red laser diode multimode

[harryd]

hello everyone,
can someone help me and tell me is the red laser diode in the laser pointer a multimode or a single mode? the wavelength is around 632nm and i am actually trying to figure out whether to use a multimode or a single mode.

 

[kevinmassey]

Yes, if you post a picture. Also it's probably 650nm, or possibly 635nm.

 

[harryd]

well i cant post a picture but it is the typical red laser pointer the key chain laser pointers.

another thing, i am doing an experiment to measure the intensity distribution of the beam by scanning an optical fiber across the beam. should i use a single mode fiber or a multi mode as a trade off between intensity and resolution.

thanks a lot for answering

 

[harryd]

how do i know from a picture?

 

[kevinmassey]

this is a multimode red. http://laserpointerforums.com/f49/more-help-collimating-multi-mode-red-diode-43172.html

 

[harryd]

and how does a single mode look like?

 

[lasersbee]

A 5mW Dollar Store keychain laser is single mode...
it produces a single oval to round dot... unlike the
the MULTI bar output od a MULTImode LD..

Jerry

 

[harryd]

THANK YOU!!

that brings me to the next question. should i use a single mode fiber or a multi mode fiber( as a trade off of resolution and intensity) in an experiment where i scan an optical fiber across the laser beam to measure the intensity distribution ?... and what happens if i propagate the single mode beam in a multi mode fiber in terms of the intermodal dispersion?

excuse my lack of information in the field but i am trying to connect the dots.

thanks again all of you, specially jerry.