Old 03-08-2010, 10:56 PM #1
bootleg2go's Avatar
Class 2M Laser
 
Join Date: Nov 2006
Posts: 656
Rep Power: 1748
bootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond repute
bootleg2go bootleg2go is offline
Class 2M Laser
bootleg2go's Avatar
 
Join Date: Nov 2006
Posts: 656
Rep Power: 1748
bootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond reputebootleg2go has a reputation beyond repute
Default Misconceptions about diode "lifetime" ratings

It seems that there are some misconceptions/ misunderstandings about laser diode lifetime ie. MTTF/MTBF ratings.
I saw a post in another thread earlier today where people were discussing this, but it wasn't the thread topic and I cannot find the thread now.

Anyway, someone had thought that since their laser or the diode in their laser was rated for 5000 or 8000 hours that it meant that the laser/diode would work for that amount of time; this is not so. Many may in fact last up to or perhaps even longer than the rated, but many will not even last a fraction of that amount of time. MTBF/MTTF numbers are a statistic that are good for determining product quality when many thousands or millions of units are considered, but they mean very little to how long an individual unit will live. For the person buying laser the number can be used for instance to compare the quality of one diode to another in that a diode with a 8000hr MTBF on average will be of higher quality than one of 5000hr MTBF; but it doesn't mean much more.

Here's a link that describes this somewhat and there's more on the web, just do a google search.
Using MTBF and Time Dependent Reliability for disks : Ramblings from Richard's Ranch
One of the interesting things that is used to describe MTBF is that in the USA, the death rate of children between the ages of 5 to 14 is 0.0208% per year, this would equal an MTBF of 4,807 years for these kids.
This article was written about MTBF in disk drives, but it applies to all electronics or anything that uses MTBF as a quality metric.


bootleg2go is offline   Reply With Quote


















Old 03-08-2010, 11:38 PM #2
lasersbee's Avatar
Class 4 Laser
 
Join Date: Sep 2008
Location: Quebec, Canada
Posts: 16,823
Rep Power: 960027
lasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond repute
lasersbee lasersbee is offline
Class 4 Laser
lasersbee's Avatar
 
Join Date: Sep 2008
Location: Quebec, Canada
Posts: 16,823
Rep Power: 960027
lasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond repute
Default Re: Misconceptions about diode "lifetime" ratings

I believe this is the Thread you are referring to...
I may be wrong...

http://laserpointerforums.com/f45/o-...why-48848.html


Jerry
__________________

J.BAUER Electronics Home Page

LaserBee Laser Power Meter Products meet your needs
at affordable Prices:
See them all here on LPF

LaserBee Power Meter products ALWAYS in Stock
and ready to ship

Also available on eBay:Check availability here..

Subsidary: Pharma Electronic Solutions


This banner is available to and can be copied/used FREE by any LaserBee owner
lasersbee is offline   Reply With Quote
Old 03-08-2010, 11:42 PM #3
Class 3B Laser
 
Join Date: Oct 2009
Location: Central New York State - Watkins Glen - planet Earth
Posts: 2,745
Rep Power: 102
photonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond repute
photonaholic photonaholic is offline
Class 3B Laser
 
Join Date: Oct 2009
Location: Central New York State - Watkins Glen - planet Earth
Posts: 2,745
Rep Power: 102
photonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond reputephotonaholic has a reputation beyond repute
Default Re: Misconceptions about diode "lifetime" ratings

Right on the head Jerry, sounds like he's describing our conversation on that thread.....
__________________
Thanks for reading my post.
Kind regards, Wayne

------------------------------------------------------------------
"Disclaimer: all posts made by me are based on my own opinion only,
That opinion is subject to change without notice."


Too much knowledge is dangerous, not enough is worse.
Adapted from Einstein quote.
------------------------------------------------------------------
If you want to burn things, buy a lighter
------------------------------------------------------------------
My Pet Forums - for the animal fans Link
Dances With Reptiles - If you like snakes Link
photonaholic is offline   Reply With Quote
Old 03-08-2010, 11:58 PM #4
brando132's Avatar
is beyond cool
 
Join Date: Jan 2010
Location: Saskatchewan, Canada
Posts: 578
Rep Power: 15
brando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of light
brando132 brando132 is offline
is beyond cool
brando132's Avatar
 
Join Date: Jan 2010
Location: Saskatchewan, Canada
Posts: 578
Rep Power: 15
brando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of light
Default Re: Misconceptions about diode "lifetime" ratings

Quote:
Originally Posted by photonaholic View Post
Right on the head Jerry, sounds like he's describing our conversation on that thread.....
Looked more like an argument to me.
__________________

~3.5W 465nm Jetlaser PL-E Pro
527mW 532nm Rayfoss FMK
305mW 532nm labby.
~35mW 532nm DX Gunsight

13.6mW 632.8nm 14" HeNe bare tube.
~100mW 655nm DX NewWish Pen
--------------------------------
488 Rep Points.
brando132 is offline   Reply With Quote
Old 03-09-2010, 12:10 AM #5
RA_pierce's Avatar
Class 3B Laser
 
Join Date: Sep 2007
Location: Southern California
Posts: 3,310
Rep Power: 176945
RA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond repute
RA_pierce RA_pierce is online now
Class 3B Laser
RA_pierce's Avatar
 
Join Date: Sep 2007
Location: Southern California
Posts: 3,310
Rep Power: 176945
RA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond reputeRA_pierce has a reputation beyond repute
Default Re: Misconceptions about diode "lifetime" ratings

The way I always understood it was this:

MTTF: Mean Time To Failure
The average time it takes for a piece of hardware to fail out of X number of tested items.

MTBF: Mean Time Between Failures
The average time a piece of hardware will operate between failures and repair.

I never thought of the MTTF as a guarantee of how long a laser diode would "live," but rather an estimate of how long I can expect a laser diode to live on average.
Obviously, in order to get an average figure, you will have some on the high end and some on the low end, with most in the middle range. Variations in production will cause this.
A component with a higher MTTF rating can usually be considered "higher quality" but by no means does it guarantee that an individual item will last longer than an a product with a lower MTTF.

I'm not sure I understand what the 5-14 year old children example has to do with this and where the 5000 year MTBF for a human being came from.
How was that calculated?
__________________
495nm details
508nm details
638nm details
How to build a pen
RA_pierce is online now   Reply With Quote
Old 03-09-2010, 12:51 AM #6
lasersbee's Avatar
Class 4 Laser
 
Join Date: Sep 2008
Location: Quebec, Canada
Posts: 16,823
Rep Power: 960027
lasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond repute
lasersbee lasersbee is offline
Class 4 Laser
lasersbee's Avatar
 
Join Date: Sep 2008
Location: Quebec, Canada
Posts: 16,823
Rep Power: 960027
lasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond reputelasersbee has a reputation beyond repute
Default Re: Misconceptions about diode "lifetime" ratings

Quote:
Originally Posted by brando132 View Post
Looked more like an argument to me.
Not to me.....

Jerry
__________________

J.BAUER Electronics Home Page

LaserBee Laser Power Meter Products meet your needs
at affordable Prices:
See them all here on LPF

LaserBee Power Meter products ALWAYS in Stock
and ready to ship

Also available on eBay:Check availability here..

Subsidary: Pharma Electronic Solutions


This banner is available to and can be copied/used FREE by any LaserBee owner
lasersbee is offline   Reply With Quote
Old 03-09-2010, 01:03 AM #7
brando132's Avatar
is beyond cool
 
Join Date: Jan 2010
Location: Saskatchewan, Canada
Posts: 578
Rep Power: 15
brando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of light
brando132 brando132 is offline
is beyond cool
brando132's Avatar
 
Join Date: Jan 2010
Location: Saskatchewan, Canada
Posts: 578
Rep Power: 15
brando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of lightbrando132 is a glorious beacon of light
Default Re: Misconceptions about diode "lifetime" ratings

Well, you were a participant so you don't "count".
__________________

~3.5W 465nm Jetlaser PL-E Pro
527mW 532nm Rayfoss FMK
305mW 532nm labby.
~35mW 532nm DX Gunsight

13.6mW 632.8nm 14" HeNe bare tube.
~100mW 655nm DX NewWish Pen
--------------------------------
488 Rep Points.

Last edited by brando132; 03-09-2010 at 02:31 AM.
brando132 is offline   Reply With Quote
Old 03-09-2010, 01:16 AM #8
Class 4 Laser
 
Join Date: Nov 2008
Posts: 5,728
Rep Power: 3030
ElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond repute
ElektroFreak ElektroFreak is offline
Class 4 Laser
 
Join Date: Nov 2008
Posts: 5,728
Rep Power: 3030
ElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond reputeElektroFreak has a reputation beyond repute
Default Re: Misconceptions about diode "lifetime" ratings

Quote:
Originally Posted by bootleg2go View Post
It seems that there are some misconceptions/ misunderstandings about laser diode lifetime ie. MTTF/MTBF ratings.
I saw a post in another thread earlier today where people were discussing this, but it wasn't the thread topic and I cannot find the thread now.

Anyway, someone had thought that since their laser or the diode in their laser was rated for 5000 or 8000 hours that it meant that the laser/diode would work for that amount of time; this is not so. Many may in fact last up to or perhaps even longer than the rated, but many will not even last a fraction of that amount of time. MTBF/MTTF numbers are a statistic that are good for determining product quality when many thousands or millions of units are considered, but they mean very little to how long an individual unit will live. For the person buying laser the number can be used for instance to compare the quality of one diode to another in that a diode with a 8000hr MTBF on average will be of higher quality than one of 5000hr MTBF; but it doesn't mean much more.

Here's a link that describes this somewhat and there's more on the web, just do a google search.
Using MTBF and Time Dependent Reliability for disks : Ramblings from Richard's Ranch
One of the interesting things that is used to describe MTBF is that in the USA, the death rate of children between the ages of 5 to 14 is 0.0208% per year, this would equal an MTBF of 4,807 years for these kids.
This article was written about MTBF in disk drives, but it applies to all electronics or anything that uses MTBF as a quality metric.
This is very true. Fortunately most last quite awhile.. I'll even go so far as to add that when we push diodes like we do regularly here on LPF, that already shaky MTTF figure goes out the window into the realm of almost complete unpredictability when placed against a time line. The vast majority of diodes we see being overdriven will last for awhile, but nowhere near 5,000 or more hours.
__________________
Laser Resources (for n00bs and veterans alike!)

Sam's Laser FAQ (The Laser Bible)

http://www.repairfaq.org/sam/laserfaq.htm

RP Photonics Encyclopedia of Laser Physics and Technology

http://www.rp-photonics.com/encyclopedia.html

ULTIMATE DIY PROJECTOR REFERENCE

http://nqlasers.com/scannerreference...itle=Main_Page

SUCCESS is the best revenge.
ElektroFreak is offline   Reply With Quote
Reply





Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

























Privacy Policy | Advertising Disclaimer | Terms of Use


 


All times are GMT. The time now is 09:10 AM.


Powered by: vBulletin
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO
Privacy Policy | Advertising Disclaimer | Terms of Use
Copyright (C) 2017 Laser Pointer Forums, LLC