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About diode (solid-state) lasers

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Posted April 11, 2018

In this article I want to explain a key difference between diode, CO2 and fiber lasers.

Let’s start with diode lasers.

Diode laser

The basis of a solid-state diode laser is a laser diode.  Laser diodes can have different emission wavelength. Most of them have 405 nm – 808 nm. The diodes as usually have TO3, TO5, TO9, TO18 housing.

The different is in different sizes.

The laser diode requires to have a laser driver. Good laser driver is a key to a lifetime  of the laser.

Diodes are very sensitive to the initial voltage and current.

Different diodes need different drivers.  For example the driver from NUBM44 or NUBM47 will not work for the diode M140. High quality laser driver should be able to stabilize current and be able to setup certain current and voltage that will go directly to the diode.

Another important thing is to chill the laser diode. As usual they are installed in a copper modules like this.

But still this laser copper module will not be able to distribute all heat that is generated by a diode is the power of the diode is more than 0.5 watt (500 mW).

It requires additional heatsink.

This copper laser module can be inserted

into a heatsink like this.

As soon a the laser copper module is inserted into the better heatsink it still might generate too much heat and that if why additional air blowing with, let’s say regular fan with sizes 40 *40 mm or 50*50 mm cool the heatsink.

Chilling the laser diodes is very important – cooler the module – more lifetime of the laser will be and also laser power will be higher.

Cooler the laser diode – more power it can run.

When the basic components are brought together:

  1. Laser diode
  2. Laser driver
  3. Laser copper housing
  4. Additional heatsink

It is necessary to make a focus mechanism for the laser.

Most lasers can operate with 2 type of lens:

3 element long focal lens

Or high quality G2 efficient  short focal lens.

The difference between these 2 types of lens is a focal range. 3 element lens can have focus range in 2-10 cm while G2 lens has 2-10 mm focal range (which is 10 times less)

G2 lens is more efficient and mostly used for laser cutting.

When the laser focusing is done – the final thing should be done – is a housing for the entire laser module.

Laser housing should be compatible with 3D printers and CNC machines otherwise it will not be able to setup the laser.

A lot of laser modules require additional mounting and fastening tools.

One may ask, what is so cool diode lasers comparing to fiber lasers and CO2 lasers.

First of all – the key benefit of diode (solid-state) laser is ability to make a really small unit with a weight that is not exceeding 200 grams or about ½’’. It allows to install the laser like this almost to any 3D printer or CNC machine

The is another big advantage of a diode laser module – it does not require and additional complicated power supply (12V and 7-8 amps power brick is max what you need).

So, the portability and easiness of installation to existing 3D printer or XY plotter makes diode laser a great tool for laser enthusiasts, hobbyists and makers.

Skeptics might will say that CO2 40W laser tube could have the same price as for 8 watt or 10 watt diode laser.

The thing is that high quality CO2 tube with 40W-60W output will be more expensive rather than to what people think considering a purchase on Aliexpress or Ebay.

Another disadvantage, that this tubes are quite fragile and big enough so can not be installed on a 3D printer or CNC machine.

CO2 tubes can only be installed on a special plotters which also require special power drivers. Also keep in mind that power consumption for CO2 laser machine will be much more than for diode laser machine.

As for fiber lasers – they simply do not have separate modules that can be attached to a current chassis. Entire 10 watt – 20 watt fiber laser machine would probably costs something like 10-15K USD which is times more comparing to diode laser machines.

Of course, fiber laser machines have a lot of advantages comparing to CO2 and diode laser machines but this is more like a professional and quite expensive equipment so not very affordable to beginners and intermediate experienced tech guys.

At the conclusion I must say that diode (solid-state) lasers have a great potential and is a perfect solution for someone who would like to upgrade and bring extension to its 3D printer or CNC machine.

A lot of nice things like photo engravings and engraving on metal can be done with 8 watt, 10 watt lasers with 445 nm wavelength.

Written by George I Fomitchev, CEO and a founder of Endurance

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