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M

Martin Brown

Guest
On 04/08/2020 11:07, jrwalliker@gmail.com wrote:
On Tuesday, 4 August 2020 06:46:46 UTC+1, Jan Panteltje wrote:

Indeed, wonder how far into the UV a normal prism of an old pair
of binoculars will go,
by rotating it you can make a nice spectrometer.

Would the prism in binoculars be made from dispersive glass?
Yes. The way that the prisms are used for near perpendicular entry and
exit of the light rays and a total internal reflection there is very
little dispersive effect at all. UV doesn\'t go through glass very well.

The lenses of binoculars need to be achromatic doublets. There is no
such thing as non-dispersive glass. Only clear glasses with different
dispersions such that a well chosen pair can make a workable achromat
(matched focus for two wavelenghts) or apochromat (three).

One of the exotic solutions to the problem uses single crystal calcium
fluorite as an optical element which is brittle as hell to work with.

The OP might stand a chance with the photoelectric effect from a cerium
metal \"flint\" sold for outdoorsmen to strike energetic sparks onto
tinder. That has a metallic workfunction of about 3eV which is ~UV
photon range. Might be worth a look in the SciAm Amateur Scientist
archives in case it has been done before.

I think the same sort of flint material is used in some cheap disposable
lighters but I have never tested it. Most rare earth metals are in the
same ballpark for WF so any of them ought to work.

--
Regards,
Martin Brown
 
P

Phil Hobbs

Guest
On 2020-08-04 06:53, Martin Brown wrote:
On 04/08/2020 11:07, jrwalliker@gmail.com wrote:
On Tuesday, 4 August 2020 06:46:46 UTC+1, Jan Panteltje  wrote:

Indeed, wonder how far into the UV a normal prism of an old pair
of binoculars will go,
by rotating it you can make a nice spectrometer.

Would the prism in binoculars be made from dispersive glass?

Yes. The way that the prisms are used for near perpendicular entry and
exit of the light rays and a total internal reflection there is very
little dispersive effect at all. UV doesn\'t go through glass very well.
Or through optical cement.

The lenses of binoculars need to be achromatic doublets. There is no
such thing as non-dispersive glass. Only clear glasses with different
dispersions such that a well chosen pair can make a workable achromat
(matched focus for two wavelenghts) or apochromat (three).

One of the exotic solutions to the problem uses single crystal calcium
fluorite as an optical element which is brittle as hell to work with.

The OP might stand a chance with the photoelectric effect from a cerium
metal \"flint\" sold for outdoorsmen to strike energetic sparks onto
tinder. That has a metallic workfunction of about 3eV which is ~UV
photon range. Might be worth a look in the SciAm Amateur Scientist
archives in case it has been done before.

I think the same sort of flint material is used in some cheap disposable
lighters but I have never tested it. Most rare earth metals are in the
same ballpark for WF so any of them ought to work.
Flints are usually mischmetal IIUC. Interesting idea though--might
work if he can get the surface clean enough.

One possibly useful fact: free electrons are stable in nitrogen gas, so
you can collect them easily with a grid.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
P

Phil Hobbs

Guest
On 2020-08-03 12:35, Pimpom wrote:
On 8/3/2020 7:09 PM, George Herold wrote:
On Monday, August 3, 2020 at 3:36:39 AM UTC-4, Pimpom wrote:
I\'d like to be able to determine the intensity of UV radiation
from different sources like CCFLs, the sun under various
conditions, UV torchlight, etc. The sensor doesn\'t have to be
very linear, only approximately so. It\'s not necessary to measure
the absolute intensity either - knowing the relative values is
enough.

Will a UV LED work? I don\'t have any with me, so I can\'t just try
it out.
Hi pimpon, IDK.  You somehow have to select what wavelength \'band\'
you want to see.  This could be with some UV filters, or spectrometer
and a broad band detector (photodiode) or pick a detector with some
wavelength response that you can use.

I think of Forest Mimms for led\'s as detecotrs...
http://www.forrestmims.org/scientificresearch.html
here\'s an article about measuring the ozone layer.
http://www.forrestmims.org/images/SCIENCE_PROBE_TOPS_PROJECT_NOV_1992_small.pdf


George H.


You and others have brought up the question of which UV band I\'m
interested in. I have no specific application in mind at the moment. I
just wanted to have a general idea of how UV levels differ between
sources and, in the case of the sun, with the weather and its position
in the sky.

If I had to choose filter and sensor types for wavelength, I\'d start
with near UV in the mid-300s nm.

My problem, as usual, is that there\'s little chance of getting the
filter materials mentioned by people on the internet, especially with
the pandemic disrupting everything. To make things worse, with the
tension between India and China, I don\'t know if I\'ll still be able to
order from AliExpress.
There are flame sensor tubes, and the poor man\'s version is an NE-2 neon
bulb. I\'ve seen that published someplace but can\'t lay my hands on it
at the moment.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
S

server

Guest
On Tue, 4 Aug 2020 10:49:15 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-03 12:35, Pimpom wrote:
On 8/3/2020 7:09 PM, George Herold wrote:
On Monday, August 3, 2020 at 3:36:39 AM UTC-4, Pimpom wrote:
I\'d like to be able to determine the intensity of UV radiation
from different sources like CCFLs, the sun under various
conditions, UV torchlight, etc. The sensor doesn\'t have to be
very linear, only approximately so. It\'s not necessary to measure
the absolute intensity either - knowing the relative values is
enough.

Will a UV LED work? I don\'t have any with me, so I can\'t just try
it out.
Hi pimpon, IDK.  You somehow have to select what wavelength \'band\'
you want to see.  This could be with some UV filters, or spectrometer
and a broad band detector (photodiode) or pick a detector with some
wavelength response that you can use.

I think of Forest Mimms for led\'s as detecotrs...
http://www.forrestmims.org/scientificresearch.html
here\'s an article about measuring the ozone layer.
http://www.forrestmims.org/images/SCIENCE_PROBE_TOPS_PROJECT_NOV_1992_small.pdf


George H.


You and others have brought up the question of which UV band I\'m
interested in. I have no specific application in mind at the moment. I
just wanted to have a general idea of how UV levels differ between
sources and, in the case of the sun, with the weather and its position
in the sky.

If I had to choose filter and sensor types for wavelength, I\'d start
with near UV in the mid-300s nm.

My problem, as usual, is that there\'s little chance of getting the
filter materials mentioned by people on the internet, especially with
the pandemic disrupting everything. To make things worse, with the
tension between India and China, I don\'t know if I\'ll still be able to
order from AliExpress.

There are flame sensor tubes, and the poor man\'s version is an NE-2 neon
bulb. I\'ve seen that published someplace but can\'t lay my hands on it
at the moment.

Cheers

Phil Hobbs
I designed some flame detectors, to check for flame-out on steamship
boilers. A flame-out can have serious consequences if you don\'t shut
off the fuel pump pretty soon.

The sensor was a golf-ball sized quartz tube. It ran at basically line
voltage. It was blind to full sunlight but would fire from a match
held a couple of feet away.

Might have been Hamamatsu.

The ships are mostly diesel now. Steam plants are efficient but too
complex.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
P

Phil Hobbs

Guest
On 2020-08-04 11:07, jlarkin@highlandsniptechnology.com wrote:
On Tue, 4 Aug 2020 10:49:15 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-03 12:35, Pimpom wrote:
On 8/3/2020 7:09 PM, George Herold wrote:
On Monday, August 3, 2020 at 3:36:39 AM UTC-4, Pimpom wrote:
I\'d like to be able to determine the intensity of UV radiation
from different sources like CCFLs, the sun under various
conditions, UV torchlight, etc. The sensor doesn\'t have to be
very linear, only approximately so. It\'s not necessary to measure
the absolute intensity either - knowing the relative values is
enough.

Will a UV LED work? I don\'t have any with me, so I can\'t just try
it out.
Hi pimpon, IDK.  You somehow have to select what wavelength \'band\'
you want to see.  This could be with some UV filters, or spectrometer
and a broad band detector (photodiode) or pick a detector with some
wavelength response that you can use.

I think of Forest Mimms for led\'s as detecotrs...
http://www.forrestmims.org/scientificresearch.html
here\'s an article about measuring the ozone layer.
http://www.forrestmims.org/images/SCIENCE_PROBE_TOPS_PROJECT_NOV_1992_small.pdf


George H.


You and others have brought up the question of which UV band I\'m
interested in. I have no specific application in mind at the moment. I
just wanted to have a general idea of how UV levels differ between
sources and, in the case of the sun, with the weather and its position
in the sky.

If I had to choose filter and sensor types for wavelength, I\'d start
with near UV in the mid-300s nm.

My problem, as usual, is that there\'s little chance of getting the
filter materials mentioned by people on the internet, especially with
the pandemic disrupting everything. To make things worse, with the
tension between India and China, I don\'t know if I\'ll still be able to
order from AliExpress.

There are flame sensor tubes, and the poor man\'s version is an NE-2 neon
bulb. I\'ve seen that published someplace but can\'t lay my hands on it
at the moment.

Cheers

Phil Hobbs

I designed some flame detectors, to check for flame-out on steamship
boilers. A flame-out can have serious consequences if you don\'t shut
off the fuel pump pretty soon.

The sensor was a golf-ball sized quartz tube. It ran at basically line
voltage. It was blind to full sunlight but would fire from a match
held a couple of feet away.

Might have been Hamamatsu.

The ships are mostly diesel now. Steam plants are efficient but too
complex.
Hamamatsu still makes them.

Boilers also have that nasty hydrogen-embrittlement problem when run too
hot, and of course the standard of maintenance in your average merchant
ship is not exactly medical grade.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
S

server

Guest
On Tue, 4 Aug 2020 11:20:17 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-04 11:07, jlarkin@highlandsniptechnology.com wrote:
On Tue, 4 Aug 2020 10:49:15 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-03 12:35, Pimpom wrote:
On 8/3/2020 7:09 PM, George Herold wrote:
On Monday, August 3, 2020 at 3:36:39 AM UTC-4, Pimpom wrote:
I\'d like to be able to determine the intensity of UV radiation
from different sources like CCFLs, the sun under various
conditions, UV torchlight, etc. The sensor doesn\'t have to be
very linear, only approximately so. It\'s not necessary to measure
the absolute intensity either - knowing the relative values is
enough.

Will a UV LED work? I don\'t have any with me, so I can\'t just try
it out.
Hi pimpon, IDK.  You somehow have to select what wavelength \'band\'
you want to see.  This could be with some UV filters, or spectrometer
and a broad band detector (photodiode) or pick a detector with some
wavelength response that you can use.

I think of Forest Mimms for led\'s as detecotrs...
http://www.forrestmims.org/scientificresearch.html
here\'s an article about measuring the ozone layer.
http://www.forrestmims.org/images/SCIENCE_PROBE_TOPS_PROJECT_NOV_1992_small.pdf


George H.


You and others have brought up the question of which UV band I\'m
interested in. I have no specific application in mind at the moment. I
just wanted to have a general idea of how UV levels differ between
sources and, in the case of the sun, with the weather and its position
in the sky.

If I had to choose filter and sensor types for wavelength, I\'d start
with near UV in the mid-300s nm.

My problem, as usual, is that there\'s little chance of getting the
filter materials mentioned by people on the internet, especially with
the pandemic disrupting everything. To make things worse, with the
tension between India and China, I don\'t know if I\'ll still be able to
order from AliExpress.

There are flame sensor tubes, and the poor man\'s version is an NE-2 neon
bulb. I\'ve seen that published someplace but can\'t lay my hands on it
at the moment.

Cheers

Phil Hobbs

I designed some flame detectors, to check for flame-out on steamship
boilers. A flame-out can have serious consequences if you don\'t shut
off the fuel pump pretty soon.

The sensor was a golf-ball sized quartz tube. It ran at basically line
voltage. It was blind to full sunlight but would fire from a match
held a couple of feet away.

Might have been Hamamatsu.

The ships are mostly diesel now. Steam plants are efficient but too
complex.

Hamamatsu still makes them.

Boilers also have that nasty hydrogen-embrittlement problem when run too
hot, and of course the standard of maintenance in your average merchant
ship is not exactly medical grade.

Cheers

Phil Hobbs
1200 psi steam is nasty, corrosive stuff. It would dissolve stainless
steel, especially at pipe bends. Each engine room had a small
chemistry lab to check the feedwater quality often.

The pipe joints were all welded. A weld could have a tiny pinhole
defect. The way to find a leak was to wave a broomstick all around all
the welded joints. A silent, invisible leak would cut the end off like
a laser. It could cut your head off, too.

Maintenance issues killed steam in favor of diesel. The steam systems
were just too complex.

A critical component of a steamship was the small independent
take-home motor.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
A

amdx

Guest
On 8/3/2020 2:36 AM, Pimpom wrote:
I\'d like to be able to determine the intensity of UV radiation from
different sources like CCFLs, the sun under various conditions, UV
torchlight, etc. The sensor doesn\'t have to be very linear, only
approximately so. It\'s not necessary to measure the absolute intensity
either - knowing the relative values is enough.

Will a UV LED work? I don\'t have any with me, so I can\'t just try it out.
Here are a couple of cheap UV pass filters.

> https://www.mpja.com/UV-Lights/products/141/

Near the last items on the page.

Don\'t no if you could get them or if they will help you.

                                         Mikek


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