laserlaser-diodelaser-driver
and I got a question about lasers. I am owning a LDS 40mw green 100mw red, and I wanted to replace the 40mw diode for a 100mw green diode. Does this requires any power supply increase? Basically a 40 to 100 mw upgrade.
Diod specification
Wavelength:532nm
Power output:100mW with 5% tolerance
Threshold current::260mA
Maximum current:360mA
Requirements Voltage:1.7~2.2V
Working Temperature:+10dgC-+40dgC
Storage Temperature:+10dgC-+50dgC
Lifepan (under normal operation)>7000hours
Size:12mmx35mm
What you have described works. If there is no inductance being connected or disconnected to the battery, capacitor is not needed. R = V / I. Find the maximum current, the battery maximum voltage, calculate the resistor, calculate the power rating of the resistor. The LED converts the electrical energy to light and heat. Cooling it with a fan would help,
If you have a regulated power supply, a simple resistor will do to take the laser above its threshold point. More complexity can involve a thermistor to lower resistance as temperature rises keeping the laser current at a slightly higher value at higher temperatures. Here is a typical laser characteristic for a device supplied by Hamamatsu: -
A more complex circuit would be needed if the laser were to be used as a datacomms device but this would involve only one extra inductor and a capacitor.
Going further, to higher powers and several manufacturers make chips that monitor the inbuilt photodiode inside a lot of lasers. They do this to protect the device from excessive currents.
Using an LM317 current limiting supply seems reasonable to me but the devil is in the detail and a circuit would be needed to be looked at for greater confidence (plus the data sheet of the laser).
Best Answer
Because the document you linked is for a laser light show device, I'll assume you want to use this for a laser light show.
In that case, you probably do not actually want the green laser to have equal power to the red laser. This is because of the luminosity curve, which shows how efficiently the human eye responds to different wavelengths of light:
This shows the human eye is near peak efficiency for green light (around 550 nm) and only about 20% efficiency for red light (around 650 nm). So for two laser beams to appear equally bright for human viewers, the red beam should actually have about 5x more power.
That said, if you just want the green beam to be brighter for some reason, you may be able to replace the diode as you suggest. You'd need the be sure the supply is able to provide enough current for the new diode, you'd want the new diode to be in the same size package as the old one, you'd want to be sure to adequately heat-sink the new device when you install it, and you'd want to be sure you can align the output beam of the new diode to the optical projection system correctly. All of these things require knowledge that might only be available in the maintenance manual of the projection system, if they're published at all.