BAD/DEFECTIVE
LASER MODULES



Red diode laser modules (two modules out of three) sent by J.B. in Belgium (received 08-18-09) and subsequently damaged by the postal service in transit - these lasers were probably exposed to electrostatic charge or irradiated with X-radiation (X-rays) during a security scan.




Beam photograph (module #2) on the test target at 18".
Photograph was deliberately left uncropped so that the beam shape can be seen.

Note the dark stripe...this is what's known in the diode laser industry as a "dark line defect"; I'm not certain what the root cause is, but exposure to static electric charge or X-radiation ("X-rays") during a postal security scan (with the lasers not placed in an antistatic bag for shipment) may have something to do with its formation.

The following power output measurements were made:

Vin=3.306 volts
2.6040mW (distance to sensor 0cm)
1.8879mW (distance to sensor 1cm)
0.9207mW (distance to sensor 2cm)

Vin=4.500 volts
3.0225mW (distance to sensor 0cm)
2.0274mW (distance to sensor 1cm)
1.0974mW (distance to sensor 2cm)




Beam photograph (bare diode module) on the test target at 18".
Photograph was deliberately left uncropped so that the beam shape can be seen.
Note the "dark line defect" in the beam; in this case, power output has also been nocked way down.

The following power output measurements were made:

Vin=3.306 volts
242.730W (0.242730mW) (distance to sensor 0cm)
139.500W (0.139500mW) (distance to sensor 1cm)
93.9300W (0.939300mW) (distance to sensor 2cm)

Vin=4.500 volts
217.434W (0.217434mW) (distance to sensor 0cm)
138.570W (0.138570mW) (distance to sensor 1cm)
96.8130W (0.968130mW) (distance to sensor 2cm)



Spectrographic plot
Spectrographic analysis of module #2.


Spectrographic plot
Same as above; spectrometer's response narrowed
to a band between 650nm and 670nm.
As you can see, the peak wavelength is ~661.30nm,
and the spectral line halfwidth is ~1.30nm.


Spectrographic plot
Spectrographic analysis of module #3 (bare diode); Vin=4.500 volts.


Spectrographic plot
Same as above; spectrometer's response narrowed
to a band between 600nm and 710nm.
As you can see, the peak wavelength is ~668.10nm,
and the spectral line halfwidth is ~14.850nm.


(Update 08-21-09): New spectroscopic analyses performed at a lower Vin.

Spectrographic plot
Spectrographic analysis of module #3 (bare diode); Vin=3.306 volts.


Spectrographic plot
Same as above; spectrometer's response narrowed
to a band between 600nm and 710nm.
As you can see, the peak wavelength is ~660.01nm,
and the spectral line halfwidth is ~22.00nm.

USB2000 spectrometer graciously donated by P.L.


ProMetric analysis
Beam cross-sectional analysis (module #2, X-axis).


ProMetric analysis
Beam cross-sectional analysis (module #2, Y-axis).

Images made using the ProMetric System by Radiant Imaging.

I wanted to perform beam cross-sectional analyses on module #3 (with bare diode), but its intensity was just too low.


The If (input current) at a Vin=4.500 volts (closed-circuit, not open-circuit), using an Aixiz laser diode module power supply unit specifically made for this application are as follows:

Module #2: 60.10mA
Module #3 (bare diode): 81.80mA

The If (input current) at a Vin=3.306 volts (closed-circuit, not open-circuit), using an adjustable voltage laboratory power supply unit are as follows:

Module #2: 45.60mA
Module #3 (bare diode): 60.20mA









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