The new LED device has arrived and been installed. LEDs are Royal Blue, Blue, Green and White. I'm going to be ordering some UV LEDs in the same mount and will try them in a week or two.

But I did a quick test. The LED is perfectly centred and I just put the holder in and tightened the screw. A little adjustment of the mirror; and then the structure of the LED surface was focussed on the diaphragm of the Lomo Aplanatic 1.4

I put the Lomo 90/1.30 in and found a strew of KK A pellucida I made a couple of months ago. I used a convex knife edge in the filter holder and saw lines on the first valve I found. The picture is the last (9) in the Don Williams Photo Album. The lines are beaded and zooming up in Photoshop almost shows dots.

The LED was the Luxeon Star Royal Blue running at 700ma powered by a TekPower HY1503C power supply.
[ Luxeon V Star datasheet (Royal Blue, Blue, Green), 5W max. rating ]
[ Luxeon Star datasheet (White, warm White) ]

No filters anywhere. Magnification 2925X. Immersion oil was Olympus 1.5155.

I'll post pictures of all the parts as soon as I have time to take them.

Don W

Pictures of the LED modification are here:
  Link : http://picasaweb.google.com/don.donwilliams/...
and following -- in the middle of another gallery because I was in a hurry and didn't change the numbers.

I have a thermocouple on the front of the mount to measure the LED temperature and will conduct experiments to see how they behave when run at 10% over their rated current. There is a fan under the housing (for the Halogen lamp) but I don't think the LED will ever need this.

This device was made for me by an old friend, George Fellingham in San Jose, who was an intern at my Institute in SA. He's a consultant Electrical Engineer and specializes in analog and digital (control) electronics. All the important changes made here have been done with parts made by him -- from drawings and designs (and strange ideas) sent from Finland.

I'm going to set up another Picassa gallery solely for scientific stuff soon and members won't be subjected to all kinds of other irrelevant pictures after that.

Don W

I needed to satisfy myself that the LED could do as well as the Flaming Halogen 100W. So I messed around bit until I could see dots and I've posted two pictures:
 Link : http://www.science-info.net/pages/EDFWilliams/LED/181948.jpg
 Link : http://www.science-info.net/pages/EDFWilliams/LED/182036.jpg
[ Logitech 4000 webcam, 1280x960 ]

They are not wonderful but all the way down on the left hand side of the Raphe there are dots to be seen. There is not enough light for such oblique illumination but this is also the case with the powerful Halogen.

Everything is the same as before: Wonderful Lomo Apo 90/1.30; Aplanatic Condenser 1.4 immersed; convex knife edge in filter holder; LED Royal Blue Luxeon Star at 700ma; no filters. Final magnification just under 3000X.

I'm satisfied with the design and operation. Now I'll try some of the other LEDs.

Don W

Hi Don,
You might like to have a look at Terry's work with LEDs:
  http://www.microscopy-uk.org.uk/mag/imgjun03/Pellucida1.jpg

Kind Regards, Charla Mason, Victoria Canada

The Micscape A.pellucida image:
 Link : ../LongLinks/LL_06.1.htm

and the June 2003 article by Terry Gunby, 'Notes on resolving some diatoms with Blue LED oblique lighting':
 Link : ../LongLinks/LL_06.2.htm

Later, Keith

"Don Williams" wrote:
> These links are an awful mess.

Baumueller,  'MBC-10 Light converted to LED' (May.2006)

Pavlis,  'Star LEDS for two microscopes' (Mar.2006)

I managed to image dots using a White Luxeon Star LED and a 'Royal Blue' filter -- Leitz -- but number unknown. However I had to use 600 video frames, stack them in Registax, make a flat field noise stack and use Giotto to correct the picture. The amount of work involved is not worth the awful looking result. On top of this I don't understand how Giotto works and can't use it properly anyway. It doesn't much help that the German menus are not intuitive.

Don W

Hi Don,
On searching for a Luxeon datasheet you soon get to find out that there is a wide range of these devices available!
Do you happen to have the exact part number available for each of the devices you are using?

For the Luxeon white LEDs there seem to be two versions with very different spectral characteristics.

Your design to allow interchanging the LEDs, and maintaining an accurate optical alignment, is slick.
But from the photos it's not obvious as to how the electrical connections are implemented. It looks as if your devices have a pin assembly, rather than the standard solder pad.

Thanks, Keith

"Don Williams" wrote:
> I managed to image dots using a White Luxeon Star LED...

The pins are soldered on to the Star Mount pads.

The LED part numbers are LXHL-PW03 and LXHL-PR02.

Each is protected by a 1 Watt 1N4007 diode in reverse parallel, in case of operator error. The original design had screw-on ends, but George decided to drop that idea in favour of a plug and socket for each LED. It's fiddly to change them with this design -- but much simpler. I don't have the green, cyan and blue LEDs yet. The UV's are also coming later. The 1W diode is probably not necessary, but was put on 'Just In Case.'

I'm going to turn my attention to the white LED's use for video work next. By the way the lines on AP are perfectly visible using the white LED and no filters anywhere. But the dots need a lot of messing about, as I said, and it's not worth the effort since the Royal Blue does the job. And UV ought to do better.

Don W

Don,
I think the image is an interesting example of structure that can be discerned after sheer persistence. We need to bear in mind a distinction between being able to detect structure, and draw inferences from it, and the separate, but laudable, desire for aesthetically pleasing images. Your image serves the former purpose admirably.

Selwyn

Oh yes. I've struggled for decades with images (thousands upon thousands of electron micrographs) that often looked awful, but told volumes.

Don W