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Energy density of laser beam
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redb...@gmail.com
Jan 26, 2013, 11:22:04 AM1/26/13
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Hello!
I am building a CNC laser engraving machine and I can already see lots of possible applications of the device. One of them is to use an appropriate laser for photolitography! There's a special varnish called Positiv20 - it's sensitive to near-UV light and unexposed surface remains resistant to NaOH. After cleaning the circuit board surface with NaOH, the unexposed circuits remain intact and we can remove the copper with sodium persulfate.
The datasheet of the varnish says that with 100mJ/cm^2 we need around 10 seconds for a correct exposure. Now my question is how do I calculate energy density of my laser so that I will be able to match it to the data? I am going to use blueray laser diode because the varnish is sensitive to wavelengths between 340 to 420 nm.
I will be greatly thankful for your help. It would be the best if you told me what's the approximate energy density of blueray laser beam and I will try to match it exactly to the specs of that varnish in the experimental way, taking what you tell me into consideration to reach the best result.
I am building a CNC laser engraving machine and I can already see lots of possible applications of the device. One of them is to use an appropriate laser for photolitography! There's a special varnish called Positiv20 - it's sensitive to near-UV light and unexposed surface remains resistant to NaOH. After cleaning the circuit board surface with NaOH, the unexposed circuits remain intact and we can remove the copper with sodium persulfate.
The datasheet of the varnish says that with 100mJ/cm^2 we need around 10 seconds for a correct exposure. Now my question is how do I calculate energy density of my laser so that I will be able to match it to the data? I am going to use blueray laser diode because the varnish is sensitive to wavelengths between 340 to 420 nm.
I will be greatly thankful for your help. It would be the best if you told me what's the approximate energy density of blueray laser beam and I will try to match it exactly to the specs of that varnish in the experimental way, taking what you tell me into consideration to reach the best result.
Salmon Egg
Jan 26, 2013, 8:22:39 PM1/26/13
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In article <981e989b-6c21-4bd0...@googlegroups.com>,
If you are capable of a quick study, go to Born and Wolf and see what
the field of a plane wave is near the focal point. It is also possible
to look at what happens using gaussian optics with the Kogelnik and Li
theory. There also are studies indicating what is optimum truncating of
gaussian beams to give maximum far field irradiance (equivalent to focal
plane).
If you are not up to that, your best bet is to hire a consultant.
--
Sam
Conservatives are against Darwinism but for natural selection.
Liberals are for Darwinism but totally against any selection.
the field of a plane wave is near the focal point. It is also possible
to look at what happens using gaussian optics with the Kogelnik and Li
theory. There also are studies indicating what is optimum truncating of
gaussian beams to give maximum far field irradiance (equivalent to focal
plane).
If you are not up to that, your best bet is to hire a consultant.
--
Sam
Conservatives are against Darwinism but for natural selection.
Liberals are for Darwinism but totally against any selection.
Phil Hobbs
Jan 26, 2013, 8:41:59 PM1/26/13
to
the next generation.
To the OP: Photolithographic dose is pretty simple: dose in
joules/cm**2 is watts/cm**2 times time, and watts/cm**2 is beam power in
watts divided by pi*(spot radius)**2.
Overexposure is usually pretty benign, so it should be pretty close on
the first try, and you can do some experiments to dial it in exactly.
BTW: Do use the right eye protection. You can get goggles that absorb
Blu-Ray wavelengths for a few dollars on Amazon. Do test them to make
sure they work!
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net
http://electrooptical.net
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