Re: Enhanced Visual Spectrum.

[Helmut Faugel TE <htf@xxxxxxxxxx>]

On Wed, 16 Jul 1997, Andy Finney wrote:

> Dan wrote:
> 
> Is it possible that something similar can occur with vision whereby the
> wavelengths perceived by a person with exceptional eyesight extend beyond
> visible red into Near Infrared radiation?
> 
> 
> Years ago, my eyesight was thoroughly tested by a PhD optics major at
> Imperial College.  I have slight colour deficiency ... as did a
> surprisingly high proportion of the engineering students.  Well, if I
> remember rightly, when my spectral sensitivity was tested, this guy found
> that I have a slight 'peak' in the near infra-red ... in other words I can
> apparently see a bit of near IR radiation.
> 
> Having said that, I have never actually 'seen' any evidence of this myself.

AFAIK red/green coulor deficiency is very common in europe (up to 7% of
the males in some parts of the czech republic do have this defect, the
rate of females showing this defect is about 100 times less compaired to
males).

But now for something completley different ...

AFAIK Joseph von Fraunhofer which has discovered the absorbtion lines
in the solar spectrum labeled a line at 759 nm as 'A'. At this wavelenght
the sensitivity of the eye is only 1/10 000 as at the peak sensitivity
in the green light and many people do not even see this line then looking
throw a simple spectrograph like Fraunhofer used. Browsing throw the 
institutes library I found an article about the IR-sensitivity of the
human eye published in 1947. The result is that the test persons can
recognice IR-radiation up to 1050 nm but the sensitvity is only the
1/ 30 000 000 000 000 (3x10e-14) part compaired to the peak sensitvity.
The author claims that radiation at 1150 to 1200 nm will be recogniced 
as heat by the skin, before the threshold level of the eye is reached.  
   
> Sadly, my hearing kissed goodbye to 15 KHz a long time ago :=( but both US
> and European TVs (PAL and NTSC) have horizontal frequencies that are very
> very similar and around 15.625 KHz  ... sorry but I can never remember the
> exact numbers.  In fact PAL and NTSC TVs will usually display each others
> pictures although the picture height will be wrong and the image will be
> monochrome.

PAL has 15.625 kHz (625 lines, 25 frames/s), NTSC 15.75 kHz (525 lines, 30
frames/s)

> I'd give the carrots/RADAR story but I see that Clive has already done that.

In a book I read that the eye can detekt 17 photon at a wavelenght of 
505 nm per cellif this photons hit it in less than 1/10s as a very
dim flash. Small amounts of strychnin (poision ! Do not even think
of trying this!) made the eye sensitiver and it was possible to detect
12 photons. Some amateur astronomer swear on this: no alcohol, no
smoke, no observation of the sun and no computer work a few days before
the observation plus eating things which contains much sugar and vitamins. 


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Helmut FAUGEL                       |  Tel.   : +49 / 089 / 3299 2245
Max-Planck-Institut f. Plasmaphysik |  Fax    : +49 / 089 / 3299 2558
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D-85748 Garching bei Muenchen       |
Germany                             |
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