New project: LED conversion for LOMO Biolam

[75RR]

Was a little worried by the low end of the graph but after your comment I looked at it again and realized that no part of it was below 400nm, and at 20% Relative Radiant Power it was up to 430nm. So I feel a little better.

In the same dimmed room, I aimed my microscope LED at the same shirt, no reaction.

That was positive. :)

The next step should have been using the salvaged UV filters to see if they blocked the UV emissions from the cheap flashlight, but I didn't think of that at the time.

That would have been very interesting. Hope you find the time to conduct the test.

[gekko]

Ingenious tests. The UV camera filters that I got and mentioned above that claim to absorb all UV light are Tiffen Haze 2A (check the Tiffen wbesite).

[Crater Eddie]

Hmmm... I might be mistaken about those salvaged filters being UV filters. They don't make any difference at all in the cheap flashlight making the tee-shirt fluoresce.
They are, however, very good IR filters.
As you might know, most modern tv remote controls work by sending a signal via coded IR pulses transmitted by IR LEDs mounted on the front end. Place an IR filter in front of the remote and it can no longer communicate with the intended device. You might not know that many digital cameras make very good IR detectors, which makes a great demonstration of the effectiveness of the IR filters.
Check out the linked YouTube video I made: (you might want to turn the sound down, sorry about that)

https://www.youtube.com/watch?v=w3j0p9V ... e=youtu.be

So I guess if we want to make certain that no UV is transmitted through the eyepieces we should invest in a real UV filter as Gekko suggested.
CE

[gekko]

Crater Eddie, I like your practical and effective experimental approach! I found it very difficult to negotiate the Tiffen website, but I finally found the Haze 2A filter:
http://www.tiffen.com/displayproduct.ht ... um=49HZE2A
(The price at B&H/Adorama/Amazon is less than half this, depending on the size).

[75RR]

They don't make any difference at all in the cheap flashlight making the tee-shirt fluoresce.

Pity your filters were not UV. Good that you checked though.

Found these filters while looking up some Kenko filters that were for sale on a local ebay equivalent.
Unfortunately those for sale were not these particular ones.
Out of all the UV filters on their site only these two showed a UV stoppage graph.

http://www.kenkoglobal.com/photo/filter ... _WIDE.html

http://www.kenkoglobal.com/photo/filter ... MC_UV.html

[Crater Eddie]

Thanks Gekko and 75RR for the links, I'll check them out.
After pouring over the LED specs I'm not as concerned as I was about possible UV emissions, but it certainly doesn't hurt to be on the safe side.
I am a firm believer in experimentation and demonstration. You can read spec sheets all day, but there's nothing like a good visual to drive the points home, and sometimes you turn up unexpected and interesting results.
CE

[75RR]

Was having another look through the Cree pdf leaflet when I noticed a link within to what it refers to as: LED Eye Safety application note.
On my Cree XLM leaflet it is on page 10. On the XTE leaflet it is on page 15.

Mine is a XML-U2 Cool white
Crater Eddie's is a CREE XT-E neutral white LED
Worth a look.

This is a link to their products page – clicking on each image takes one to the individual product page where one can download the data sheet.
http://www.cree.com/LED-Components-and- ... ucts/XLamp

[Crater Eddie]

Thanks for posting the link, that's great information. I had read that of course.
I consider the "moderate risk" at maximum drive as acceptable, as for visual use I run the LED at much less than maximum drive. The only time I have to turn it up is for recording video, and I'm not looking through the eyepiece during that time.
Considering that I usually run at around half to two thirds drive (just a rough guess), and have lots of glass in the light train, I think it's good.
I am interested in why you chose the "cool white" LED over the "neutral white".
CE

[75RR]

I am interested in why you chose the "cool white" LED over the "neutral white".

It is the one Ichthyophthirius recomended on photomacrography.net (or the one he is using anyway).
http://www.photomacrography.net/forum/v ... c&start=30

[Crater Eddie]

Oh, I see. I tend to forget that you are more photography oriented. Thanks for linking to that thread, I'll read through it as it looks very interesting.
CE

[Crater Eddie]

Over the weekend, I did compare the filament of the original halogen bulb to the size of the LED, and the LED is indeed noticeably smaller in diameter than the length of the bulb filament. Of course the LED is considerably larger in diameter than the width of the bulb filament, so does this even out in the long run? I'm not sure. I do not have Koehler illumination anyway, so I don't think it is a critical matter. But still, it makes me want a larger diameter LED, "just because".

[75RR]

But still, it makes me want a larger diameter LED, "just because".

This link to the Cree products page offers a quick way to compare LED sizes.
http://www.cree.com/LED-Components-and- ... ucts/XLamp

[Crater Eddie]

That's a pretty handy page, thanks for the link.

[75RR]

My module arrived today from China.
Looks like they sent two!
Do I just snap them apart? Carefully?

[Crater Eddie]

Bonus! Yes, just carefully snap them apart. The pc board is scored or perforated, so it should break evenly.
CE

[Crater Eddie]

Following on the success of this project, I am now having thoughts on building an LED conversion for the bigger scope.
The old scope used a 20 watt halogen bulb, the new scope uses a 100 watt halogen bulb, and I often find myself running it at full brightness when using higher magnification with the trinoc in photo mode, so this might be a bit more of a challenge. I'll have to switch to a higher power LED, and it might well take a different controller to run it.
Parts are ordered, stay tuned.

Later...

Hmmm... I see a lot of 3 watt LED retrofit modules offered for sale for replacing 100 watt halogen bulbs. Maybe I should try adapting my current setup to the new scope first.
<mental gears turning again>

[gekko]

I'm surprised that you run the 100 W halogen lamp at maximum voltage. I've never felt the need to apply more than 80% rated voltage to my 50-W bulb. Is it because you keep the camera's ISO low to reduce noise? I used to use my Labophot for phase contrast and it used a 20 watt halogen bulb.

[Crater Eddie]

It's for the camera, yes. It doesn't have ISO settings per se, since it's basically a hyped up web cam, but that's close enough. It needs a LOT of light.
Visually I don't have to have it up nearly that high, but with the 40x objective, and especially with the LOMOVAR cranked up, I need the extra light to keep the camera from getting too slow and choppy. If the promised rain moves in this Sunday I'll have time to try out my current LED system and see how it works.
CE

[zhuhaiping]

I would be interested to see

[Crater Eddie]

I would be interested to see

What is it that you would like to see? This is an old conversation, but I would be glad to show whatever it is that you are interested in.
CE

[Kpm9c9VNwu]

Hello. Sorry for commenting here but I can't send private messages yet.
Does anyone know how to reverse the stage like in the picture on the first page, microgreen's post? I have the same and it is the opposite, and I can't reverse it because the control interferes with the bracket in which the stage is mounted and the holes are not in the same place. Do you need some kind of adapter or completely different stage?
Mine is like this:

[75RR]

Have not seen microgreen for a while now.

Perhaps Crater Eddie can help. You might want to post on his thread below.

viewtopic.php?f=24&t=104&view=next

[Kpm9c9VNwu]

Thanks, I will.