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I am an undergraduate Mechanical Engineer and currently I am using a laser which heats and melts a surface of any material (plastic, metal etc) which is formed in powder. Although, I have managed to melt some plastic's powder, I want to put more accuracy in the control system of the laser with the temperature of the surface which is being heated. To be more specific, I want to measure, relatively accurately, the heated material's temperature and when the temperature reaches the melting point I want the laser to be turned off. I googled about the thermal radiation effect and I found about the pyrometer device. I would like to ask if there is a pyrometer which is compatible with Arduino/Tiva microprocessor with a normal range of temperatures. I found some pyrometers/contactless thermometers that can measure up to 380 degrees Celsius which is not enough since the melting point of aluminum is 660 degrees (I want to use later aluminum). Any suggestions?

Thank you for your time and for your answer in advance,

Chris

EDIT (after Jonk's suggestion):

Chamber:

The chamber currently is in room conditions (20-25 degrees of Celsius) as I just finished building it but I was thinking of inserting an inert gas later to prevent oxidization of the product (in room temperature).

Laser:

The laser is a YLIA M20 with a wavelength of 1064nm and the diameter of the beam is around 1mm. I use it at the maximum power at 20W. I want to measure the temperature of the area that the beam heats (local measurement). The laser distance between the laser and the surface is not fixed but after some experiments I made I calculated that it would be best around 100mm.

Budget:

The budget is around 500-1000 euros. If my idea for the pyrometer works and is a good solution it could be higher (1500-2000 euros).

Material:

The materials are formed in thin powder and supposed to be of any kind (plastic, metal, ceramic, glass). I cannot tell you with certainty the exact types yet because I don't know in what range I am going to use the machine I am going to build, but for a start I want to be able to measure 700 degrees of Celsius. The minimum emisivity could be at 0.5 since I don't use polished materials.

Microcontroller:

The laser's position is controlled by two motors (X and Y axis) via Arduino boards. The Z-axis of the laser is controlled through the movement of the base that hold the powder (the height of the laser in regard to the ground is fixed). The Z-axis' motor is also controlled with an Arduino board. The Arduino boards are then connected via an electronic system with a pmac board, which I use to write G code to control the movements of the laser. This whole set-up has been implemented and it works. So what I want is a control system that can also get feedback from the heated points (so for example if the melting is correct the laser can move from point to point). The microprocessor board compatibility with a non-contact thermometer is a must so I can use it in the system that I already have created.

In case I missed again something, please tell me to include it in my question.

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    \$\begingroup\$ Non-contact temperature measurement is my specialty. Pyrometry and phosphor thermometry, both. However, you've indicated a need for "accuracy" and you brought up the issue of "melting point" and also "aluminum." All of which bring in some complications when considering a practical answer. You've not mentioned allowed budget, or the range of materials and their emissivities, the surrounding environment within which the measurement must be taken, etc. You should expand the details in your question by a rather substantial margin. Chamber details, temp range, etc. \$\endgroup\$ – jonk Mar 8 '17 at 0:01
  • \$\begingroup\$ Phosphor thermometry is difficult above about \$500\:^\circ\textrm{C}\$. And it has other limitations in your case, regardless. All kinds of details affect pyrometry: ambient sources and their reflection from the surface combining with direct radiation emission, chosen wavelengths, specular vs diffuse surface, the exact geometry of the surroundings, material emissivities (probably itself temp-dependent as well as material and state of matter), observation angle and acceptance angle, target spot size... Not only a camera, but light pipes are also possible? Don't know. \$\endgroup\$ – jonk Mar 8 '17 at 1:49
  • \$\begingroup\$ Best wishes. I suspect you will have some learning ahead trying to get this right. The solution you checked is an open-loop approach and it certainly can work depending on the situation. I've worked in FAB situations where close control over a wide range is required and the effort is significant. One device I did provides milliKelvin accuracy over a range from -200 C to 1900 C using a sapphire light pipe, used on the Space Shuttle for skin temperature measurements. It takes work to get there. \$\endgroup\$ – jonk Mar 8 '17 at 19:10
  • \$\begingroup\$ Hello can i ask Ylia m20 DB25 pin layout? \$\endgroup\$ – cd lee. Nov 22 '17 at 3:16
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The easiest way to go about solving this is to have information about the material to be melted pre-loaded within Arduino code so that you can calculate exactly when to shut the laser off by also knowing the specifications of the laser. In other words, if you know how the thermal characteristics of the laser from the datasheet, you can use thermodynamics equations to calculate precisely how much time the laser needs to be turned on. The equations can be implemented within Arduino code and can directly turn the laser on and off. Again, I suggest creating a class within your code to organize the different materials that you will be melting so that all of the important parameters are included. Finally, create an interface for the user to input the type of material to be melted so that the systems knows exactly which formulas to use within code and control the laser's operation.

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    \$\begingroup\$ Nice idea Joseph, thanks a lot! I will try to find this info... \$\endgroup\$ – Chris Patr Mar 8 '17 at 15:32

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