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 Laser Pointer Forums - Discuss Laser Pointers TEM00 to TEM01 Mode Hopping 532nm Laser Pointer Company Database     Laser Top Sites List     Lasers by Type     Green Lasers

10-04-2014, 04:45 AM #1
 Class 3B Laser Join Date: Jan 2014 Location: Near Mosul, Iraq Posts: 4,249 Rep Power: 2087
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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

__________________

http://www.lexellaser.com/techinfo_wavelengths.htm

Laser Safety:
http://www.laserpointersafety.com/index.html

Angular Size Calculator; use with diode angle of radiation specification to calculate the needed lens diameter for a given FL:
http://www.1728.org/angsize.htm

Divergence to spot size calculator: http://tinyurl.com/spotsize - 1 mRad is about .057 degrees which from the earth would expand to be ~10% the diameters of the moon or sun at their distances.

Divergence Calculator: http://www.pseudonomen.com/lasers/ca...alculator.html - Measure your lasers beamwidth at 1 foot & then at a further distance to calculate the divergence.

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

Laser Power Density Calculator: http://www.ophiropt.com/laser-measur...ity-calculator

How to build a laser beam expander to reduce divergence: http://tinyurl.com/BeamExpander

RHD's Relative Perceived Brightness Calculator. Compare brightness @nm: http://lsrtools.1apps.com/relativebrightness

YAG Power Calculator, i.e. convert ns @ mJ to peak power in watts http://tinyurl.com/YAG-Pulse

The forum costs more to run than donations received, if you wish to help click this link: http://laserpointerforums.com/donations.htm

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10-04-2014, 04:53 AM #2
 Banned Join Date: May 2011 Posts: 1,065 Rep Power: 0
VisibleGreen
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Re: TEM00 to TEM01 Mode Hopping 532nm

Dis-alignment I believe or damage to the diode

10-04-2014, 05:12 AM #3
 Class 3B Laser Join Date: Jan 2014 Location: Near Mosul, Iraq Posts: 4,249 Rep Power: 2087
Class 3B Laser

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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.
__________________

http://www.lexellaser.com/techinfo_wavelengths.htm

Laser Safety:
http://www.laserpointersafety.com/index.html

Angular Size Calculator; use with diode angle of radiation specification to calculate the needed lens diameter for a given FL:
http://www.1728.org/angsize.htm

Divergence to spot size calculator: http://tinyurl.com/spotsize - 1 mRad is about .057 degrees which from the earth would expand to be ~10% the diameters of the moon or sun at their distances.

Divergence Calculator: http://www.pseudonomen.com/lasers/ca...alculator.html - Measure your lasers beamwidth at 1 foot & then at a further distance to calculate the divergence.

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

Laser Power Density Calculator: http://www.ophiropt.com/laser-measur...ity-calculator

How to build a laser beam expander to reduce divergence: http://tinyurl.com/BeamExpander

RHD's Relative Perceived Brightness Calculator. Compare brightness @nm: http://lsrtools.1apps.com/relativebrightness

YAG Power Calculator, i.e. convert ns @ mJ to peak power in watts http://tinyurl.com/YAG-Pulse

The forum costs more to run than donations received, if you wish to help click this link: http://laserpointerforums.com/donations.htm

_______

Last edited by Alaskan; 10-04-2014 at 03:45 PM.

10-07-2014, 07:39 PM #4
 Class 2 Laser Join Date: Jan 2011 Posts: 333 Rep Power: 176
lazeristasUVISIR
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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?
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10-07-2014, 08:16 PM #5
 Class 3B Laser Join Date: Jul 2012 Location: IN, United States Posts: 2,862 Rep Power: 498
crazyspaz
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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 08:16 PM.

12-04-2014, 03:30 AM #6
 Class 3B Laser Join Date: Jan 2014 Location: Near Mosul, Iraq Posts: 4,249 Rep Power: 2087
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Re: TEM00 to TEM01 Mode Hopping 532nm

Thanks everyone, late to see the responses.
__________________

http://www.lexellaser.com/techinfo_wavelengths.htm

Laser Safety:
http://www.laserpointersafety.com/index.html

Angular Size Calculator; use with diode angle of radiation specification to calculate the needed lens diameter for a given FL:
http://www.1728.org/angsize.htm

Divergence to spot size calculator: http://tinyurl.com/spotsize - 1 mRad is about .057 degrees which from the earth would expand to be ~10% the diameters of the moon or sun at their distances.

Divergence Calculator: http://www.pseudonomen.com/lasers/ca...alculator.html - Measure your lasers beamwidth at 1 foot & then at a further distance to calculate the divergence.

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

Laser Power Density Calculator: http://www.ophiropt.com/laser-measur...ity-calculator

How to build a laser beam expander to reduce divergence: http://tinyurl.com/BeamExpander

RHD's Relative Perceived Brightness Calculator. Compare brightness @nm: http://lsrtools.1apps.com/relativebrightness

YAG Power Calculator, i.e. convert ns @ mJ to peak power in watts http://tinyurl.com/YAG-Pulse

The forum costs more to run than donations received, if you wish to help click this link: http://laserpointerforums.com/donations.htm

_______

12-08-2014, 03:01 AM #7
 Class 2M Laser Join Date: Sep 2007 Location: United States Posts: 634 Rep Power: 29
o_DEATH_ANG3L_o
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Re: TEM00 to TEM01 Mode Hopping 532nm

Do you have an oscilloscope?

12-08-2014, 03:06 AM #8
 Class 3B Laser Join Date: Jan 2014 Location: Near Mosul, Iraq Posts: 4,249 Rep Power: 2087
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Re: TEM00 to TEM01 Mode Hopping 532nm

Yep, 100 MHz.
__________________

http://www.lexellaser.com/techinfo_wavelengths.htm

Laser Safety:
http://www.laserpointersafety.com/index.html

Angular Size Calculator; use with diode angle of radiation specification to calculate the needed lens diameter for a given FL:
http://www.1728.org/angsize.htm

Divergence to spot size calculator: http://tinyurl.com/spotsize - 1 mRad is about .057 degrees which from the earth would expand to be ~10% the diameters of the moon or sun at their distances.

Divergence Calculator: http://www.pseudonomen.com/lasers/ca...alculator.html - Measure your lasers beamwidth at 1 foot & then at a further distance to calculate the divergence.

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

Laser Power Density Calculator: http://www.ophiropt.com/laser-measur...ity-calculator

How to build a laser beam expander to reduce divergence: http://tinyurl.com/BeamExpander

RHD's Relative Perceived Brightness Calculator. Compare brightness @nm: http://lsrtools.1apps.com/relativebrightness

YAG Power Calculator, i.e. convert ns @ mJ to peak power in watts http://tinyurl.com/YAG-Pulse

The forum costs more to run than donations received, if you wish to help click this link: http://laserpointerforums.com/donations.htm

_______

12-08-2014, 03:16 AM #9
 Class 2M Laser Join Date: Sep 2007 Location: United States Posts: 634 Rep Power: 29
o_DEATH_ANG3L_o
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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, 03:28 AM #10
 Class 3B Laser Join Date: Jan 2014 Location: Near Mosul, Iraq Posts: 4,249 Rep Power: 2087
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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.
__________________

http://www.lexellaser.com/techinfo_wavelengths.htm

Laser Safety:
http://www.laserpointersafety.com/index.html

Angular Size Calculator; use with diode angle of radiation specification to calculate the needed lens diameter for a given FL:
http://www.1728.org/angsize.htm

Divergence to spot size calculator: http://tinyurl.com/spotsize - 1 mRad is about .057 degrees which from the earth would expand to be ~10% the diameters of the moon or sun at their distances.

Divergence Calculator: http://www.pseudonomen.com/lasers/ca...alculator.html - Measure your lasers beamwidth at 1 foot & then at a further distance to calculate the divergence.

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

Laser Power Density Calculator: http://www.ophiropt.com/laser-measur...ity-calculator

How to build a laser beam expander to reduce divergence: http://tinyurl.com/BeamExpander

RHD's Relative Perceived Brightness Calculator. Compare brightness @nm: http://lsrtools.1apps.com/relativebrightness

YAG Power Calculator, i.e. convert ns @ mJ to peak power in watts http://tinyurl.com/YAG-Pulse

The forum costs more to run than donations received, if you wish to help click this link: http://laserpointerforums.com/donations.htm

_______

12-08-2014, 03:32 AM #11
 Class 2M Laser Join Date: Sep 2007 Location: United States Posts: 634 Rep Power: 29
o_DEATH_ANG3L_o
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Join Date: Sep 2007
Location: United States
Posts: 634
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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, 04:04 AM #12
 Class 3B Laser Join Date: Jan 2014 Location: Near Mosul, Iraq Posts: 4,249 Rep Power: 2087
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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.
__________________

http://www.lexellaser.com/techinfo_wavelengths.htm

Laser Safety:
http://www.laserpointersafety.com/index.html

Angular Size Calculator; use with diode angle of radiation specification to calculate the needed lens diameter for a given FL:
http://www.1728.org/angsize.htm

Divergence to spot size calculator: http://tinyurl.com/spotsize - 1 mRad is about .057 degrees which from the earth would expand to be ~10% the diameters of the moon or sun at their distances.

Divergence Calculator: http://www.pseudonomen.com/lasers/ca...alculator.html - Measure your lasers beamwidth at 1 foot & then at a further distance to calculate the divergence.

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

Laser Power Density Calculator: http://www.ophiropt.com/laser-measur...ity-calculator

How to build a laser beam expander to reduce divergence: http://tinyurl.com/BeamExpander

RHD's Relative Perceived Brightness Calculator. Compare brightness @nm: http://lsrtools.1apps.com/relativebrightness

YAG Power Calculator, i.e. convert ns @ mJ to peak power in watts http://tinyurl.com/YAG-Pulse

The forum costs more to run than donations received, if you wish to help click this link: http://laserpointerforums.com/donations.htm

_______

Last edited by Alaskan; 12-08-2014 at 04:32 AM.

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