Laser pointer discussion. Read/write reviews of laser pointers and laser pointer companies. Learn about all types of laser pointers and lasers





Welcome to Laser Pointer Forums! If you are looking for a laser pointer or want to compare different laser pointer companies, you may want to check out the LPF Laser Pointer Company Database. The link will open in a new window for your convenience.








Green Laser Pointers by Category Blue Laser Pointers by Category Red Laser Pointers by Category
Yellow Laser Pointers by Category Violet Laser Pointers by Category Orange Laser Pointers by Category
Top Laser Pointers by Power - 1 Watt+ Top Laser Pointers by Power - 500mW+ Top Laser Pointers by Power - 250mW+
Laser Pointer Database High Power Laser Pointers Laser Pointer Diodes
Laser Technology Laser Pointer Parts Lasers by Wavelength
Top 10 Laser Pointer Companies Laser Pointer Company Database Visible Beam Laser Pointers


One laser store meets all your needs

























Go Back   Laser Pointer Forums - Discuss Laser Pointers > Lasers > Optics



LPF List of Laser Pointer Companies (link opens new window)



Reply
 
LinkBack Thread Tools Display Modes
Old 12-24-2013, 01:42 AM #1
Junior Member
 
Join Date: Dec 2013
Posts: 3
Rep Power: 0
jwdwh is on a distinguished road
jwdwh jwdwh is offline
Junior Member
 
Join Date: Dec 2013
Posts: 3
Rep Power: 0
jwdwh is on a distinguished road
Default The fluctuating intensity at the exit end of the fiber!

Hi gang,I decide to focuse laser into the SMF ( single mode fiber ),but found that the following system would produce a fluctuating intensity at the exit end of the fiber(Fig 1):

Helium-Neon laser (633 nm, 35 mW, DA(Divergence Angle)=0.66mrad, BD(Beam diameter)=1.23mm) --> lens(20X)--> single mode FC fiber (NA=0.14, 125 micron cladding, 3.6m length)-->power meter. The lens and SMF are all fixed on two separate 5-dimensional positioner(from Newport: http://search.newport.com/?q=*&x2=sku&q2=LP-05A) And all the system are fixed on the optical table.

Here is the problem:
The intensity reaching the power meter is about 26mW with fluctuations as large as 1mW with a frequency of 0.5-1Hz. Since the He-Ne laser has been on for hours and is rather stable at the time of measurement (as measured directly at the laser output), this fluctuation could be caused by the fiber coupling system described above? It is strange that when I vibrate the floor, the intensity doesn’t seem to change much. I suspect it is cause by mechanical deformation of the 5-dimensional positioned, while placed the whole system over a night, the fluctuations is still there. Furthermore, the intensity seems swing with the central point——26mW, and the swing trend seems no rules to follow——sometimes larger than 1mW, sometimes smaller than 0.5mW.
Since the laser is used for scientific experiments, this kind of fluctuating is unbearable. I am curious to know where the disturbance come from and how to eliminate it.

Thanks in advance!
The fluctuating intensity at the exit end of the fiber!-message.png



Last edited by jwdwh; 12-24-2013 at 06:48 AM.
jwdwh is offline   Reply With Quote







LPF List of Laser Pointer Companies (link opens new window)







Old 12-24-2013, 03:16 AM #2
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,144
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,144
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: The fluctuating intensity at the exit end of the fiber!

What power meter are you using? Is this noise in the beam still present between the laser and the lens?
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 12-24-2013, 07:28 AM #3
Junior Member
 
Join Date: Dec 2013
Posts: 3
Rep Power: 0
jwdwh is on a distinguished road
jwdwh jwdwh is offline
Junior Member
 
Join Date: Dec 2013
Posts: 3
Rep Power: 0
jwdwh is on a distinguished road
Default Re: The fluctuating intensity at the exit end of the fiber!

Thanks for reply!
The power meter is a cheap one made in China. While measure directly at the laser output, the reading is quite stable.
I have noticed the "beam" now, so I remove it and retest the output from the fiber, while it seems nothing change, the fluctuating is still there.
jwdwh is offline   Reply With Quote
Old 12-24-2013, 10:01 PM #4
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,144
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,144
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: The fluctuating intensity at the exit end of the fiber!

I don't see how a fiber would cause this. Sounds like something else in the environment is interfering with the sensor.
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 12-26-2013, 03:01 PM #5
BShanahan14rulz's Avatar
Class 3B Laser
 
Join Date: Dec 2009
Posts: 3,175
Rep Power: 264
BShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond repute
BShanahan14rulz BShanahan14rulz is offline
Class 3B Laser
BShanahan14rulz's Avatar
 
Join Date: Dec 2009
Posts: 3,175
Rep Power: 264
BShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond reputeBShanahan14rulz has a reputation beyond repute
Default Re: The fluctuating intensity at the exit end of the fiber!

The fiber is mounted when taking a measurement from it, or is held in the hand in front of power meter? Probably the former, based on your pictures, and no offense meant, just to be clear. I wonder if even in a mount, a broken fiber might fluctuate transmission in that manner?
BShanahan14rulz is offline   Reply With Quote
Old 12-27-2013, 02:27 PM #6
Junior Member
 
Join Date: Dec 2013
Posts: 3
Rep Power: 0
jwdwh is on a distinguished road
jwdwh jwdwh is offline
Junior Member
 
Join Date: Dec 2013
Posts: 3
Rep Power: 0
jwdwh is on a distinguished road
Default Re: The fluctuating intensity at the exit end of the fiber!

Quote:
Originally Posted by BShanahan14rulz View Post
The fiber is mounted when taking a measurement from it, or is held in the hand in front of power meter? Probably the former, based on your pictures, and no offense meant, just to be clear. I wonder if even in a mount, a broken fiber might fluctuate transmission in that manner?
Yes, the fiber is well mounted by a holder when taking measurement. I don't think the fluctuation is cause by a broken fiber.The fiber was bought several days ago and well protected when operated. Even if it is broken,the intensity reaching the power meter may decrease but should be stable. I can't figure out why it will fluctuate such random.
Anyway, thanks for your reply!
jwdwh is offline   Reply With Quote
Old 12-30-2013, 08:30 PM #7
WizardG's Avatar
Class 2 Laser
 
Join Date: May 2011
Location: Oregon
Posts: 398
Rep Power: 2630
WizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond repute
WizardG WizardG is offline
Class 2 Laser
WizardG's Avatar
 
Join Date: May 2011
Location: Oregon
Posts: 398
Rep Power: 2630
WizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond reputeWizardG has a reputation beyond repute
Default Re: The fluctuating intensity at the exit end of the fiber!

Try taking a measurement of the laser itself using a beam expander so the beam isn't just making a dot on the LPM sensor. If that is stable then try a different fiber. My $0.02
__________________
125mW 405
1.157 watt 447
2 meter long hene @ 57mW
Assorted greenies, best @ 244mW of 520
WizardG is offline   Reply With Quote
Reply

Tags
fluctuating intensity smf





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











Loading








Green Laser Pointers by Category Blue Laser Pointers by Category Red Laser Pointers by Category
Yellow Laser Pointers by Category Violet Laser Pointers by Category Orange Laser Pointers by Category
Top Laser Pointers by Power - 1 Watt+ Top Laser Pointers by Power - 500mW+ Top Laser Pointers by Power - 250mW+
Laser Pointer Database High Power Laser Pointers Laser Pointer Diodes






Privacy Policy | Advertising Disclaimer | Terms of Use


 


All times are GMT. The time now is 03:46 AM.


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