Disadvantages of lasers over LEDs?

[Michael A. Terrell]

How did you manage to introduce html formatting using Gecko/Netscape 7.2 ?

Tools: Account settings: Composition & Addressing: check the box for
"Compose messages in HTML format".


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Bob Myers]

Lasers and LEDs are two different things. There is no such thing as a
"laser LED"


Diode lasers

Oh, the irony of it all....

Bob M.

 

[Bob Myers]

Beware. Radium is a clueless nut who likes to talk 'scientific stuff' without
any understanding of the technology.

Gee, ya think?

Bob M.

 

[John de Stigter]

Lasers and LEDs are two different things. There is no such thing as a
"laser LED"

The above statement is just plain embarrassing. You really should do some
reading.

Regards,
John.

 

[[email protected]]

Photonics and telecommunications

Well you should have known better than to post to a moron group
like sci.physics. for teleecommuntions. The only thing
the idiots do in EPA Gore Webmasters.

The disavantage of lasers in telecpommuntions is that
only thing they transposrt is quantum mechanics
fiber non-sense.

The disadavatages of LEDs in photonics is that the only
thing they transport is radio shack.

 

[Don Klipstein]

lasers don't come in white.
also cost more

Well, there is a bit of an exception to that part of lasers not coming
in white...

There are a few multiple wavelength gas lasers around - most notably
multiwavelength argon-krypton ion lasers:

http://repairfaq.cis.upenn.edu/sam/laserarg.htm#argwse

(Within the argon and argon-krypton ion laser section of Sam
Goldwasser's Laser FAQ.)

- Don Klipstein ([email protected])

 

[Phil Hobbs]

The above statement is just plain embarrassing. You really should do some
reading.

Regards,
John.

I've never heard any trained optics person use the therm "laser LED".
Do you have a reference?

Cheers,

Phil Hobbs

 

[[email protected]]

John de Stigter wrote:

I've never heard any trained optics person use the therm "laser LED".
Do you have a reference?

You probably won't, but the term is still in use.

Google on "laser LED" and you will get over a million hits.

 

[Sam Goldwasser]

You probably won't, but the term is still in use.

Google on "laser LED" and you will get over a million hits.

Look closer at those million hits and it will be very hard to find
anything actually called a "laser led" that isn't (1) a tradename
or use of the term in marketing with no basis in the devices used, (2)
actually laser/led because apparently Google doesn't distinguish
between " " and "/" even when in quotes, or (3) a keyword list.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

 

[[email protected]]

[email protected] writes:

Look closer at those million hits and it will be very hard to find
anything actually called a "laser led" that isn't (1) a tradename
or use of the term in marketing with no basis in the devices used, (2)
actually laser/led because apparently Google doesn't distinguish
between " " and "/" even when in quotes, or (3) a keyword list.

I did notice the above.

I also noticed that most of the sites using the term "laser LED" to
mean a laser diode seemed to be in the UK or places with a heavy UK
influence.

OTOH, do you think "radium" is trained in anything, much less optics?

 

[Fleetie]

OTOH, do you think "radium" is trained in anything, much less optics?

Yeah, I expect he is probably potty-trained.


Martin

 

[Michael A. Terrell]

Yeah, I expect he is probably potty-trained.

Martin

Would you bet your nice, clean carpet on it?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Don Klipstein]

You probably won't, but the term is still in use.

Google on "laser LED" and you will get over a million hits.

I tried exact phrase of "laser LED" on Google and the hit count did
indeed slightly exceed a million.

However, this did include items where the actual content was
"laser/LED", "LASER LED" and the like, along with lack of case
sensitivity and including all documents having "laser" and "LED" in any
keyword "hit list" should they have "LED" first word after "laser".

Among the top 10 hits:

10th had a device having both a laser diode and LEDs as separate
light-emitting devices.

http://www.physlink.com/estore/cart/LaserLEDSniper.cfm

9th has some occurrences of the phrase "laser/LED" but only when
reasonably applicable to something that is one or the other but not
necessarily both.

http://www.us.tuv.com/product_testing/laser_led_devices/index.html

8th is mentioned by Google to be having to do with laser/LED printers!
Every single one of the many occurrences of the word "laser" that I found
there was not immediately followed by the word "LED" except in a line that
appears to me to be at least somewhat of a title.

http://reviews-zdnet.com.com/4566-3159_16-0.html

7th place has many ocurrences of the phrase "laser LEDs" and "laser LED"
but what they talk about surely appears to me to be more-ordinary
non-laser LEDs.

http://www.dvhardware.net/modules.php?name=Reviews&rop=showcontent&id=23

6th place appeared to me to be some hypester trying to sell LEDs or LED
lighting devices of some sort, and having "lazer LED" occurring more than
"laser LED".

http://www.xoxide.com/lazerled.html

5th place hit - I looked within and found every single occurrence of
the word "laser" to not be immediately followed by the word "LED".

http://www.sciencewatch.com/jan-feb2000/sw_jan-feb2000_page3.htm

4th place hit has "laser LED" having high occurrence where usage has
been considered by most to be atypical for at least 10 years and probably
at least 15-20.

http://www.bigbruin.com/reviews/wisetechleds/

3rd place hit does so by having in it "LASER/LED" immediately preceding
"power output monitor" with implication that lasers and LEDs are two
different items that this 3rd place hit page is good for due to some
similarity. I surely find this schematic as good for completely non-laser
LEDs as it is good for laser diodes of similar wavelength.

http://www.discovercircuits.com/PDF-FILES/laserpwr.pdf

2nd place hit is:
http://www.sunbeamtech.com/PRODUCTS/LASER LED.HTML

With the phrase "LASER LED" occurring with the "laser" part of that
appearing to me to be nonsense.

1st place hit is a page by a supplier of laser diodes, and I currently
find in that page every single occurrence of the word "laser" to not be
immediately followed by the word "LED".

http://www.roithner-laser.com/LP-laserdiodesIR.htm

- Don Klipstein ([email protected])

 

[PD]

Hi:

What are the disadvantages of lasers when compared to LEDs?

Lasers are
a) bigger
b) more expensive
c) monochromatic
d) sometimes require safety training, depending on their frequency
e) have lower lifetimes, on average

Of course, no one has written a science fiction story involving a LED
gun, so the laser might win, anyway, depending on how important the
"cool!" factor is to you.

PD

 

[Bob Myers]

I tried exact phrase of "laser LED" on Google and the hit count did
indeed slightly exceed a million.

And whether or not the term is in common use -

1. "LED" stands for Light-Emitting Diode, right?

2. A "laser diode" IS a diode, and it emits light. Granted it
is not what most people mean when they say "LED" (and
"non-coherent light-emitting diode" isn't all that likely to
catch on...), but....

QED. We can now all go back to more important things,
such as our afternoon naps.

Bob M.

 

[Kai-Martin]

Lasers are
a) bigger

By far the biggest part of both devices is the package. The actual laser
diode is hard to spot on arms length.

b) more expensive

Generally true, but there are exceptions.

c) monochromatic

For most applications this is an advantage.

d) sometimes require safety training, depending on their frequency

.... and depending on their power. They operate at power levels way beyond
the capability of LEDs.

e) have lower lifetimes, on average

True. Still, the lifetime of red and IR Laser diodes is a few 100.000 hours.
Compare this to the average lifetime of a car.

f) need more sophisticated drivers.

g) are more sensitive to EMV damage.

h) sometimes show erratic jumps in frequency and power.

i) laser iluminated objects show speckles.

Of course, no one has written a science fiction story involving a LED
gun, so the laser might win, anyway, depending on how important the
"cool!" factor is to you.

It is difficult to get a fairly collimated beam from a LED. Even with
expensive optics it is impossible to achieve collimation comparable to a
cheap laser pointers.

---<(kaimartin)>---

 

[John de Stigter]

I've never heard any trained optics person use the therm "laser LED".
Do you have a reference?

Cheers,

Phil Hobbs

For a full explanation see Bob Myer's reply elsewhere, However:
1. A LED is a diode - a light emitting diode.
2. A Laser Diode is a diode, and is now probably the most common form of
laser ( but not the only ) due to the huge numbers of cd and dvd players in
existence.
To say that "Lasers and LEDs are two different things" is an insult to the
PN junction.

Regards,
John

 

[Tim Williams]

To say that "Lasers and LEDs are two different things" is an insult to the
PN junction.

And, AFAIK, below the lasing threshold, a laser diode is an LED. Only when
enough photons are present to stimulate further emission does it become a
laser.

Tim

 

[Jimbo]

Radium, I assume you are talking about fiber optic applications.

LED based systems have a much lower bandwidth but are usually cheaper.
LEDs are usually used in multi-mode systems while lasers are generally
used in single-mode systems. Also, LED systems do not multiplex well
for many reasons. If you want to have many optical channels a laser
may be the way to go. I think the current ITU standard calls for 128
wavelength based channels. I would google "WDM" "DWDM" and "UDWDM"
to get an overview on the way fiber optics systems are mutliplexed. If
you want a more detailed technical analysis just email me. Fiber
optics is a vast subject.