Welcome to Laser Pointer Forums! If you are looking for a laser you may want to check out the Laser Company Top Sites List. The link will open in a new window for your convenience.

Colorful 2018, Colorful Laser Power Meter
 Laser Pointers TEM00 to TEM01 Mode Hopping 532nm
 User Name Remember Me? Password

LPF Laser Pointer Company Database (link opens new window)

10-04-2014, 05:45 AM #1
 Super Moderator Join Date: Jan 2014 Location: Great White Frozen North Posts: 9,193 Rep Power: 1081900
Super Moderator

Join Date: Jan 2014
Location: Great White Frozen North
Posts: 9,193
Rep Power: 1081900
TEM00 to TEM01 Mode Hopping 532nm

What causes an otherwise TEM00 laser to mode hop to TEM01? I mean, other than temperature changes? I have several of these lasers, identical, only one does this.

Here's a short video showing it:

http://photos.imageevent.com/qdf_fil...0Splitting.mp4

__________________

Attention new brothers of the collimated light!

Newbie advice: Please take the time to first make an introduction in the Welcome section before posting questions.

Divergence to spot size calc: - 1 mRad is about .057 degrees which expands to be very roughly ~10% the diameter of the moon or sun at their distances.

Divergence Calculator: pseudonomen137's JScript mRad Calculator - Measure your lasers beam dia. at 1 foot & then 20'.

Online calc. to determine spot intensity at different mRad's & powers: http://tinyurl.com/divergence-calculator

Laser Power Density Calculator: Laser Power Density Calculator - Ophir

Build a beam expander to reduce divergence: http://tinyurl.com/BeamExpander

University YAG Project The Professor's Homebuilt Lasers Site - YAG Lasers

YAG Power Calc. Laser Peak Power Calculator - Ophir

Angular Size Calculator; use with diode angle of radiation spec. for lens dia. at FL: Angular Size Calculator

RHD's Calc: http://lsrtools.1apps.com/RelativeBr...&useRaleigh=on

High Current Pulse Drivers: https://tinyurl.com/ya7whuk3

10-04-2014, 05:53 AM #2
 Banned Join Date: May 2011 Posts: 1,063 Rep Power: 0
VisibleGreen
Banned

Join Date: May 2011
Posts: 1,063
Rep Power: 0
Re: TEM00 to TEM01 Mode Hopping 532nm

Dis-alignment I believe or damage to the diode

10-04-2014, 06:12 AM #3
 Super Moderator Join Date: Jan 2014 Location: Great White Frozen North Posts: 9,193 Rep Power: 1081900
Super Moderator

Join Date: Jan 2014
Location: Great White Frozen North
Posts: 9,193
Rep Power: 1081900
Re: TEM00 to TEM01 Mode Hopping 532nm

I'm showing it with the lens off on a wall about 12 feet from me. This is the output after expansion through a double concave lens.
__________________

Attention new brothers of the collimated light!

Newbie advice: Please take the time to first make an introduction in the Welcome section before posting questions.

Divergence to spot size calc: - 1 mRad is about .057 degrees which expands to be very roughly ~10% the diameter of the moon or sun at their distances.

Divergence Calculator: pseudonomen137's JScript mRad Calculator - Measure your lasers beam dia. at 1 foot & then 20'.

Online calc. to determine spot intensity at different mRad's & powers: http://tinyurl.com/divergence-calculator

Laser Power Density Calculator: Laser Power Density Calculator - Ophir

Build a beam expander to reduce divergence: http://tinyurl.com/BeamExpander

University YAG Project The Professor's Homebuilt Lasers Site - YAG Lasers

YAG Power Calc. Laser Peak Power Calculator - Ophir

Angular Size Calculator; use with diode angle of radiation spec. for lens dia. at FL: Angular Size Calculator

RHD's Calc: http://lsrtools.1apps.com/RelativeBr...&useRaleigh=on

High Current Pulse Drivers: https://tinyurl.com/ya7whuk3

Last edited by Alaskan; 10-04-2014 at 04:45 PM.

10-07-2014, 08:39 PM #4
 Class 2 Laser Join Date: Jan 2011 Posts: 389 Rep Power: 23302
lazeristasUVISIR
Class 2 Laser

Join Date: Jan 2011
Posts: 389
Rep Power: 23302
Re: TEM00 to TEM01 Mode Hopping 532nm

+
A wrong current of the pumping laser diode. Can you change the current and observe the beam?

Is this a sandwich crystal type laser?
__________________
L is for Lasers, and they are good for me.

10-07-2014, 09:16 PM #5
 Class 3B Laser Join Date: Jul 2012 Location: IN, United States Posts: 2,863 Rep Power: 10397
crazyspaz
Class 3B Laser

Join Date: Jul 2012
Location: IN, United States
Posts: 2,863
Rep Power: 10397
Re: TEM00 to TEM01 Mode Hopping 532nm

crystal temperature mainly as well as pump temperature- only if said pump temperature shifts the output by x amount of nm.

Last edited by crazyspaz; 10-07-2014 at 09:16 PM.

12-04-2014, 04:30 AM #6
 Super Moderator Join Date: Jan 2014 Location: Great White Frozen North Posts: 9,193 Rep Power: 1081900
Super Moderator

Join Date: Jan 2014
Location: Great White Frozen North
Posts: 9,193
Rep Power: 1081900
Re: TEM00 to TEM01 Mode Hopping 532nm

Thanks everyone, late to see the responses.
__________________

Attention new brothers of the collimated light!

Newbie advice: Please take the time to first make an introduction in the Welcome section before posting questions.

Divergence to spot size calc: - 1 mRad is about .057 degrees which expands to be very roughly ~10% the diameter of the moon or sun at their distances.

Divergence Calculator: pseudonomen137's JScript mRad Calculator - Measure your lasers beam dia. at 1 foot & then 20'.

Online calc. to determine spot intensity at different mRad's & powers: http://tinyurl.com/divergence-calculator

Laser Power Density Calculator: Laser Power Density Calculator - Ophir

Build a beam expander to reduce divergence: http://tinyurl.com/BeamExpander

University YAG Project The Professor's Homebuilt Lasers Site - YAG Lasers

YAG Power Calc. Laser Peak Power Calculator - Ophir

Angular Size Calculator; use with diode angle of radiation spec. for lens dia. at FL: Angular Size Calculator

RHD's Calc: http://lsrtools.1apps.com/RelativeBr...&useRaleigh=on

High Current Pulse Drivers: https://tinyurl.com/ya7whuk3

12-08-2014, 04:01 AM #7
 Class 2M Laser Join Date: Sep 2007 Location: United States Posts: 634 Rep Power: 30
o_DEATH_ANG3L_o
Class 2M Laser

Join Date: Sep 2007
Location: United States
Posts: 634
Rep Power: 30
Re: TEM00 to TEM01 Mode Hopping 532nm

Do you have an oscilloscope?

12-08-2014, 04:06 AM #8
 Super Moderator Join Date: Jan 2014 Location: Great White Frozen North Posts: 9,193 Rep Power: 1081900
Super Moderator

Join Date: Jan 2014
Location: Great White Frozen North
Posts: 9,193
Rep Power: 1081900
Re: TEM00 to TEM01 Mode Hopping 532nm

Yep, 100 MHz.
__________________

Attention new brothers of the collimated light!

Newbie advice: Please take the time to first make an introduction in the Welcome section before posting questions.

Divergence to spot size calc: - 1 mRad is about .057 degrees which expands to be very roughly ~10% the diameter of the moon or sun at their distances.

Divergence Calculator: pseudonomen137's JScript mRad Calculator - Measure your lasers beam dia. at 1 foot & then 20'.

Online calc. to determine spot intensity at different mRad's & powers: http://tinyurl.com/divergence-calculator

Laser Power Density Calculator: Laser Power Density Calculator - Ophir

Build a beam expander to reduce divergence: http://tinyurl.com/BeamExpander

University YAG Project The Professor's Homebuilt Lasers Site - YAG Lasers

YAG Power Calc. Laser Peak Power Calculator - Ophir

Angular Size Calculator; use with diode angle of radiation spec. for lens dia. at FL: Angular Size Calculator

RHD's Calc: http://lsrtools.1apps.com/RelativeBr...&useRaleigh=on

High Current Pulse Drivers: https://tinyurl.com/ya7whuk3

12-08-2014, 04:16 AM #9
 Class 2M Laser Join Date: Sep 2007 Location: United States Posts: 634 Rep Power: 30
o_DEATH_ANG3L_o
Class 2M Laser

Join Date: Sep 2007
Location: United States
Posts: 634
Rep Power: 30
Re: TEM00 to TEM01 Mode Hopping 532nm

I was going to suggest connecting your driver to your scope and see what you get whilst adjusting the current. Some factors that can affect whether or not mode hopping occurs are laser case temperature, injection current and optical feedback. Reflections of the laser beam back into the laser cavity should be avoided. Slight canting of any partially or completely reflective surface will help eliminate feedback.

12-08-2014, 04:28 AM #10
 Super Moderator Join Date: Jan 2014 Location: Great White Frozen North Posts: 9,193 Rep Power: 1081900
Super Moderator

Join Date: Jan 2014
Location: Great White Frozen North
Posts: 9,193
Rep Power: 1081900
Re: TEM00 to TEM01 Mode Hopping 532nm

Thanks, I've noticed temperature does impact whether this happens or not quite a bit for most of my cheap lasers which do this, but this one particular laser seems to be stably unstable regardless. I find it an interesting effect.
__________________

Attention new brothers of the collimated light!

Newbie advice: Please take the time to first make an introduction in the Welcome section before posting questions.

Divergence to spot size calc: - 1 mRad is about .057 degrees which expands to be very roughly ~10% the diameter of the moon or sun at their distances.

Divergence Calculator: pseudonomen137's JScript mRad Calculator - Measure your lasers beam dia. at 1 foot & then 20'.

Online calc. to determine spot intensity at different mRad's & powers: http://tinyurl.com/divergence-calculator

Laser Power Density Calculator: Laser Power Density Calculator - Ophir

Build a beam expander to reduce divergence: http://tinyurl.com/BeamExpander

University YAG Project The Professor's Homebuilt Lasers Site - YAG Lasers

YAG Power Calc. Laser Peak Power Calculator - Ophir

Angular Size Calculator; use with diode angle of radiation spec. for lens dia. at FL: Angular Size Calculator

RHD's Calc: http://lsrtools.1apps.com/RelativeBr...&useRaleigh=on

High Current Pulse Drivers: https://tinyurl.com/ya7whuk3

12-08-2014, 04:32 AM #11
 Class 2M Laser Join Date: Sep 2007 Location: United States Posts: 634 Rep Power: 30
o_DEATH_ANG3L_o
Class 2M Laser

Join Date: Sep 2007
Location: United States
Posts: 634
Rep Power: 30
Re: TEM00 to TEM01 Mode Hopping 532nm

Do you happen to have a small TEC module handy? If you don't then I would pick some up. these little things are amazing. If you do then cool that diode down. Run 12v through the TEC and see if your laser still goes TEM01. If it does, blame the optics lol.

12-08-2014, 05:04 AM #12
 Super Moderator Join Date: Jan 2014 Location: Great White Frozen North Posts: 9,193 Rep Power: 1081900
Super Moderator

Join Date: Jan 2014
Location: Great White Frozen North
Posts: 9,193
Rep Power: 1081900
Re: TEM00 to TEM01 Mode Hopping 532nm

Do I have TEC's? LOL... man, I have a bunch of them, like 50+ of them of many sizes. Thanks, might be easier just to spray the body of the host with some component cooling spray, as long as I don't cause it to get too cold and condensation becomes a problem. Even easier, I can set it outside for a few minutes, it's getting chilly here now.
__________________

Attention new brothers of the collimated light!

Newbie advice: Please take the time to first make an introduction in the Welcome section before posting questions.

Divergence to spot size calc: - 1 mRad is about .057 degrees which expands to be very roughly ~10% the diameter of the moon or sun at their distances.

Divergence Calculator: pseudonomen137's JScript mRad Calculator - Measure your lasers beam dia. at 1 foot & then 20'.

Online calc. to determine spot intensity at different mRad's & powers: http://tinyurl.com/divergence-calculator

Laser Power Density Calculator: Laser Power Density Calculator - Ophir

Build a beam expander to reduce divergence: http://tinyurl.com/BeamExpander

University YAG Project The Professor's Homebuilt Lasers Site - YAG Lasers

YAG Power Calc. Laser Peak Power Calculator - Ophir

Angular Size Calculator; use with diode angle of radiation spec. for lens dia. at FL: Angular Size Calculator

RHD's Calc: http://lsrtools.1apps.com/RelativeBr...&useRaleigh=on

High Current Pulse Drivers: https://tinyurl.com/ya7whuk3

Last edited by Alaskan; 12-08-2014 at 05:32 AM.

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

All times are GMT. The time now is 09:27 PM.

 -- DarkShadows V5 -- Responsive LPF -2562016 -- Default Style Contact Us - Laser Pointers - Archive - Top