Laserdisc player with sharpest image
Riccardo
the sharpest and most detailed image ever?
unclejr
> Hello to everybody! Which is in your opinion the laserdisc player with
> the sharpest and most detailed image ever?
Through the s-video or through the composite output?
It is generally believed that for s-video, it's the HLD-X9 and for
composite, it's the HLD-X0.
If you're talking about American players, then for s-video, maybe the
CLD-99 and for composite the LD-S2. However, I've heard good reviews
for composite output for both the CLD-95 and CLD-97 players.
-Junior
Kevin Hawerchuk
extremely sharp pictures, as well as the old CLD 1010 model, which used
a red laser diode.
These players are so sharp that they can show every flaw, speckle,
white-line dropout, ect, that's on the disc.
I remember I once had the top Phillips player(model escapes me) and I
compared it with a D703. Laserdisc defects that were invisible on the
Phillips showed up clearly on the D703.
Thad Floryan
Continuing in this vein, my vote is for the HLD-X9. Because of
its shorter-wavelength red laser diode (670 nm) it could play
rotted LDs that could not be played on a CLD-704 or CLD-99 whose
laser wavelengths are 780 nm (IR).
For comparison, the blue laser for HD DVD is 405 nm and the red
laser for standard DVDs is 635-650 nm.
torsten
players (e.g. LD-1000 series), with the HeNe laser. I believe the PQ
they produce is very close to what is stamped on the LD as there is
almost no electronics between the pickup and video output jacks :)
Whether one can accept the disadvantages of those dinosaurs is another
story.
Riccardo
Well, I didn't think of any of the two specifically. As far as I know,
the video track recorded on a LD is composite, so we can assume that
the composite output has less modification of the signal than the s-
video one, then a higher fidelity and/or quality, then a sharper
image. But I cannot tell that for sure, because I am not an expertise,
when it comes to Laserdisc players.
> If you're talking about American players
As a matter of fact, I was generally talking. Again, as far as I know,
American players can only player NTSC LD, while European ones can play
both. So there could be a PAL player that has the sharpest image ever
when playing PAL discs, but there could be also a NTSC player that
defeats it when it comes to NTSC discs!
So my starting question could be splitted in two:
1) Which is in your opinion the laserdisc player with the sharpest and
most detailed NTSC image ever?
2) Which is in your opinion the laserdisc player with the sharpest and
most detailed PAL image ever?
> Continuing in this vein, my vote is for the HLD-X9. Because of
> its shorter-wavelength red laser diode (670 nm) it could play
> rotted LDs that could not be played on a CLD-704 or CLD-99 whose
> laser wavelengths are 780 nm (IR).
> For comparison, the blue laser for HD DVD is 405 nm and the red
> laser for standard DVDs is 635-650 nm.
Higher values for wavelenght mean lower values for frequency. Is there
any chance that a lower frequencied laser has a less wide bandwidth?
> As Thad said, I'd like to bring up the non-obvious: the 1st gen
> players (e.g. LD-1000 series), with the HeNe laser. I believe the PQ
> they produce is very close to what is stamped on the LD as there is
> almost no electronics between the pickup and video output jacks :)
So they have a higher fidelity, but in case their laser has a less
wide bandwidth, they could have a softened and less detailed image,
couldn't they?
Nico de Vries
Here's my bit. All is based on actual experiences with the players
mentioned:
PAL, composite: Pioneer CLD-1050 (PAL version of the CLD-1010)
PAL, RGB: Philips LDP-600WS (beats everything in PAL, no auto reverse or
digital frame memory though)
NTSC, composite: 1. Elite LD-S2/LD-X1
2. Elite CLD-97/CLD-98
3. Elite CLD-99
NTSC, RGB: Philips LDP-600WS
Composite versus S-video is always dependent on the display/projector used,
sometimes composite is better, sometimes S-video. Just try if player and
display have both connections.
Note that there exists an NTSC-only version of the Philips LDP-600WS which
also has digital frame memory. No actual experiences with this one though.
Regarding red versus infra-red laser pickups: keep in mind that the
Laserdisc system was originally developed using red HeNe laser tubes. In
theory a red laser is better, and it is frequently reported that players
having red lasers play marginal/rotted LD's better that the ones with
infra-red lasers.
Where the rumor comes from I don't know, but the CLD-1010/CLD-1050 do NOT
have a red laser, as they play CD's with the same pickup. The latter fact
is impossible with a read laser. My CLD-1050 does not produce visible light
from the pickup when playing an LD.
Regards,
Nico de Vries
"Riccardo" <r_rom...@hotmail.com> wrote in message
news:4a1e9c7f-b57f-4c77...@w9g2000yqa.googlegroups.com...
Thad Floryan
> > [...]
> > Continuing in this vein, my vote is for the HLD-X9. Because of
> > its shorter-wavelength red laser diode (670 nm) it could play
> > rotted LDs that could not be played on a CLD-704 or CLD-99 whose
> > laser wavelengths are 780 nm (IR).
> > For comparison, the blue laser for HD DVD is 405 nm and the red
> > laser for standard DVDs is 635-650 nm.
>
> Higher values for wavelenght mean lower values for frequency. Is there
> any chance that a lower frequencied laser has a less wide bandwidth?
That would violate physics. :-)
Same thing with "processes" used for semiconductors to get ever
smaller structures on the dies; higher frequency = smaller wavelengths
to achieve the smaller structures.
Infrared (lower frequency) is "broader" than visible red which is
"broader" than violet which is "broader" than ultraviolet.
cfca...@gmail.com
>
> Higher values for wavelenght mean lower values for frequency. Is there
> any chance that a lower frequencied laser has a less wide bandwidth?
>
>
> wide bandwidth, they could have a softened and less detailed image,
> couldn't they?
As a matter of fact, the frequency is irrelevant, since the
information is encoded not into the beam, but into the disc, & the on-
off modulation produced on the beam by the disc is of a much lower
frequency than even the infrared laser beam -- a few million cycles
per second (MHz), as opposed to hundreds of trillions (THz).
What is important is "Abbe's Law", a law of optics which shows that
the spot size resolvable by an optical assembly is related to the lens
& the wavelength of the light used. The shorter the wavelength, the
smaller the spot. The smaller the spot resolved, the more clearly the
pickup can "see" the pits impressed on the disc, and the better
quality signal reaches the demodulating & decoding electronics.
--publius--
Thad Floryan
> [...]
> Where the rumor comes from I don't know, but the CLD-1010/CLD-1050 do NOT
> have a red laser, as they play CD's with the same pickup. The latter fact
> is impossible with a read laser. My CLD-1050 does not produce visible light
> from the pickup when playing an LD.
Scratching my head here. What did you mean by "latter fact is
impossible with a read laser"?
If "read laser" is a typo for "red laser" (typos happen :-), a
red laser would have no problems reading something intended to be
read by an IR laser. That's how the HLD-X9 reads standard LDs.
Riccardo
> > any chance that a lower frequencied laser has a less wide bandwidth?
>
Not at all! But I have to admit that I wrote sentences in an English
that is not that good (English is not my language). Now I am gonna try
to rephrase them. As far as I know, LDs contain analog video. If that
is true, then we should NOT be talking about ON-OFF modulation, we
should be talking about some other analog modulation, instead. When it
comes to lasers for TRANSMISSIONS, when it is an analog modulation,
you have a laser's emission frequency (lower when infrared and higher
when red) AND a bandwidth that is CENTERED on the emission frequency.
The bandwidth is given by laser modulabilty, NOT by emission
frequency, even though it COULD be possible that laser's central
emission frequency has something to do with bandwidth because it COULD
be easier to achive best modulability in a laser having a lower
central emission frequency, but the opposite COULD be possible as
well, I don't know. The broader is the bandwidth, the broader is the
signal's bandwidth it can transmit. Anyhow, we were not talking about
transmission, we were talking about reading tracks on discs, so what I
stated earlier should be best referred to the whole optical assembly
and I guess that in this case the width of the bandwidth should be
best given by the optical sensor (photodiode?). The broader is the
bandwidth the optical assembly has, the broader is the signal's
bandwidth it can read and demodulate (to achive 425 lines for
horizontal resolution, you should have about 5 MHz bandwidth for PAL
video).
cfca...@gmail.com
> Not at all! But I have to admit that I wrote sentences in an English
> that is not that good (English is not my language). Now I am gonna try
> to rephrase them. As far as I know, LDs contain analog video. If that
> is true, then we should NOT be talking about ON-OFF modulation, we
> should be talking about some other analog modulation, instead. When it
> comes to lasers for TRANSMISSIONS, when it is an analog modulation,
> you have a laser's emission frequency (lower when infrared and higher
> when red) AND a bandwidth that is CENTERED on the emission frequency.
> The bandwidth is given by laser modulabilty, NOT by emission
> frequency, even though it COULD be possible that laser's central
> emission frequency has something to do with bandwidth because it COULD
> be easier to achive best modulability in a laser having a lower
> central emission frequency, but the opposite COULD be possible as
> well, I don't know. The broader is the bandwidth, the broader is the
> signal's bandwidth it can transmit. Anyhow, we were not talking about
> transmission, we were talking about reading tracks on discs, so what I
> stated earlier should be best referred to the whole optical assembly
> and I guess that in this case the width of the bandwidth should be
> best given by the optical sensor (photodiode?). The broader is the
> bandwidth the optical assembly has, the broader is the signal's
> bandwidth it can read and demodulate (to achive 425 lines for
> horizontal resolution, you should have about 5 MHz bandwidth for PAL
> video).
You can have analog on-off modulation, and that's what LaserDisc
uses. The fundamental encoding of the video is frequency-
modulation ; since all the information in a FM signal is contained in
the zero-crossings, it is possible to write it to a series of on-off
states of varying length, represented by the pits and lands pressed
into the disc. An additional pulse-width modulation is added to
represent the audio information. These physical indentations are
swept past the the focussed beam spot at high speed, producing bilevel
amplitude modulation of the reflected beam. There is no frequency
deviation of the laser light itself, and the bandwidth of the
sidebands is miniscule compared to the fundamental frequency of the
beam. The pickup deconvolves the bilevel amplitude modulation to
reconstruct the modulated RF carrier, a low-pass filter picks off the
audio information which goes to its demodulator, and the remainder of
the signal is demodulated to video.
Theoretical frequency response is determined by the minimum pit or
land length and the speed at which the pits and lands pass the pickup
spot. Actual frequency response depends on the focussed spot size,
which determines the minimum resolvable pit size, the contrast level
of different-sized pits, and the sharpness of the on-off transitions.
This spot size is determined, per Abbe's Law, by the light wavelength
and the lens numerical aperture. For NTSC or PAL discs, the peak
frequency in the FM sidebands is roughly 12.5 MHz. For MUSE, the peak
frequency is above 18 MHz. As a result, the MUSE pickup must be able
to read the smaller spot size, and the demodulation electronics of
must give a correspondingly wider bandpass, so the MUSE player
produces a higher-quality signal from NTSC discs.
--publius--
Thad Floryan
I believe I see what you're getting at. About 10+ years ago, someone
(Rob Niland ?) posted technical details how it works.
As you may know, contrasted to CDs and DVDs, LDs have variable
length pits and lands and, IIRC, this is a frequency modulation
scheme in which all the LD info is encoded/decoded. If you look
at the opening splash on many older Image (the company) LDs, you'll
see a representation of the variable length pits and lands.
The laser frequency does not change under any circumstances; it
physically cannot because the frequency is a function of the
materials used (gallium, arsenide, etc. in solid-state lasers).
What changes is the period of it being on and off; that's the
modulation for "burning" an LD and what's detected when reading
it during playback due to the varying length pits and lands.
Check these out (Google using "how it works laserdisc"):
<http://www.dts-l.org/watch/t-Nua2kku0c/eyeh8cbs/laserdisc:-how-it-
works.html>
<http://www.youtube.com/watch?v=t-Nua2kku0c>
<http://communication.howstuffworks.com/analog-digital.htm>
<http://en.wikipedia.org/wiki/Laserdisc>
Thad Floryan
> [...]
> I believe I see what you're getting at. About 10+ years ago, someone
> (Rob Niland ?) posted technical details how it works.
Here's Bob Niland's LD FAQs:
<http://www.access-one.com/rjn/laser/laserdisc.html>
Other good information:
<http://www.blamld.com/Laserdisc/FAQ/>
<http://www.blamld.com/LaserDisc/FAQ/FAQ_Hardware.htm>
<http://www.access-one.com/rjn/laser/legacy/ld96.html>
<http://www.fixya.com/support/t167606-laserdisc_info_please>
<http://www.modeemi.fi/~leopold/AV/LdFaq/>
and there's even some info here:
<http://thadlabs.com/LD_info/>
:-)
Thad Floryan
Since I had it (snagged from YouTube), the 24.8 MB FLV video of
Don Herbert (TV's "Mr. Wizard") describing how laserdiscs work
is now available:
<http://thadlabs.com/LD_info/how_laserdisks_work_Don_Herbert.flv>
It can also be viewed directly from the LD_info page if you have
a browser-known player that can play FLV videos. The video runs
10:29 and I'm guessing it was made in 1978. Sadly, Don Herbert
died in 2007. I used to watch his programs back in the 1950s.
Thad Floryan
> On Mar 14, 2:04 pm, Thad Floryan <t...@thadlabs.com> wrote:
>
> > [...]
> > and there's even some info here:
>
> > <http://thadlabs.com/LD_info/>
>
> Since I had it (snagged from YouTube), the 24.8 MB FLV video of
> Don Herbert (TV's "Mr. Wizard") describing how laserdiscs work
> is now available:
>
> <http://thadlabs.com/LD_info/how_laserdisks_work_Don_Herbert.flv>
Oops; typo. The URL is:
<http://thadlabs.com/LD_info/how_laserdiscs_work_Don_Herbert.flv>
rjn
> The laser frequency does not change under any circumstances; it
> physically cannot because the frequency is a function of the
> materials used (gallium, arsenide, etc. in solid-state lasers).
Tunable lasers are available. They might actually be of
use in multi-format players. Whether or not any are so used
is not known to me.
> What changes is the period of it being on and off; that's the
> modulation for "burning" an LD and what's detected when reading
> it during playback due to the varying length pits and lands.
In taking another look at IEC-857, the NTSC LV spec, it calls
for a specific laser frequency (6328A, 633nm), numerical
aperture (0.40) and index of refraction/thickness envelope.
It also specifies the cross section and diffraction rings
of the readout beam, and reflectivity (>70%) of the medium,
without specifying whether land or pit.
Curiously, other than track pitch (1.4-2um) it says nothing
about pit geometry (shape, width, depth, or whether incuse
or relief), nor even the ratio of pit/land reflectivity.
One has to consult other sources to discover that stamped
and cast LDs are probably using a pit that is 103nm deep
and 400nm wide.
103nm is 1/4 wavelength of the 633nm laser light, accounting
for refraction. If half the light is reflected by the pit,
and half by the land, the result is signal cancellation
at pits, and full reflection at lands. The pits appear
"black" to the detector. Elegant.
Presumably the IEC spec was vague on this to allow for
totally non-reflective (actually black) pits, which
could be any depth or size, or no depth at all.
In any event, the pit is either there or not (1/0),
but how long it's there, and how long it's there
relative to the adjacent land, are arbitrary (analog).
LD is analog because my zero is longer than your zero.
And since the majority of discs in the wild are made
on the 1/4 wavelength reflectivity principle, any
laser with a materially different wavelength may
have to have to use some other means of detecting
pits. If you can play a vinyl LP with a laser, this is
obviously possible.
How much different can the wavelength be? I don't
really know. However, after the IEC-857 spec was written,
LV switched to laser diodes and added CD playback
(which calls for a 780nm source). So it could be that
typical LD players are not actually using a 6328A source.
Is using a laser wavelength substantially different
from 6328A/633nm necessarily beneficial in playback
of LDs? That's not at all clear to me.
--
Regards, Bob Niland mailto:na...@ispname.tld
http://www.access-one.com/rjn email4rjn AT yahoo DOT com
NOT speaking for any employer, client or Internet Service Provider.
Borked Pseudo Mailed
links didn't work, but you posted the correct URLs earlier. All great
information. The Don Herbert video was really cool.
The last place to sells discs in my area was a store on El Camino in
Mountain View, CA. It moved three times, each store smaller than the last,
the laserdisc racks got thinner and the DVD displays larger. The woman who
ran the place was still holding onto a lot of the good rental titles as she
claimed people from Stanford University used her discs for research. At
some point reality set in and she let those discs sell also. The last time
I went to the store was 3 years ago, they were now next to an Indian
restaurant, very hard to locate. They were running an ad on Craigslist,
advertsing they were selling all their titles. It was pretty well picked
over. What remained were the really bad movies nobody had wanted to buy
for the past 10 years. I don't know if they are in business today.
Thad Floryan
wrote:
> Thanks Thad for posting the great links to the newsgroup. Your web page FAQ
> links didn't work, but you posted the correct URLs earlier. All great
> information. The Don Herbert video was really cool.
You're welcome! I really need to update the LD_info page. The only
updates in 10 years were the corrected Bizarro cartoon last year and
the addition of the Don Herbert video yesterday.
Working for startups doesn't leave much free time, so I'm resigned to
using a "TV table tray" for eating dinner and watching movies at the
same time. And the last company I worked for went belly-up last year
so now I have even less free time while looking for work.
> The last place to sells discs in my area was a store on El Camino in
> Mountain View, CA. It moved three times, each store smaller than the last,
> the laserdisc racks got thinner and the DVD displays larger. The woman who
> ran the place was still holding onto a lot of the good rental titles as she
> claimed people from Stanford University used her discs for research. At
> some point reality set in and she let those discs sell also. The last time
> I went to the store was 3 years ago, they were now next to an Indian
> restaurant, very hard to locate. They were running an ad on Craigslist,
> advertsing they were selling all their titles. It was pretty well picked
> over. What remained were the really bad movies nobody had wanted to buy
> for the past 10 years. I don't know if they are in business today.
Yes, I remember that company, at the corner of El Camino and San
Antonio.
It was named Videoscope, and their old website was:
<http://www.videoscope.formovies.com>
and, surprise, it still exists as:
<http://videoscope.formovies.com/search/store.html?postal_code=94022>
One young lady who used to frequent this group and who I'd often
encounter at both Videoscope and Laserland (in Cupertino/San Jose)
was able to snag a copy of SONG OF THE SOUTH at Videoscope. I must
have missed getting it by only hours. Such is life. :-)
I haven't checked in a few years to see if Laserland still exists.
As I recall, they ran into financial problems as Web and discount
store sales of DVDs curtailed their clientele. That was a shame
because they had over 10,000 titles in stock on the floor and is
where I'd find stuff available nowhere else. But their pricing
was retail level, not discounted, and most customers shop for
lowest price.
Thad Floryan
> [...]
> In taking another look at IEC-857, the NTSC LV spec, it calls
> for a specific laser frequency (6328A, 633nm), numerical
> aperture (0.40) and index of refraction/thickness envelope.
> It also specifies the cross section and diffraction rings
> of the readout beam, and reflectivity (>70%) of the medium,
> without specifying whether land or pit.
Now you've piqued my curiousity. 633nm is the realm of lasers
used for DVDs. Is that what IEC-857 addresses?
> [...]
> Is using a laser wavelength substantially different
> from 6328A/633nm necessarily beneficial in playback
> of LDs? That's not at all clear to me.
The claimed laser wavelength of, for example, a CLD-D704
and CLD-99, is 780nm, and 670nm for the HLD-X9, so I'm
puzzled where the 633nm comes into the picture.
For what it's worth, several rotted LDs that could not be
played on my CLD-D704 and CLD-99 would play, albeit with
some video noise, on my HLD-X9, so that suggests the finer
laser beam (670nm) contributes to that playability.
Thad Floryan
> On Mar 15, 8:37 am, Borked Pseudo Mailed <nob...@pseudo.borked.net>
> wrote:
>
> > Thanks Thad for posting the great links to the newsgroup. Your web page FAQ
> > links didn't work, but you posted the correct URLs earlier. All great
> > information. The Don Herbert video was really cool.
>
> You're welcome! I really need to update the LD_info page. The only
> updates in 10 years were the corrected Bizarro cartoon last year and
> the addition of the Don Herbert video yesterday.
I cannot believe I overlooked Josh Zyber's fantastic LaserDisc
information archive:
<http://www.mindspring.com/~laserdisc-forever/>
Perhaps we should begin a new thread whose postings contain
URLs to information resources. I just now noticed Josh has a
request for articles here:
<http://www.mindspring.com/~laserdisc-forever/
endcredits.htm#helpwanted>
rjn
> Now you've piqued my curiousity. 633nm is the realm of lasers
> used for DVDs. Is that what IEC-857 addresses?
Full title of IEC-857 is:
Pre-recorded optical reflective videodisk system
"Laser vision" 60 Hz/525 lines-M/NTSC
First edition 1986
It covers most of the physical and logical specifications
of pre-LD LV. It appears to be missing a lot of detail
you'd need to actually master an LV, presumably
covered in the Pioneer "Blue Book", which I don't have.
> The claimed laser wavelength of, for example, a CLD-D704
> and CLD-99, is 780nm, and 670nm for the HLD-X9, so I'm
> puzzled where the 633nm comes into the picture.
633 is the native wavelength of HeNe gas tube lasers.
I just noticed that in IEC 857 Amendment 1 (1991-07),
which I do have, the wavelength was changed to 780nm,
which is CD spec. The also added a magnitude spec
to capture the pit/land signal change.
An interesting question is: what were LDs made to in
terms of pit depth and refraction after CD came in.
Did they keep making them for optimal performance
on 633nm players, or 780nm players, or in between?
> For what it's worth, several rotted LDs that could not be
> played on my CLD-D704 and CLD-99 would play, albeit with
> some video noise, on my HLD-X9, so that suggests the finer
> laser beam (670nm) contributes to that playability.
Try 'em, on yer Pioneer VP-1000 :-)
I suspect "finer" has less to do with it than being a more
precise match for 1/4 lamba interference detection, if, big if,
those marginal LDs were made to 633nm pit depth.
Borked Pseudo Mailed
wrote:
>I haven't checked in a few years to see if Laserland still exists.
Found their URL, they're gone:
"After 15 years, LaserLand Home Theater
closes its doors to the public.
Thank you for your business!"
I think I bought one thing there. As you wrote, their prices were the
absolute highest. There were other things about the place that bothered
me. They were really paranoid about shoplifting, going so far as to hand
purchases over a rail as you existed the store, you weren't allowed to
carry stuff directly out. The final straw for me was when they were doing
a remodel, setting up demo rooms for home theater equipment. The place was
filled with the absolute strongest smell you can imagine of paint and some
other solvent. And while that was going on, the owner or manager of the
store was busy chewing the fat exercising his lips in a really loud and
obnoxious voice, totally clueless on how his behavior and the remodel was
effecting the rest of the store.
I walked out and never returned. Good riddance to them!
cfca...@gmail.com
> In taking another look at IEC-857, the NTSC LV spec, it calls
> for a specific laser frequency (6328A, 633nm), numerical
> aperture (0.40) and index of refraction/thickness envelope.
> It also specifies the cross section and diffraction rings
> of the readout beam, and reflectivity (>70%) of the medium,
> without specifying whether land or pit.
>
> Curiously, other than track pitch (1.4-2um) it says nothing
> about pit geometry (shape, width, depth, or whether incuse
> or relief), nor even the ratio of pit/land reflectivity.
>
> One has to consult other sources to discover that stamped
> and cast LDs are probably using a pit that is 103nm deep
> and 400nm wide.
>
> 103nm is 1/4 wavelength of the 633nm laser light, accounting
> for refraction. If half the light is reflected by the pit,
> and half by the land, the result is signal cancellation
> at pits, and full reflection at lands. The pits appear
> "black" to the detector. Elegant.
>
> Presumably the IEC spec was vague on this to allow for
> totally non-reflective (actually black) pits, which
> could be any depth or size, or no depth at all.
>
> on the 1/4 wavelength reflectivity principle, any
> laser with a materially different wavelength may
> have to have to use some other means of detecting
> pits. If you can play a vinyl LP with a laser, this is
> obviously possible.
>
> How much different can the wavelength be? I don't
> really know. However, after the IEC-857 spec was written,
> LV switched to laser diodes and added CD playback
> (which calls for a 780nm source). So it could be that
> typical LD players are not actually using a 6328A source.
>
> Is using a laser wavelength substantially different
> from 6328A/633nm necessarily beneficial in playback
> of LDs? That's not at all clear to me.
>
> --
> NOT speaking for any employer, client or Internet Service Provider.
There's an additional factor at work here. Although the explanation
normally given for the operation of the optical mechanism is the
interference principle, as you have pointed out, it can't be that
specific. It might have been in the Isailovic reference book that I
encountered a different explanation, which incidentally brings out the
fact that the "pits" can be either raised or depressed (I believe
different mastering & manufacturing processes produced different
results). Essentially, there is a "classical" optical phenomenon
going on : the laser is focussed on a plane defined by the "lands" of
the disc, so when the light spot passes over a pit/bump, instead of
being reflected back to the pickup, the light is diffused & the
intensity received by the photodiode falls off sharply. This helps to
explaine why laser wavelengths substantially different from the HeNe
633 can still give acceptable results, even though interference
phenomena are very sensitive to shifts in wavelength or dimensions
(hence their use for checking surface flatness into the nanometer
range on optical flats, Jo-blocks, & the like). While reproduction
may be optimum at 633 nm where the interference principle dominates, I
shouldn't be surprised if a blue laser actually gave better results
due to the smaller focus spot & thus sharper on-off transitions.
As far as alternative mastering processes and disc structures, in the
early days of the Compact Disc there was a direct-metal-mastering
process which used a stylus to engrave a continuous groove with a V-
shaped bottom. The fluctuating depth of this groove resulted in
greater or less light return to the pickup, & the control of the
stylus was apparently good enough to give sufficiently sharp
transitions for EFM to work. I don't know whether it was good enough
for FM, though, which is substantially less tolerant of jitter.
--publius--
Nico de Vries
The 'read' indeed was a typo for red. The point is that Laserdiscs were
originally designed for read out with a Helium-Neon gas laser, which emits
visible red light. CD's however were designed for read out by an infrared
semiconductor laser, and cannot be read by a red laser, hence all DVD
players have dual wave length laser pickups (or two seperate pickups like
the Pioneer DVL-family) to facilitate reading CD's.
The CLD-1010/1050 rumor it having a red laser is very unlikely, because as
stated before my CLD-1050 does not produce visible red light while playing
an LD. Also, when it would indeed have a red laser for LD playback, why
would would Pioneer go the hard and more expensive way and use a dual
wavelength pick-up (would have been a world first) when an infrared one
would also do the job?
Regards,
Nico de Vries
"Thad Floryan" <th...@thadlabs.com> wrote in message
news:f1253350-d96f-49cb...@i20g2000prf.googlegroups.com...
film11
> Continuing in this vein, my vote is for the HLD-X9. Because of
> its shorter-wavelength red laser diode (670 nm) it could play
> rotted LDs that could not be played on a CLD-704 or CLD-99 whose
> laser wavelengths are 780 nm (IR).
This is one of the X9's greatest strengths. It can play every side of
a severely rotted disc (WILLOW for example), be it CLV or CAV and you
wouldn't know there was anything wrong with the disc!
cfca...@gmail.com
> Hello group,
>
> The 'read' indeed was a typo for red. The point is that Laserdiscs were
> originally designed for read out with a Helium-Neon gas laser, which emits
> visible red light. CD's however were designed for read out by an infrared
> semiconductor laser, and cannot be read by a red laser, hence all DVD
> players have dual wave length laser pickups (or two seperate pickups like
> the Pioneer DVL-family) to facilitate reading CD's.
>
> The CLD-1010/1050 rumor it having a red laser is very unlikely, because as
> stated before my CLD-1050 does not produce visible red light while playing
> an LD. Also, when it would indeed have a red laser for LD playback, why
> would would Pioneer go the hard and more expensive way and use a dual
> wavelength pick-up (would have been a world first) when an infrared one
> would also do the job?
>
> Regards,
>
> Nico de Vries
Early DVD players do not have dual-wavelength pickups, & read CDs just
fine. They cannot, however, read certain recordable CDs (I think the
problem is mostly with CD-RWs), because the dyes used with those discs
do not produce enough contrast in the red wavelengths. Also, I have
seen a Pioneer service diagramme of a LaserDisc player with two
separate pickups, one for LD & the other for CD. I imagine that they
had some difficulty tweaking the optics sufficiently to get a good
"read" off the LD in the beginning -- one of the subsidiary advantages
of the dual-wavelength pickup for CD-DVD players is that it simplifies
some of the optical design problems presented by the different
thickness, track pitch, & other characteristics of the two formats.
--publius--
unclejr
> This is one of the X9's greatest strengths. It can play every side of
> a severely rotted disc (WILLOW for example), be it CLV or CAV and you
> wouldn't know there was anything wrong with the disc!
My LD-S2 has the He-Ne 780 nm laser, and it plays rotters pretty well,
so there must be more to it than the beam width.
-Junior
Thad Floryan
Uh, He-Ne (as in the gas lasers) has a wavelength of 633nm,
shorter than even the laser LED in the HLD-X9 (670nm).
Secondly, the LD-S2 is a (relatively) modern player and has both-side
play which He-Ne LD players never did (or could do).
If anything, the LD-S2 might share some processing circuits
with the HLD-X9 -- I haven't found a service manual for the LD-S2.
unclejr
> Uh, He-Ne (as in the gas lasers) has a wavelength of 633nm,
> shorter than even the laser LED in the HLD-X9 (670nm).
I'll take your word for it. :-)
> Secondly, the LD-S2 is a (relatively) modern player and has both-side
> play which He-Ne LD players never did (or could do).
No. The LD-S2 is a single-side player.
> If anything, the LD-S2 might share some processing circuits
> with the HLD-X9 -- I haven't found a service manual for the LD-S2.
No. From what I've read from and discussed with Kurtis, it's Japanese
cousin is the HLD-X0.
-Junior
nin...@gmail.com
laserdisc player and gives a rather good image on well mastered
discs.
In pure image quality, the HLD-X0 is the best I ever had, and I have
had two HLD-X9 ;)
Nico de Vries
"unclejr" <wat...@kenyon.edu> wrote in message
news:11788f80-44c0-4476...@y33g2000prg.googlegroups.com...
-Junior
Some confusion going on. The Japanese cousin of the Elite LD-S2 is the
LD-X1, which appeared two years earlier. If you need a service manual for
the Elite LD-S2/LD-X1, I have got an incomplete one, although all schematics
are there.
BTW: I am looking for a functional laser pickup for the LD-X1 I have got.
Can any one help me? Kurtis perhaps?
Nico de Vries
ron felder
Dead Link. When I purchased my VP-1000 back in December 1980 Pioneer sent me
the demo disc explain why laser and it had Mr. Wizard on it explain how it
works.
Ron
Thad Floryan
> [...]
> Dead Link. When I purchased my VP-1000 back in December 1980 Pioneer sent me
> the demo disc explain why laser and it had Mr. Wizard on it explain how it
> works.
As I wrote 2 minutes afterwards on March 14, 2009:
> <http://thadlabs.com/LD_info/how_laserdisks_work_Don_Herbert.flv>
Oops; typo. The URL is:
<http://thadlabs.com/LD_info/how_laserdiscs_work_Don_Herbert.flv>
"c" instead of the original "k" in laserdiscs