April 9, 2012
to be posted on silentnursery.com and nobabies.net
Brad Amos
MRC Laboratory of Molecular Biology
Hills Road
Cambridge DB2 2QH
UK
01333 411640
fax o1223 213556
ba@mrc-lmb.cam.ac.uk
Dear Dr. Amos:
I was interested by the recent write up about your revolutionary microscope. (Angela Saini New Lens Offers Scientist a Brighter Outlook SCIENCE vol. 335 no. 6076 March 30, 2012 page 1562) It takes me back forty years when I used to toy with optics. What I did then was design and patent a microscope/telescope system that was low tech but seemed at the time to be an improvement over what was then available for general use. The patents are long since expired, but I thought you might be interested in what I had done. Maybe there is a use for the idea somewhere.
A classical compound microscope or a Kepler telescope consists of an objective lens that throws a real image that is then inspected with an eyepiece. My interest was in just how the real image is inspected.
The usual eyepiece is a strong lens. This requires some engineering, introduces a significant amount of light loss and has limited ability to correct for refractive errors of the cornea. What I did was to put on swimming goggles and flood one eye with water. I could then cast the real image on my retina without focusing it again. Corneal errors were by and large eliminated because the cornea did no focusing.
I learned a few things. For one thing, I found that the fresh lens of a cow eye had amazingly little tendency to break light into colors. I tried putting a beam of white light through a cow lens I had broken, and sure enough it sent out specks of light the way a diamond will in sunlight. But while the diamond puts out little rainbows, all of these spots were pure white.
This actually corrects for some chromatic aberration. Light passing the cornea is refracted, introducing the chromatic aberration of water, which is pretty pronounced. Then it reaches the lens, which is between aqueous humor and vitreous humor, but which we will just think of as water. Imagine the lens replaced by air. There is now a strong water-air lens which is negative. It corrects for chromatic aberration but at the cost of eliminating the real image (or throwing it very far back). Now re-introduce the lens in air with its ability to focus without chromatic aberration. A clean image is now presented to the retina. Reduce the amount of air until it is gone and you have the functional actual eye.
The correction is not perfect, at least not in a cow. When I took an eye and cut it in half across the equator perpendicular to the path from center pupil to retina and mounted it on a microscope slide, I could still get it to cast a real image on a screen behind it, and it still had chromatic aberration, although to my inspection only about half what the cornea introduced.
I found the best shape for the front of the goggle was flat, but I am sure the correction of the refractive errors, although excellent for spherical and astigmatic aberration, still has a degree of chromatic aberration. I was unable technically to demonstrate this. (I was working on the kitchen counter, for goodness sake.) But with a little ray tracing and adding a judicious amount of curvature to the front of the goggle, that should be easily corrected. Voila. Your retina for the first time in its life actually gets to interpret an optically clean image.
I had some fun with it. Using a lens for a 35 mm SLR camera in those pre-digital days, and using the flooded goggle I could see with a clarity and color saturation that revealed details around me I had not been aware of at any distance with my natural eyes.
All right. Maybe I was carried away with my own cleverness. But although others have found the device works, nobody else has actually taken an interest is just how well it works. The patent office rejected my initial claim saying the device was impossible, so I had to send my lawyer to Washington with a microscope to show it in action. They relented. I thought any improvement in a microscope, particularly one that was dirt cheap and broke new ground, would attract attention. You know as well as I that ideas can be ignored as well as purloined.
If somebody actually works out the ideal curve of the front face of the goggle, of course, that would be patentable, I should think.
Tap water on the cornea is irritating. The corneal epithelium has to live, meaning getting oxygen and nutrition. Oxygen is obviously easy; it’s right there. If you remember crying as a child, you remember that tears are sweet. So the cells of the corneal epithelium live their brief lives on a diet of sugar water. I found that a dilute sugar water solution was much less disagreeable than fresh water or salt water. Don’t even think about trying eye drops. And anesthetizing the cornea would be the act of a madman so deranged he would make even me seem normal.
Safety, of course, is a serious consideration. All I can say is that, except for the eye drops, it was never any worse than swimming underwater without goggles and with my eyes open. But maybe I was just lucky.
For real use, of course, you could imagine a goggle chamber that was dry most of the time, but which could be quickly flooded and drained when detail was needed. It would be sort of like an oil immersion lens. You spend ninety percent of the time looking around under lower power and then go under oil for a brief look.
Alas for those happy days. My current interest, as you can tell from my web sites, is in fertility. Although I have been I think successful in establishing that normal fertility requires (surprisingly, although it should not be a surprise) marrying kin, say third of fourth cousins, I find that the idea is getting the cold shoulder from just about every direction. Odd. I would have thought that everybody knew babies were important.
Meanwhile I wish you all the best. If you have any interest in this flooded cornea technique, feel free to make it your own. I gave up the pursuit years ago, although I would be most pleased if it did somebody good somewhere.
Sincerely,
M. Linton Herbert MD
There have been 50,162 visitors so far.