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Plastic material which is permeable for IR (infra red) signals 3
- Thread starter jacoolo
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Every organic compound including polymers adsorbs specific IR frequencies characteristic of what chemical bonds are in the material. This is used to identify compounds. If you go to you can search "polyethylene" and that will give you a link to the FTIR spectrum.
PMMA:
PE:
Other polymers are there too.
There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell
PMMA:
PE:
Other polymers are there too.
There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell
- Thread starter
- #5
Sounds like a TV remote or IRDA, which is usually around 800 nm, in which case, just about any clear red plastic will work.
N.B. This is normally called near IR, which extends to around 3000 nm. At that point, it's referred to as mid or medium IR. Each requires vastly different materials and devices.
TTFN
FAQ731-376
N.B. This is normally called near IR, which extends to around 3000 nm. At that point, it's referred to as mid or medium IR. Each requires vastly different materials and devices.
TTFN
FAQ731-376
patprimmer
New member
IR or infra red covers a broad band of the microwave spectrum. Various plastics transmit some in areas and block in other areas of the IR band. In fact, the transmission peaks are used to identify plastics as no two types have the same transmission and absorption characteristics.
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eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
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- #9
thx again for great replies
further details are :
The modulation is at 38khz, but the wave length of the IR is 950nm
I spoke with consultant from Basf already and he suggested me to consider Terlux(MABS)material.
I spent some time on investigation among existing parts. I noticed some parts which plays a role as glass between two houshould are made by PC(these parts hide IR antena and diplay of chanels).
Is there serious condition to consider between use such PC material between other - ABS, MABS - for little housing design?
The question
further details are :
The modulation is at 38khz, but the wave length of the IR is 950nm
I spoke with consultant from Basf already and he suggested me to consider Terlux(MABS)material.
I spent some time on investigation among existing parts. I noticed some parts which plays a role as glass between two houshould are made by PC(these parts hide IR antena and diplay of chanels).
Is there serious condition to consider between use such PC material between other - ABS, MABS - for little housing design?
The question
I have worked at BASF in the past and know quite a bit about MABS if you have a question at some point.
PC has brilliant impact resistance and very bad chemical resistance (it will shatter if you expose it to solvents or cleaning agents). PC has poor flow and thus is not great for thin walled parts. PC has very good HDT.
MABS has good impact resistance and chemical resistance. Good flow but lower HDT. The impact modifier in MABS is butadiene based so it is not suitable for use outdoors because sunlight will attack it.
Price per unit volume is about the same. PC is cheaper per kilo but has a higher density so you have to adjust the price for the density.
There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell
PC has brilliant impact resistance and very bad chemical resistance (it will shatter if you expose it to solvents or cleaning agents). PC has poor flow and thus is not great for thin walled parts. PC has very good HDT.
MABS has good impact resistance and chemical resistance. Good flow but lower HDT. The impact modifier in MABS is butadiene based so it is not suitable for use outdoors because sunlight will attack it.
Price per unit volume is about the same. PC is cheaper per kilo but has a higher density so you have to adjust the price for the density.
There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell
- Thread starter
- #11
well this device is going to be use within laptop, so I suppose the outdoor use is out of scope.
The neat thing is how to paint such material to be less transparent for human eye, and still well transparent for IR.
I am close to accept MABS compound becouse of its good conditions for filling small areas.
The neat thing is how to paint such material to be less transparent for human eye, and still well transparent for IR.
I am close to accept MABS compound becouse of its good conditions for filling small areas.
Paint? You don't paint these things. They should be molded with the correct absorbers to begin with. That's required to ensure a low SNR for the system.
But, why does it matter what the eye can see if it can't see 950 nm at all?
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FAQ731-376
But, why does it matter what the eye can see if it can't see 950 nm at all?
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FAQ731-376
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- #13
IR I do not get the clue of Your last sentence.
As I said - I need a material transparent for Infra Red, but in parallel it should be les transparent for human eye to hide what is covered inside.
Guys, please excuse me but I am not a material engineer at all so I do know I would sound as total newbie, which in the end I am
As I said - I need a material transparent for Infra Red, but in parallel it should be les transparent for human eye to hide what is covered inside.
Guys, please excuse me but I am not a material engineer at all so I do know I would sound as total newbie, which in the end I am
The gentleman may want the parts behind to be hidden for aesthetic reasons. A normal user of such devices would not be inclined to see what is inside so would not take it apart.
The gentleman asked how to make it transparent to near IR and opaque to visible light.
Maybe a bit late to help but try Makrolon 2805 or 2405.
patprimmer
New member
Ummmm What makes Makrolon opaque to visible light.
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eng-tips, by professional engineers for professional engineers
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I am not sure how they do it but the variants have been developed specifically to transmit near IR and block out visible light.
The spectrum graph for the two variants I suggested suggests theat in the visible light range transmissivity is as follows:
2805
Wavelength: <700nm, transmittance: 13%
Wavelength: >700nm, transmittance: 90%
2405
Wavelength: <700nm, transmittance: 2%
Wavelength: >700nm, transmittance: 90%
Contact BayerMaterialScience for more information.
patprimmer
New member
I don't need to. I worked for Bayer as a Market Development Engineer for Engineering Plastics for several years and spent a few months training in their labs in Leverkusen.
I have the manual at hand now but cannot scan the page and the graph, so I will quote word for word the text.
Quote
"Bayer Thermoplastics Technical Ring Binder.
Makrolon Propertes 2
2.1.1.2 Optical Properties
A knowledge of the optical properties of Makrolon is of considerable importance for it's applications in lighting engineering and optics etc.
The graph in Fig. 1" (not scanned into here) "gives a general idea of the transmission of Makrolon in the ultraviolet, visible and infrared ranges.
It can be seen that in the ultraviolet range light is absorbed totally with wavelenghs of up to approx. 275nm.
The light transmission the increases progressively with the wavelength, reaching a value of 85-89% at the beginning of the visible range above 400 nm; it then remains more or less constant up until the beginning of the infrared range. The light transmission diminishes with increasing wall thickness."
Makroln 2800 is a medium to high viscosity injection moulding grade.
Makroln 2400 is a medium to low viscosity injection moulding grade.
The 5 instead of a 0 for the last digit of the code indicates an additive to enhance mould release.
Makrolon is Bayer's trade name for their polycarbonate. There are probably now about 20 manufacturers of PC (polycarbonate) throughout the world. Lexan by GE is the other long standing well recognised trade name.
PC was mentioned as a possible material very early in this thread by Demon3 who is someone with excellent knowledge of the subject.
Dyes opaque to visible but transparent to IR was mentioned by Pud in a very early post. Pud also has a very good knowledge base, especially on processing, but also on available materials.
That is how Bayer, or anyone else makes their PC or any other normally transparent to visible light plastic opaque to visible but retain their IR transmission characteristics.
Natural colour PC is reasonably transparent to some parts of the IR spectrum, especially in the 700 to 1600 nm range where it transmits about 80% in thin sections.
To do his right you need to know:-
1) The specific spectrum of the light to be transmitted.
2) The transmission of the naturally coloured plastic in that wavelength band.
3) The transmission of dye formulation in the visible and IR in that wavelength band.
Any previous sarcastic remarks were intended to discourage a response that required this type of reply to refute misinformation. Obviously it did not work.
End of lesson.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
I have the manual at hand now but cannot scan the page and the graph, so I will quote word for word the text.
Quote
"Bayer Thermoplastics Technical Ring Binder.
Makrolon Propertes 2
2.1.1.2 Optical Properties
A knowledge of the optical properties of Makrolon is of considerable importance for it's applications in lighting engineering and optics etc.
The graph in Fig. 1" (not scanned into here) "gives a general idea of the transmission of Makrolon in the ultraviolet, visible and infrared ranges.
It can be seen that in the ultraviolet range light is absorbed totally with wavelenghs of up to approx. 275nm.
The light transmission the increases progressively with the wavelength, reaching a value of 85-89% at the beginning of the visible range above 400 nm; it then remains more or less constant up until the beginning of the infrared range. The light transmission diminishes with increasing wall thickness."
Makroln 2800 is a medium to high viscosity injection moulding grade.
Makroln 2400 is a medium to low viscosity injection moulding grade.
The 5 instead of a 0 for the last digit of the code indicates an additive to enhance mould release.
Makrolon is Bayer's trade name for their polycarbonate. There are probably now about 20 manufacturers of PC (polycarbonate) throughout the world. Lexan by GE is the other long standing well recognised trade name.
PC was mentioned as a possible material very early in this thread by Demon3 who is someone with excellent knowledge of the subject.
Dyes opaque to visible but transparent to IR was mentioned by Pud in a very early post. Pud also has a very good knowledge base, especially on processing, but also on available materials.
That is how Bayer, or anyone else makes their PC or any other normally transparent to visible light plastic opaque to visible but retain their IR transmission characteristics.
Natural colour PC is reasonably transparent to some parts of the IR spectrum, especially in the 700 to 1600 nm range where it transmits about 80% in thin sections.
To do his right you need to know:-
1) The specific spectrum of the light to be transmitted.
2) The transmission of the naturally coloured plastic in that wavelength band.
3) The transmission of dye formulation in the visible and IR in that wavelength band.
Any previous sarcastic remarks were intended to discourage a response that required this type of reply to refute misinformation. Obviously it did not work.
End of lesson.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
patprimmer
New member
Opps
I forgot to credit IRstuff's very relevant and knowledgeable contribution re wavelength band also.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
I forgot to credit IRstuff's very relevant and knowledgeable contribution re wavelength band also.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
Part of the problem appears to be sloppy terminology. "Opaque," in optical parlance, implies NO transmission. Most, if not all, NIR transmitter covers are "clear" red, i.e., they will look red with bright backlighting, and while dark, they are not "opaque."
That said, they are usually sufficiently dark enough to prevent the average person from seeing through the window into the circuitry. That said, anyone truly interested in the circuitry will simply remove the cover, or, use a NIR configured-camera to see inside.
TTFN
FAQ731-376
That said, they are usually sufficiently dark enough to prevent the average person from seeing through the window into the circuitry. That said, anyone truly interested in the circuitry will simply remove the cover, or, use a NIR configured-camera to see inside.
TTFN
FAQ731-376
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