DVD laser (just out of curiosity).

I

Ian Field

Guest
Is a DVD laser orange/amber?

Someone tossed an old DVD player in the bins at the flats, so I decided to
investigate its salvage potential, the laser is a proper-job TO18 style
pressed into a block of aluminium - seems a bit extravegant since it was
only a player, not a recorder.

There's some websites out there demonstrating lighting matches & burning
holes through paper with a DVD laser, but I presume they're using a recorder
laser for that much power.

Before I start waving the soldering iron at it - can anyone suggest a
"ball-park figure" for laseing current?

Thanks.
 
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:kcnf52$ojp$1@dont-email.me...
Is a DVD laser orange/amber?

It's (supposedly) red. But there would be nothing wrong using a shorter
wavelength.
Click to expand...

Someone on ABSE once told me the wavelength, when I looked it up on a chart
it came out as amber-ish or thereabouts.

Apparently the IR long wavelength is the limiting factor for data density on
a CD - I'd expect somewhere more in the general direction of orange than
visible red for DVD, but as yet I've never fired up a DVD or CD laser.

This is the first optical drive laser I've recued that actually had proper
encapsulation.
 
This article says the DVD wavelength is 650nm, and calls it "red".

http://en.wikipedia.org/wiki/Optical_disc_drive

However, I find that a bit on the short side for red.
 
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:kcnj8h$gml$1@dont-email.me...
This article says the DVD wavelength is 650nm, and calls it "red".

http://en.wikipedia.org/wiki/Optical_disc_drive

However, I find that a bit on the short side for red.
Click to expand...
A 'standard' consumer DVD laser is bright red at around 650 nm wavelength. I
have never seen one tending towards amber, or indeed any shade of yellow. A
CD laser is infra red at around 780 nm wavelength. On the other hand, the
laser fitted to a Blu Ray DVD player is just that - blue - and has a much
shorter wavelength at just over 400 nm. The reason for each wavelength
becoming shorter as you go from CD to Blu ray, is that each disc type packs
more data on its playing surface(s) and it does this by using ever smaller
pits and lands. In order to resolve these, shorter and shorter wavelength
lasers are required ...

Arfa
 
On 1/10/2013 1:41 PM, Ian Field wrote:
Is a DVD laser orange/amber?

Someone tossed an old DVD player in the bins at the flats, so I decided
to investigate its salvage potential, the laser is a proper-job TO18
style pressed into a block of aluminium - seems a bit extravegant since
it was only a player, not a recorder.

There's some websites out there demonstrating lighting matches & burning
holes through paper with a DVD laser, but I presume they're using a
recorder laser for that much power.

Before I start waving the soldering iron at it - can anyone suggest a
"ball-park figure" for laseing current?

Thanks.
Just a quick reminder not to do anything stupid.
Click to expand...
Those yellow stickers are on there for a reason.

Reminds me of a sign on the wall at the laser lab....

Caution! Do not look into laser with remaining good eye...
 
"William Sommerwanker is an Ass"
Is a DVD laser orange/amber?

It's (supposedly) red. But there would be nothing wrong using a shorter
wavelength.
Click to expand...
** Utter bullshit.

Wavelength is critical to reading the data from a pressed disk.


.... Phil
 
"Phil Allison" wrote in message news:al9ekjFs5geU1@mid.individual.net...
"William Sommerwanker is an Ass"

Is a DVD laser orange/amber?

It's (supposedly) red. But there would be nothing wrong
using a shorter wavelength.

Utter bullshit.
Wavelength is critical to reading the data from a pressed disk.
Click to expand...
A short wavelength is needed to resolve fine detail. There's nothing wrong
with using a blue laser to read a CD.
 
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:kcp18m$av9$1@dont-email.me...
"Phil Allison" wrote in message news:al9ekjFs5geU1@mid.individual.net...
"William Sommerwanker is an Ass"

Is a DVD laser orange/amber?

It's (supposedly) red. But there would be nothing wrong
using a shorter wavelength.

Utter bullshit.
Wavelength is critical to reading the data from a pressed disk.

A short wavelength is needed to resolve fine detail. There's nothing wrong
with using a blue laser to read a CD.
Click to expand...
I don't think that you will find that is true - at least in my experience.
Although the physical optics of the optical block - i.e. the lens etc - may
be common for both formats, there is actually two laser diodes in a DVD
optical block, an IR one for reading CDs, and a visible red for reading
DVDs. In a Blu Ray optical block, there are three laser diodes, IR, vis red
and blue. Often, there are two sets of optics on these as well, which
manifests to the outside world as two lenses. If one short wave laser could
be used to read all three formats, the manufacturers would not waste money
and complexity to have a three-diode block.

You may find this informative

http://repairfaq.cis.upenn.edu/Misc/Blu-ray/site1/optics.html

Arfa
 
A short wavelength is needed to resolve fine detail. There's nothing
wrong with using a blue laser to read a CD.
Click to expand...

I don't think that you will find that is true - at least in my experience.
Although the physical optics of the optical block - i.e. the lens etc - may
Click to expand...
be common for both formats, there is actually two laser diodes in a DVD
optical block, an IR one for reading CDs, and a visible red for reading
DVDs. In a Blu Ray optical block, there are three laser diodes, IR, vis red
and blue. Often, there are two sets of optics on these as well, which
manifests to the outside world as two lenses. If one short wave laser could
be used to read all three formats, the manufacturers would not waste money
and complexity to have a three-diode block.

I stand by what I said. There is nothing at all wrong with using a blue laser
to read a CD. I did not say that a single optical block for all formats is
desirable -- now, did I?

The //practical// consideration is that shorter-wavelength lasers are set to
focus closer to the surface of the disk. It's probably simpler to have
multiple blocks, each optimized for the format to be played.
 
A short wavelength is needed to resolve fine detail. There's nothing
wrong with using a blue laser to read a CD.
Click to expand...

I don't think that you will find that is true - at least in my experience.
Although the physical optics of the optical block - i.e. the lens etc - may
Click to expand...
be common for both formats, there is actually two laser diodes in a DVD
optical block, an IR one for reading CDs, and a visible red for reading
DVDs. In a Blu Ray optical block, there are three laser diodes, IR, vis red
and blue. Often, there are two sets of optics on these as well, which
manifests to the outside world as two lenses. If one short wave laser could
be used to read all three formats, the manufacturers would not waste money
and complexity to have a three-diode block.

I stand by what I said. There is nothing at all wrong with using a blue laser
to read a CD. I did not say that a single optical block for all formats is
desirable -- now, did I?

The //practical// consideration is that shorter-wavelength lasers are set to
focus closer to the surface of the disk. It's probably simpler to have
multiple blocks, each optimized for the format to be played.
 
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:kcph7a$9p4$2@dont-email.me...
A short wavelength is needed to resolve fine detail. There's nothing
wrong with using a blue laser to read a CD.


I don't think that you will find that is true - at least in my
experience.
Although the physical optics of the optical block - i.e. the lens etc -
may
be common for both formats, there is actually two laser diodes in a DVD
optical block, an IR one for reading CDs, and a visible red for reading
DVDs. In a Blu Ray optical block, there are three laser diodes, IR, vis
red
and blue. Often, there are two sets of optics on these as well, which
manifests to the outside world as two lenses. If one short wave laser
could
be used to read all three formats, the manufacturers would not waste money
and complexity to have a three-diode block.

I stand by what I said. There is nothing at all wrong with using a blue
laser
to read a CD. I did not say that a single optical block for all formats is
desirable -- now, did I?

The //practical// consideration is that shorter-wavelength lasers are set
to
focus closer to the surface of the disk. It's probably simpler to have
multiple blocks, each optimized for the format to be played.
Click to expand...
Well, I would have to say that you are going off on one of your word-play
exercises there. I also stand by what I said. I didn't say that you
*couldn't* read a CD or DVD with a blue laser, although I am not
sufficiently versed in the deep nuts and bolts of the technology to know
that for sure. I was actually responding to your contention that there is
"nothing wrong" with using a blue laser. Clearly there is something wrong
with doing so, otherwise in the real commercial world, major manufacturers
like Sony would do it. It's not a case of desirable, or otherwise. It's a
case of cold hard cash.

Arfa
 
"mike" <ham789@netzero.net> wrote in message
news:kcnrlj$ue3$1@dont-email.me...
On 1/10/2013 1:41 PM, Ian Field wrote:
Is a DVD laser orange/amber?

Someone tossed an old DVD player in the bins at the flats, so I decided
to investigate its salvage potential, the laser is a proper-job TO18
style pressed into a block of aluminium - seems a bit extravegant since
it was only a player, not a recorder.

There's some websites out there demonstrating lighting matches & burning
holes through paper with a DVD laser, but I presume they're using a
recorder laser for that much power.

Before I start waving the soldering iron at it - can anyone suggest a
"ball-park figure" for laseing current?

Thanks.
Just a quick reminder not to do anything stupid.
Those yellow stickers are on there for a reason.

Reminds me of a sign on the wall at the laser lab....

Caution! Do not look into laser with remaining good eye...
Click to expand...
Apparently green lasers are worst - maximum absorbtion by hemoglobin.
 
On 01/10/2013 06:35 PM, William Sommerwerck wrote:
This article says the DVD wavelength is 650nm, and calls it "red".

http://en.wikipedia.org/wiki/Optical_disc_drive

However, I find that a bit on the short side for red.
Click to expand...
650 is a pretty good red. The photopic sensitivity curve rolls off to
about zilch past 700, so there isn't that much redder to be had. Ruby
lasers are about 694 nm, but they're _bright_.

A red HeNe laser is 632.8 nm.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net
 
On 1/11/2013 10:11 AM, Ian Field wrote:
"mike" <ham789@netzero.net> wrote in message
news:kcnrlj$ue3$1@dont-email.me...
On 1/10/2013 1:41 PM, Ian Field wrote:
Is a DVD laser orange/amber?

Someone tossed an old DVD player in the bins at the flats, so I decided
to investigate its salvage potential, the laser is a proper-job TO18
style pressed into a block of aluminium - seems a bit extravegant since
it was only a player, not a recorder.

There's some websites out there demonstrating lighting matches & burning
holes through paper with a DVD laser, but I presume they're using a
recorder laser for that much power.

Before I start waving the soldering iron at it - can anyone suggest a
"ball-park figure" for laseing current?

Thanks.
Just a quick reminder not to do anything stupid.
Those yellow stickers are on there for a reason.

Reminds me of a sign on the wall at the laser lab....

Caution! Do not look into laser with remaining good eye...


Apparently green lasers are worst - maximum absorbtion by hemoglobin.
Click to expand...
I'd argue with that as a practical matter...assuming your intent is to
avoid blindness.
People tend to stare longer at invisible lasers than ones that seem
damagingly bright to them. By the time you perceive the effects of
an invisible laser, it's too late.
 
"mike" <ham789@netzero.net> wrote in message
news:kcq0q3$cjk$1@dont-email.me...
On 1/11/2013 10:11 AM, Ian Field wrote:


"mike" <ham789@netzero.net> wrote in message
news:kcnrlj$ue3$1@dont-email.me...
On 1/10/2013 1:41 PM, Ian Field wrote:
Is a DVD laser orange/amber?

Someone tossed an old DVD player in the bins at the flats, so I decided
to investigate its salvage potential, the laser is a proper-job TO18
style pressed into a block of aluminium - seems a bit extravegant since
it was only a player, not a recorder.

There's some websites out there demonstrating lighting matches &
burning
holes through paper with a DVD laser, but I presume they're using a
recorder laser for that much power.

Before I start waving the soldering iron at it - can anyone suggest a
"ball-park figure" for laseing current?

Thanks.
Just a quick reminder not to do anything stupid.
Those yellow stickers are on there for a reason.

Reminds me of a sign on the wall at the laser lab....

Caution! Do not look into laser with remaining good eye...


Apparently green lasers are worst - maximum absorbtion by hemoglobin.

I'd argue with that as a practical matter...assuming your intent is to
avoid blindness.
People tend to stare longer at invisible lasers than ones that seem
damagingly bright to them. By the time you perceive the effects of
an invisible laser, it's too late.
Click to expand...
Challenge someone to observe the dull red glow on an IR laser chip.
 
"mike" wrote in message news:kcq0q3$cjk$1@dont-email.me...

On 1/11/2013 10:11 AM, Ian Field wrote:
"mike" <ham789@netzero.net> wrote in message
news:kcnrlj$ue3$1@dont-email.me...
On 1/10/2013 1:41 PM, Ian Field wrote:
Is a DVD laser orange/amber?

Someone tossed an old DVD player in the bins at the flats, so I decided
to investigate its salvage potential, the laser is a proper-job TO18
style pressed into a block of aluminium - seems a bit extravegant since
it was only a player, not a recorder.

There's some websites out there demonstrating lighting matches & burning
holes through paper with a DVD laser, but I presume they're using a
recorder laser for that much power.

Before I start waving the soldering iron at it - can anyone suggest a
"ball-park figure" for laseing current?

Thanks.
Just a quick reminder not to do anything stupid.
Those yellow stickers are on there for a reason.

Reminds me of a sign on the wall at the laser lab....

Caution! Do not look into laser with remaining good eye...


Apparently green lasers are worst - maximum absorbtion by hemoglobin.
Click to expand...
I'd argue with that as a practical matter...assuming your intent is to
avoid blindness.
People tend to stare longer at invisible lasers than ones that seem
damagingly bright to them. By the time you perceive the effects of
an invisible laser, it's too late.




Can you link to any data that shows how many people have been blinded by CD
lasers?

Gareth.
 
Can you link to any data that shows how many people
have been blinded by CD lasers?
Click to expand...
I suspect it's zero. The output of a CD playback laser is only a few
milliwatts, I believe. It would to blind someone with that.
 
"William Sommerwanker is a Fucking Ass"

Is a DVD laser orange/amber?

It's (supposedly) red. But there would be nothing wrong
using a shorter wavelength.

Utter bullshit.

Wavelength is critical to reading the data from a pressed disk.

A short wavelength is needed to resolve fine detail.
Click to expand...

** ROTFL !!

What a fucking MORON and NUT CASE.

FYI

the pit depth on pressed disks is half a wavelength in each case.

DVD players have both IR and red lasers.



..... Phil
 
"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:alc37bFfu6tU1@mid.individual.net...
"William Sommerwanker is a Fucking Ass"

Is a DVD laser orange/amber?

It's (supposedly) red. But there would be nothing wrong
using a shorter wavelength.

Utter bullshit.

Wavelength is critical to reading the data from a pressed disk.

A short wavelength is needed to resolve fine detail.


** ROTFL !!

What a fucking MORON and NUT CASE.

FYI

the pit depth on pressed disks is half a wavelength in each case.

DVD players have both IR and red lasers.



.... Phil
Click to expand...
Indeed, Phil. And as I said in my reply to William, Blu Ray players have a
blue one as well ...

If the pits are indeed a half wavelength deep, then that is the answer to
why all three laser wavelengths are required to read all three formats, and
why the likes of Sony go to all that trouble to integrate three different
laser diodes into one block.

Arfa
 
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