 4:29 am

TomB wrote:Hi
I'm just considering buying a CH-2 but hesitating because of their age. . .
In my experience, Olympus microscope mechanisms are relatively bullet-proof -- from the early gray models, through the CH, BH, and BH2. The older ones may have hardened grease that needs removal and replacement, but even 40-50 year old Olympus microscopes will often still operate smoothly.

The lamps and power supplies might be the most frequent problem spots, but as you can see from this thread it's not especially difficult to do a LED or other conversion.

My main concern would be getting decent objectives -- both in quality and condition -- matched with the appropriate eyepieces. The "long barrel" Olympus objectives are preferable -- and there are several different levels including the plain "A" achromats, the very good D Plans, the excellent S Plans, up through the very desirable but expensive S Plan Apos. There are also countless specialized objectives -- sometimes wrongly mixed on the nosepiece of a used microscope.

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Re: Olympus CH-2

#30 Post by Patrick » Fri Feb 08, 2019 12:50 pm

TomB wrote:I'm just considering buying a CH-2 but hesitating because of their age. Any thought you can share with me on what to be aware of?
Hope you can help
I have to say the whole thing was a bit intimidating at the beginning despite the fact that I've been a tinkerer my whole life. Mostly because of the optics. I simply don't have any experience.

Things I made sure to have at hand:
- silicon based grease (it is safe for plastics as it's chemically non-binding)
- optics cleaning fluid [evaporates crazy quick]: 70% vol. diethyl ether (99.5%) + 30% vol. ethanol (96%)
It's easy to get these from eBay.

- Google for:
  • Shipping_the_BH-2.pdf
  • BH2_(BHT-BHTU)_Electronics_rev_4.pdf
  • olympus-bh-2-bhs-repair-manual-lq.pdf
  • CHS_CHT_instructions.pdf
  • olympus-bh-2-brochure.pdf
  • Coaxial_Focus_Repair_Rev_3[BH2].pdf
  • olympus-ch-2-chd-chs-cht-brochure.pdf
  • olympus-ch-repair-manual.pdf
  • olympus-chd-instructions.pdf
  • olympus-chk2-chl2-brochure.pdf
  • olympus-chs-cht-instructions.pdf
  • Olympus_CHD_manual.pdf
These are scans of old literature on the subject.

At least that's the collection I've put together before I started to tear mine apart :) My scope had a ceased mechanism of the focusing leaver stop (it allows you to set the max stage height point for repeatability) and getting into it was a tricky one so I had to be careful with tools (you never know when the screw has a left hand thread till it's to late).

The whole family of these scopes is quite similar in construction so allowing for variations of the model you gonna get - make space for some common sense :D And truly - these are made for education purpose = made like tanks. You have to be lucky or really want to brake one.

I had a blast servicing mine. I encourage everyone who feels up to it. For the shy ones - there are commercial services that will do this for you (probably £100-200... so it's up to you).

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