Re: My eye sensitivity to blue-violet higher than normal


greenboxmaven
 

A very interesting discussion of human vision.  As far as films and phosphors, in the early 1950s, television programs were recorded for later replay by taking a motion picture of a CRT. The phosphor was  blue and UV with very short persistance, and the film was designed to perform best with it. A more modern and fairly easily obtainable similar CRT was used in the B&K "Television Anaylist" from the 1960s, which contained a flying spot scanner. The old test pattern, dot, bar, and crosshatch slides were provided for adjusting the convergence on old color TVs, for those who remember how. B&W photgraphic slides could also be used for images, and many TV shops used them for advertising on sets for sale.

    Bruce Gentry, KA2IVY

On 5/23/21 20:28, Harvey White wrote:

I can tell you what I've heard, without any particular authority, although my wife does have blue eyes, if that helps.

1) during WWII, the navy used ultraviolet lights (long wave) to illuminate phosphors on the decks of carriers.  Some few could see the lights, they invariably had blue eyes.  Apparently, people with blue eyes don't have a pigment that can block UV.

(ELK can see in the UV spectrum.  Wolves on snow blend in under normal light, when looked at under UV light, the wolves stand out.)

2) there is sufficient chromatic abberation in the human eye that blue and red focus at different distances.  Find a red/blue LED display, and you'll see that the blue seems to be more distant. Human vision is optimized for forest light, a rather yellowish green.

3) judging from the phosphors in the normal light fluorescent lamps, I'd guess that the different phosphors (more blue part, look and it seems to be yellow and blue) have different persistence, with blue being shorter than yellow.

Some things to think about:

1)  you're probably more sensitive to nighttime glare, the ones from the hopped up trucks with the low beams (if not high) that are almost blue in color.  A suggestion is to wear yellow tinted glasses.

2) as you get older, perhaps with cataracts, blue light scatters more, and will increase your sensitivity to glare.

3) it's easier to deal with blue sensitive photo film.  There's more energy in blue light, and the film can be handled under red light (dim, mind you).  Photographic paper is primarily blue sensitive if it's B&W.  (Orthochromatic).  There are orthochromatic (blue sensitive) and panchromatic films. Panchromatic films need to be handled under total darkness or the dimmest green (light sensitivity of the human eye) filter available.  Orthochromatic (Kodak fine grain positive release film, or kodalith, for instance) are safe under dim red light.

4) P11 phosphors were designed to match blue sensitive film, have a *very* short persistence for recording high speed events, and when viewed, will flicker a lot more.

Note that the normal phosphors are really in the yellow/green spectrum, with various persistences, so that they can be viewed under dim light.  The orange phosphors in some radar tubes (P12), were designed for command deck use under night conditions, where all the lighting was red.

Humans have a chemical called rhodopisin, (sp?) which increases the sensitivity of the rods (monochrome sensors) in the eye.  The center point of the eye has a lot of cones (color sensors) and not so much rods.  As you go out from the center of vision, you start to run out of cones, and get more rods.

In terms of vision, you look at what's in your central vision and you get high resolution color.  It's not a large high resolution area at all.  As you start with peripheral vision (rods) you get light sensitivity, sensitivity to movement, but no color. Translation:  SOMETHING IS TRYING TO SNEAK UP ON YOU, LOOK OVER HERE!!!

Since cones aren't very sensitive to light, they don't do well in the dark.  Rhodopsin is a chemical that takes a bit of time, but increases the sensitivity of the rods to light.  This is your "night vision".  Rhodopsin is ionized (read: destroyed) by blue light.  Blue light = no night vision, which is why astronomers use red light at night, and why ship's bridges are in red light when under night conditions.

Yet another reason why blue phosphors (P11) aren't used for low light level situations.  The P7 phosphor uses a blue layer behind a yellow layer.  The blue layer ultraviolet causes the yellow layer to glow with a long persistence.  Normally, for night time and radar, these are used with orange or yellow filters.

That's the history as I know it.

Harvey



On 5/23/2021 7:34 PM, Mark Vincent wrote:
I would like to know from anyone in this group that has a good educated to
known medical reason why I have a higher sensitivity and ease of viewing
light that is blue to violet so easily. I understand the rods and cones in
the eye and have enough medical knowledge to understand the Latin and Greek
terms of medical words. I have NO problem in seeing, focusing or any form
of eye strain on light that is in the high frequency part of the spectrum
of blue to violet, including indigo. I have always been this way. One note,
I do have blue eyes if that makes any difference. They are not the striking
steel blue that can look like blue lasers. Jean Harlow had steel blue eyes,
as an example of someone. Blue/ steel blue eyes in a male is far more
common in a male than a female.

Another thing I have with my eyes is that under 50/60 c/s flicker, I will
get a severe migraine and have the vision of "Mr. Magoo" within a few
minutes that takes a few hours to wear off after being removed from the
flickering light(s). For reading and general lighting, I prefer carbon
filament (Ferrowatt). Tungsten is fine.

Brenda mentioned having a RM565 scope with a blue trace (must be P11 by the
model)  that she gets eye strain easily. This is what finally made me ask
the group this. Others have mentioned how P11, blue, is nice briefly, not
for any time without the owner having eye strain and hard to focus on. I
have seen older posts on this group and other places online about people
saying blue trace is nice but annoyed by the hard to focus on and eye
strain within a few minutes. I have a couple of friends with blue eyes that
I asked about blue-violet phosphour. They said it is nice to glance at or
for a short time, not for any longer. They said they would prefer P1, P31,
etc, that is in the green area to look at for any length of time, a minute
or more. I will deal with P1 or P31. I find P2 the WORST to look at. The
blue part is fine, the cyan afterglow I find bilious. P7 is not as bad as
the afterglow is yellow with only the blue seen with a proper filter. Even
so, I will keep the intensity of a P7 low so as to only see the blue.

I know storage types need a P31 because of the secondary emission.
Something like the 2467/B or 7104 with the MCP could have been made with
other phosphours when made. The MCP does not care about the phosphour, only
acting like a photomultiplier.

I would like to find the P11 crts for my 556, 7603 and 465. The P31s in
them are in very good condition. I prefer the P11 because of the thinner
trace, ease on my eyes. and faster decay time. To find a 502A with P11 and
T317P11 for my 317 would be great. I know the 502A is 2mc capacity. The
7000 series I have, except for the 7934 and 7104, now have the P11 in them.
I do have good P31 types I removed from the scopes sitting around. I do
have a few of the 300, 400 and 500 series with the P11. If I can find
someone who can successfully rewind the high voltage transformers for the
older types, I would really like P11 for me 545B and 547 after getting
these transformers rewound. The only thing I have seen P16 in is a B&K 1076
analyst. That colour does not bother me at all. So far I have not seen a P5
although having any of these, 3AP5 for example, in place of a P1 would be
great. I know the decay time and light output of P5 is less and P11.

For any plant that has flowers, I do not mind any colour.

Mark







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