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FrozenGate by Avery

Help if possible on laser project

Guys i appreciate the advice on starting small before i attempt this which i will do in my own time, but i am still in the planning and research stage of this project and im telling you everything i understand about it up to this point. You guys keep hammering me but its honestly all i know right now. Also it is a set task so whether its a fail or a success is on me.

All im looking for, if you wish to help are ideas and advice on the appropriate components and methods to use which will safely switch on, power, cool and drive the diodes. This will also help me understand the relationships between each part and further my knowledge in this field. Im not asking you guys to do the project for me and i also understand it might be difficult for you guys to help if you dont know the big picture. But your knowledge will help me greatly in researching what components to use and why we want to use them. Isn't what i stated i wanted the device to do, enough to help provide some ideas? (that being mainly running the diodes safely through a power outlet with a heat management system)

i do intend to use a separate 2.4 SXD for the LPC 836, will this be a problem?
 
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Don't take this on bad, BUT...

jimmy433 said:
Hey guys, im currently doing a project in laser optics and the first part requires me to construct a device which produces a combined output of 2 laser diodes (attached below).
Next is combining the lasers which im pretty confident with.
Click to expand...

jimmy433 said:
I will be sending the output of the combined laser diodes through some fiber optic and observe the output wavelengths, but i have a good understanding on that part of the project...
...Its a project for college that branches into spectroscopy where the output wavelengths is what i am to observe
Click to expand...

Nobody's college project should require 1W laser diode. And secondly your school project sounds more like an electrical engineering class.. :huh:

jimmy433 said:
i would like to implement the electronic components and integrated circuits individually just for my own educational purposes and to see the relationships between them.
Click to expand...

I'm confused, I thought this was a college project?

jimmy433 said:
I will also have heat management system preferably as a heat sink with fans which will manage the heat for both diodes
Click to expand...

There are much better ways / implementations for heat management for lasers that need high accuracy stability.

jimmy433 said:
my end task is to just observe the wavelengths once sent through some doped optical fiber which for example may or may not be used as a tool in spectroscopy...
..sensing tools like this are used on things such as the mars rover and medical devices, but im working on a very basic form of this.
Click to expand...

I think you should work much more basic stuff than this :p

jimmy433 said:
also thanks for the idea on the single mode diodes ill look into that...
Click to expand...
jimmy433 said:
But they were the laser diodes i am to work with for some reason, which i will look into further but i cant change them... ...The drivers i have are 2.4a SXD drivers i cant change them.
Click to expand...

You have already bought 300$ parts for "college" project even you are in design stage and obviously you don't have any clue about electronics or how to implement those parts you have bought??!

Sorry but, this project is poorly planned and full of "holes" and "gaps" and device you're trying to design is failed to doom. :shhh:
 
Thanks for having another dig Arctitdude, your a great help mate. As iv said it is a college project, my first big project in fact. I don't know where you got school from and as iv said in on my introduction im studying electronics and software engineering so it connects. I said it will benefit my educational understanding as i am also learning while doing this project, is that not allowed? I will have someone supervising me at all times, but im trying to get a head start on things as you can tell i havnt had any practical experience in electronics. As for the heat sink it has to be cheap where the parts should be easily accessible.

Thanks diachi ill look into it.
 
No offense, I don't have much electronics knowledge either. Never studied electronics other than some parts of the physics. But using a 2.4A driver on a 0.4A (400mA) diode is obviously overkill. By 600%! :thinking:
 
hahaha yea thank god he pointed that out, i have a few diodes to work with so i would have found that out the hard way.
 
Well, I'm glad for you that it didn't get that far. :p
 
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I really does not meant to mock you or offend you.

But you're giving us nonsense atm...

jimmy433 said:
...Also the parts i am to use should be cheap and easily accessible (commercial off the shelf stuff)...
Click to expand...

And you choose to use NDG7475? That's not my conception of cheap part?!

jimmy433 said:
But your knowledge will help me greatly in researching what components to use and why we want to use them...
Click to expand...
Ok, where is research part of that? Buying parts before you've complete your plan of your device or without any blueprint / wiring sketch is not wise.


Try to sell parts you got and start over.
Do / provide some sort of wiring sketch / plan of your device (it doesn't need to be final) So, that other members can check it and help you of if there something need to be fixed.
When the design and wiring plan is ready, you can start to resource parts for your device.

Atm you're trying to put parts together with bubble gum and glue will end up a fail.
 
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Once again i did not choose the diodes to use, cant switch them and did not buy them. and sorry by cheap parts i meant the parts i am to consider in using when constructing the device (heat sink, transformer, the driver i guess ill need for the LPC, fans, circuitry etc..) Collimating lenses, and mirrors are provided as well as mounts i think, where i will have to figure out the angles of the mirrors and mount the components appropriately.

i have found some heatsinks/housing im considering in adding to the design, NOT buying. This is just to see if im heading in the right direction of identifying the appropriate components to use, do not worry im not spending any money.

450nm 9mm focusable Laser Diode Case/Laser Diode Host with 450nm glass Lens | eBay

something along the lines of the above to use with the NDG, i wont be using the collimating lense it comes with of course. I understand its specified its suitable for the TO-5 LD which like the NDG also is around 1Watt and 9mm in diameter. Would this be a suitable choice.

Also for the LPC

40x40mm laser housing heatsink /5.6mm diode for blue red purple with M9 holder | eBay

which is said is suitable for the 650nm range and is 5.6mm.
 
Try to provide some sort of sketch / wiring plan of device first. You can resource parts later :p
 
I very much doubt that you was told to use a NDG7475. If I know any institution, safety is key. Using a Class 4 is not something they just happily just allow. And they wouldn't advise you to use a laser diode they know nothing about, so I find this whole story very odd. What sort of risk assessments are taking place surrounding your project?
I don't think you are telling us the whole story. This sounds like a project that you want to do, and you are putting the college on the backfoot. The college would be assisting you more otherwise. Messing around with Class 4's is very dangerous. And I don't understand at all why you need that much power. Do you at all have any clue what you are doing? As this and a Class 4 is a dangerous mix.
In college I used to dream up projects to do with lasers, and not just any lasers. I used to want to use Class 3B's and 4's. Was it practical for anything but my own amusement... honestly I have to say no. It was a instance of my youth.
I personally see something similar happening here. I don't see any application being successfully carried out. I don't see much in the way of sensible planning. You don't know much about the electronics side of things, and you have admitted that lasers and optics is something you are new at. Exactly what do you know about what you want to achieve? You saying you can't change the diodes mentioned sounds to me that it is not set by the college, but set by you instead.

I think this is a disaster waiting to happen. If you get as far as getting the lasers to lase, then I don't think you know anything about what to do with the laser itself. 1W of 520nm is incredibly bright and dangerous. What laser goggles do you plan to use? What type of setup are you planning to implement? How are you going to get the lasers to travel through the fibre cable? And most importantly, what is it you want to actually see happening? Please give a link or reference of some sort to what you want.
If this is indeed a college endorsed project, then you need to have a serious word with your tutors about how you are going to pass this project.

I'm not trying to be horrible, but just being honest.
 
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************ is a start-up company that will be launching a new range of gas sensors based on a new sensing technique using visible light as the excitation source. This project will develop the optical, mechanical and electrical requirements of the company’s newly acquired visible diode lasers that emit in one of three colours: blue, green or red. The project will involve designing, constructing, testing and calibrating the combined electrical-thermal-mechanical-optical system. Once the systems is ready for testing, lenses will be used to launch the light from the diodes into optical fibre. The efficiency of the launch will be measured for each of the three colours.

This was the original project description but it changed to only using green and red laser diodes and combining them, the rest is the same. Im not going to link stuff on the internet about my college as it branches into my personal life if you can understand that.

I will be in a laser lab with all the appropriate safety equipment, i can send you an email of the access form of the lab with the safety training i am to complete if you really want.

As i said my main goal is designing the pump device, which will power, manage the heat, drive and combine the laser diodes. The second part involving the optical fiber will be with the assistance of the supervisor. and the supervisor will be with me at all times so i don't accidentally burn out my eyeballs (even though i will have all the safety gear (goggles, laser safety curtains etc..)
 
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Ok, thanks for telling me a little more about what you are doing.
Now, my previous point still stands about the power. You do not in any way shape or form need that much power for sensing.
Plus you ideally do not want to be using multimode lasers.
You should be instead focusing on finding lower power single mode lasers instead for your application. <5mW is absolutely fine for sensing applications and therefore stays safe for observation and doesn't require so many safety measures.
I understand, I don't need anything regarding your personal life on here. But this would of been useful from the start.
No need to email the access form.
If those diodes are in fact the lasers specified by your brief then it is incredibly odd. There is no reason why sensing requires a 1W 520nm. Or any sensible reason why a project would require students who have no idea regarding lasers of those power level to be using Class 4's.

But do you know another huge problem I have 'detected'. Most gases have a specific absorption spectrum. You need to have wavelengths fine tuned to those absorption peaks. For instance sodium gas absorbs and emits around 589nm.
If say oxygen, CO2, Nitrogen are not affected by 520nm and 650nm then how are you going to detect it? Most dangerous gases that need detecting have absorption bands in the IR part of the spectrum.
 
I might be wrong here but i think i remember him saying once the combined laser is focused and goes through a doped optical fiber the output is of multiple wavelengths? or a changed wavelength which is what we will be measuring and where we can determine if we can use it in gas sensing.

Also just quick im curious, once the two lasers go through a diachroic mirror are they just added together or does there wavelength combine and/or change?

Also why would we rather the single mode lasers instead, is it just for the safety factor? I will definitely ask about this
 
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When you combine two lasers in this fashion, the wavelengths don't literally combine to make one at all. Like I said earlier, you will observe a colour change but a spectrometer will still display the two input wavelengths. The end wavelength doesn't change.
Only absorbance and re-emissions will lead to a change in wavelength.

However what you can pick up if if you shine the two wavelengths through a medium, is a difference in absorption depending on the absorption spectrum of the medium itself. And then you start creating a catalogue of the spectrum so you can identify what medium it was.

A hypothetical example. Not at all accurate BTW.

Base Medium (air) registered a 30000 counts for 520nm and 20000 counts for 650nm. Counts is just a generic term for what ever unit of measurement you will be using.

Medium A: 20000 counts for 520nm and 15000 counts for 650nm. This would mean the medium has a pretty even amount of absorption for both 520 and 650nm.
Medium B: 10000 counts for 520nm and 18000 counts for 650nm. This would mean the medium has a high amount of absorption for 520nm and low absorption for 650nm.

If you detect a unknown medium following the same lines of your test medium B then you can be fairly certain that it is in fact a match.

I don't know how your college is proposing to go about detecting individual gases, but this is the best of what I can get out of it.
 
Thanks i understand where your coming from, but keep in mind this probably wont be used in any practical sense, it is to just mainly experiment to see if we can use these diodes in this kind of application.

could you also explain if you dont mind why would we rather the single mode lasers instead of multi mode, i understand multimode diodes are usually set to emit multiple wavelengths (beams) and as for single mode i assume it emits one wavelength with lower divergence but i could be wrong.
 
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