Video mode: sensor vulnerable to lasers

On Fri, 13 Aug 2010 00:10:57 -0700, charles
wrote:

On Tue, 10 Aug 2010 14:05:47 -0700 (PDT), RichA
wrote:

On Aug 9, 8:08*pm, R Davis wrote:
On Mon, 9 Aug 2010 13:51:58 -0700 (PDT), RichA
wrote:

On Aug 9, 4:07*pm, Me wrote:
Alan Browne wrote:
Be careful when using video mode (or long exposures) when lasers are
around.

http://vimeo.com/13450755

Even worse:

http://www.reuters.com/article/idUSL...080714?sp=true

Brainless to fire a Argon laser into a crowd instead of over their
heads. *Even those little frequency-shifted green pocket lasers can do
damage, let alone an industrial entertainment laser.

Especially when they are pot-modded to ~100mw. I had a couple visitors here
yesterday, their son wanted to play with my 405nm and green laser pointers
that I have. ($7.95 w/ free shipping from China on E-Bait, but their
potentiometers are adjusted to 5mw to get them through customs.) I
especially like the green pot-modded ones. The beam (not just terminal dot)
is brightly visible in the air in full sunlight. He was having fun lighting
matches with them. I warned him to not stare at the focused beam on the
paper-matches too intently. He was seeing spots for quite awhile.The 405nm
blue laser (same price) is interesting when pot-modded to ~100mw. It makes
some fist-sized crystals I dug out of my rock-shop phosphoresce in a bright
magenta color. As you sweep the laser over the crystals it leaves a trace
of bright magenta for about 1/4th second. This phosphorescence undetectable
under short and long-wave UV. It must be the intensity of the light that
causes it. A pot-modded 405nm laser should be in every rock-hound's bag of
investigative tools. I've no doubt they'll open up a whole new type of
minerals out there now. Categories of short-wave UV
fluorescence/phosphorescence, long-wave UV fluorescence/phosphorescence,
and blue-laser fluorescence/phosphorescence.

What is the crystal? I know fluorite will fluoresce under UV light,
but I don't know which crystals display phosphorescence. Some
sulfides emit light when bombarded by energetic radiation.
http://www.pbase.com/andersonrm/image/103477978


I have a rock that responds this way, I believe it is a Terlingua type
calcite. when hit with either the blue or green laser the whole rock
lights up, looks like it is illuminated from inside.

Well, that sounds like it's only translucent. This rock actually emits its
own bright magenta colored light after it is excited with the blue laser.
Unless that's what you meant. I have some nice museum-quality quartz
crystal masses that look really nice when placed on multi-colored LEDs. Lit
from within like that they are rather impressive looking. (Hand-dug the
crystals out of the hills in the Ozarks on one of my many photo-treks.)

Busy here, but just did a quick experiment in trying to capture the
phosphorescence under blue laser.

http://farm5.static.flickr.com/4075/4888864712_535b2fe4c0_z.jpg
http://farm5.static.flickr.com/4117/4888864716_778a66c2fd_z.jpg


I found it was easiest to just take a video (as suspected) and then grab a
couple good representative frames from the video. Interesting to analyze
the video, after initial excitation by the blue laser, it glows the bright
magenta as seen by the eye, but it rapidly dims to an orange then often a
deep red. The camera was set to daylight balance so there would be no odd
color shifts from auto white-balance, or other. The overexposed area is the
blue-laser, the magenta-orange-red trail is what was left behind as I
played the laser over the large crystal mass (about the size of 2 fists).

To protect the camera's sensor I tried to make sure that no cleavage planes
of the crystals would reflect the blue laser directly back at the camera.
Tilting the crystal mass so that the great majority of all flat surfaces
were at an acute angle away from the camera. Keep this in mind if you find
similar rocks/crystals and attempt the same method to record their
phosphorescence from high-powered (~100mw) blue laser light.

"charles" wrote in message
...
On Tue, 10 Aug 2010 14:05:47 -0700 (PDT), RichA
wrote:

On Aug 9, 8:08 pm, R Davis wrote:
On Mon, 9 Aug 2010 13:51:58 -0700 (PDT), RichA
wrote:

On Aug 9, 4:07 pm, Me wrote:
Alan Browne wrote:
Be careful when using video mode (or long exposures) when lasers
are
around.

http://vimeo.com/13450755

Even worse:

http://www.reuters.com/article/idUSL...080714?sp=true

Brainless to fire a Argon laser into a crowd instead of over their
heads. Even those little frequency-shifted green pocket lasers can do
damage, let alone an industrial entertainment laser.

Especially when they are pot-modded to ~100mw. I had a couple visitors
here
yesterday, their son wanted to play with my 405nm and green laser
pointers
that I have. ($7.95 w/ free shipping from China on E-Bait, but their
potentiometers are adjusted to 5mw to get them through customs.) I
especially like the green pot-modded ones. The beam (not just terminal
dot)
is brightly visible in the air in full sunlight. He was having fun
lighting
matches with them. I warned him to not stare at the focused beam on the
paper-matches too intently. He was seeing spots for quite awhile.The
405nm
blue laser (same price) is interesting when pot-modded to ~100mw. It
makes
some fist-sized crystals I dug out of my rock-shop phosphoresce in a
bright
magenta color. As you sweep the laser over the crystals it leaves a
trace
of bright magenta for about 1/4th second. This phosphorescence
undetectable
under short and long-wave UV. It must be the intensity of the light that
causes it. A pot-modded 405nm laser should be in every rock-hound's bag
of
investigative tools. I've no doubt they'll open up a whole new type of
minerals out there now. Categories of short-wave UV
fluorescence/phosphorescence, long-wave UV fluorescence/phosphorescence,
and blue-laser fluorescence/phosphorescence.

What is the crystal? I know fluorite will fluoresce under UV light,
but I don't know which crystals display phosphorescence. Some
sulfides emit light when bombarded by energetic radiation.
http://www.pbase.com/andersonrm/image/103477978


I have a rock that responds this way, I believe it is a Terlingua type
calcite. when hit with either the blue or green laser the whole rock
lights up, looks like it is illuminated from inside.


I have a rock that I use for weather. the rock is suspended from an old
wooden tripod, by a string. If the rock is white, it's snowing outside. If
the rock is shinning, it's raining; If the rock is moving fast, it's windy.

--
Peter

On Fri, 13 Aug 2010 13:36:16 -0500, R Davis wrote:

On Fri, 13 Aug 2010 00:10:57 -0700, charles
wrote:

On Tue, 10 Aug 2010 14:05:47 -0700 (PDT), RichA
wrote:

On Aug 9, 8:08*pm, R Davis wrote:
On Mon, 9 Aug 2010 13:51:58 -0700 (PDT), RichA
wrote:

On Aug 9, 4:07*pm, Me wrote:
Alan Browne wrote:
Be careful when using video mode (or long exposures) when lasers are
around.

http://vimeo.com/13450755

Even worse:

http://www.reuters.com/article/idUSL...080714?sp=true

Brainless to fire a Argon laser into a crowd instead of over their
heads. *Even those little frequency-shifted green pocket lasers can do
damage, let alone an industrial entertainment laser.

Especially when they are pot-modded to ~100mw. I had a couple visitors here
yesterday, their son wanted to play with my 405nm and green laser pointers
that I have. ($7.95 w/ free shipping from China on E-Bait, but their
potentiometers are adjusted to 5mw to get them through customs.) I
especially like the green pot-modded ones. The beam (not just terminal dot)
is brightly visible in the air in full sunlight. He was having fun lighting
matches with them. I warned him to not stare at the focused beam on the
paper-matches too intently. He was seeing spots for quite awhile.The 405nm
blue laser (same price) is interesting when pot-modded to ~100mw. It makes
some fist-sized crystals I dug out of my rock-shop phosphoresce in a bright
magenta color. As you sweep the laser over the crystals it leaves a trace
of bright magenta for about 1/4th second. This phosphorescence undetectable
under short and long-wave UV. It must be the intensity of the light that
causes it. A pot-modded 405nm laser should be in every rock-hound's bag of
investigative tools. I've no doubt they'll open up a whole new type of
minerals out there now. Categories of short-wave UV
fluorescence/phosphorescence, long-wave UV fluorescence/phosphorescence,
and blue-laser fluorescence/phosphorescence.

What is the crystal? I know fluorite will fluoresce under UV light,
but I don't know which crystals display phosphorescence. Some
sulfides emit light when bombarded by energetic radiation.
http://www.pbase.com/andersonrm/image/103477978


I have a rock that responds this way, I believe it is a Terlingua type
calcite. when hit with either the blue or green laser the whole rock
lights up, looks like it is illuminated from inside.

Well, that sounds like it's only translucent. This rock actually emits its
own bright magenta colored light after it is excited with the blue laser.
Unless that's what you meant. I have some nice museum-quality quartz
crystal masses that look really nice when placed on multi-colored LEDs. Lit
from within like that they are rather impressive looking. (Hand-dug the
crystals out of the hills in the Ozarks on one of my many photo-treks.)

Busy here, but just did a quick experiment in trying to capture the
phosphorescence under blue laser.

http://farm5.static.flickr.com/4075/4888864712_535b2fe4c0_z.jpg
http://farm5.static.flickr.com/4117/4888864716_778a66c2fd_z.jpg


I found it was easiest to just take a video (as suspected) and then grab a
couple good representative frames from the video. Interesting to analyze
the video, after initial excitation by the blue laser, it glows the bright
magenta as seen by the eye, but it rapidly dims to an orange then often a
deep red. The camera was set to daylight balance so there would be no odd
color shifts from auto white-balance, or other. The overexposed area is the
blue-laser, the magenta-orange-red trail is what was left behind as I
played the laser over the large crystal mass (about the size of 2 fists).

To protect the camera's sensor I tried to make sure that no cleavage planes
of the crystals would reflect the blue laser directly back at the camera.
Tilting the crystal mass so that the great majority of all flat surfaces
were at an acute angle away from the camera. Keep this in mind if you find
similar rocks/crystals and attempt the same method to record their
phosphorescence from high-powered (~100mw) blue laser light.

This was interesting. I guess my guesstimate of phosphorescence duration
was pretty close to that 1/4th second. Here's the last bit of video frames
taken at 30 frames per second. From the time the laser first illuminates a
spot on the crystals, until all phosphorescence is no longer visible at
that spot, lasts 7 to 8 frames. 7/30ths to 4/15ths of a second. 1/4th
second falling between the two.

http://www.freepichosting.com/graphic/2010/August/14/326301-Phosphores.gif
Slowed down to make it easier to count the 30ths of a second.

On 10-08-13 2:54 , David J Taylor wrote:
"Kennedy McEwen" wrote in message
...
[]
See this before letting anyone "play" with your cheap green laser
pointer.

http://www.nist.gov/customcf/get_pdf.cfm?pub_id=906138
[]
The document link above explains some simple tests to at least check
the 808nm output from a GLP using a CD-ROM and a webcam.
--
Kennedy

As someone who used to work with NdYAG lasers at 1064nm, with outputs
measured in mega-joules rather than milli-watts, I recall how seriously
the chance of eye damage was taken. Thanks for the pointer to that
document - interesting as a description of how the devices work as well
as for the warning it provides.

Are there goggles that protect against these wavelengths?

--
gmail originated posts are filtered due to spam.

On 10-08-13 21:21 , Peter wrote:

I have a rock that I use for weather. the rock is suspended from an old
wooden tripod, by a string. If the rock is white, it's snowing outside.
If the rock is shinning, it's raining; If the rock is moving fast, it's
windy.

But what's the resolution?

--
gmail originated posts are filtered due to spam.

"Alan Browne" wrote in message
...
[]
Are there goggles that protect against these wavelengths?

Yes, we would be wearing them all the time. Whether they were just
IR-stop, or whether they also had a specific notch at 1.064um I don't
know.

Cheers,
David

"Peter" wrote in message
...
"charles" wrote in message
...
On Tue, 10 Aug 2010 14:05:47 -0700 (PDT), RichA
wrote:

On Aug 9, 8:08 pm, R Davis wrote:
On Mon, 9 Aug 2010 13:51:58 -0700 (PDT), RichA
wrote:

On Aug 9, 4:07 pm, Me wrote:
Alan Browne wrote:
Be careful when using video mode (or long exposures) when lasers
are
around.

http://vimeo.com/13450755

Even worse:

http://www.reuters.com/article/idUSL...080714?sp=true

Brainless to fire a Argon laser into a crowd instead of over their
heads. Even those little frequency-shifted green pocket lasers can do
damage, let alone an industrial entertainment laser.

Especially when they are pot-modded to ~100mw. I had a couple visitors
here
yesterday, their son wanted to play with my 405nm and green laser
pointers
that I have. ($7.95 w/ free shipping from China on E-Bait, but their
potentiometers are adjusted to 5mw to get them through customs.) I
especially like the green pot-modded ones. The beam (not just terminal
dot)
is brightly visible in the air in full sunlight. He was having fun
lighting
matches with them. I warned him to not stare at the focused beam on the
paper-matches too intently. He was seeing spots for quite awhile.The
405nm
blue laser (same price) is interesting when pot-modded to ~100mw. It
makes
some fist-sized crystals I dug out of my rock-shop phosphoresce in a
bright
magenta color. As you sweep the laser over the crystals it leaves a
trace
of bright magenta for about 1/4th second. This phosphorescence
undetectable
under short and long-wave UV. It must be the intensity of the light
that
causes it. A pot-modded 405nm laser should be in every rock-hound's bag
of
investigative tools. I've no doubt they'll open up a whole new type of
minerals out there now. Categories of short-wave UV
fluorescence/phosphorescence, long-wave UV
fluorescence/phosphorescence,
and blue-laser fluorescence/phosphorescence.

What is the crystal? I know fluorite will fluoresce under UV light,
but I don't know which crystals display phosphorescence. Some
sulfides emit light when bombarded by energetic radiation.
http://www.pbase.com/andersonrm/image/103477978


I have a rock that responds this way, I believe it is a Terlingua type
calcite. when hit with either the blue or green laser the whole rock
lights up, looks like it is illuminated from inside.


I have a rock that I use for weather. the rock is suspended from an old
wooden tripod, by a string. If the rock is white, it's snowing outside. If
the rock is shinning, it's raining; If the rock is moving fast, it's
windy.

If you can't see the rock it's foggy

On Sat, 14 Aug 2010 11:11:44 -0400, Alan Browne
wrote:

On 10-08-13 21:21 , Peter wrote:

I have a rock that I use for weather. the rock is suspended from an old
wooden tripod, by a string. If the rock is white, it's snowing outside.
If the rock is shinning, it's raining; If the rock is moving fast, it's
windy.

But what's the resolution?

Oh look. The thread-hijacking, off-topic, pretend-photographer, resident
trolls aren't getting enough attention again. That's so sad. Awwww..... :-(

On 10-08-14 12:22 , OG wrote:
wrote in message

I have a rock that I use for weather. the rock is suspended from an old
wooden tripod, by a string. If the rock is white, it's snowing outside. If
the rock is shinning, it's raining; If the rock is moving fast, it's
windy.

If you can't see the rock it's foggy

Or dusty. Or there's saltspray on the windows. This is an area of many
criticisms of the rock wx system

--
gmail originated posts are filtered due to spam.

OG wrote:
"Peter" wrote in message

[removed 67 lines. Why can't you all just keep what you all
reply to?]

I have a rock that I use for weather. the rock is suspended from an old
wooden tripod, by a string. If the rock is white, it's snowing outside. If
the rock is shinning, it's raining; If the rock is moving fast, it's
windy.

If you can't see the rock it's foggy

If the rock fell down, it's an earthquake.

-Wolfgang