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Education Time Tellurium






Cool :P though he said infra red lasers are like heat rays, but it really depends on the wavelength
 
Hey I was an optician in the 80's and we made IR lenses mostly (at Exotic Materials) . The truth is Germanium when totally pure is not perfectly transparent to IR, it needs a "dopant' a very small amount of actinium or arsenic is added in order to get the 99% or so transparency (only once coated for IR anti-reflection) the coatings were also interesting, one kind used multi-layers of elements including thorium. I ran a "Hard Carbon Coating machine, which used plasma and cyclohexane, (a carbon source), to make thin layer man made diamond on the germanium so a wiper with sand after 500 revolutions would not mark, scratch or remove the diamond coat which looked like a very shinny black shoe polish surface. With Hard Carbon the lens or window of doped germanium would pass 99.5% of the IR from 900 to 1600nm these were used on the Apache helicopters' Pilot Night Vision System, (PNVS) and the Tactical Acquisition and Deployment System (TADS) ( Guided Missile system) on the outer most optical surfaces.
 
Wow thats really cool, i never knew any of that.

For those that don't know cyclohexane is an fossil fuel or hydrocarbon ( made up of hydrogen and carbon ), cyclohexane has the formula C[sub]6[/sub]H[sub]12[/sub] and burns/evaporates more readily than gasoline which is octane C[sub]8[/sub]H[sub]18[/sub], the structure of cyclohexane is a ring, as with all other cycloalkanes.

there you go another chemistry lesson to go with the videos :P

Diachi
 
scopeguy20 said:
Hey I was an optician in the 80's and we made IR lenses mostly (at Exotic Materials) .  The truth is Germanium when totally pure is not perfectly transparent to IR, it needs a "dopant'  a very small amount of actinium or arsenic is added in order to get the 99% or so transparency (only once coated for IR anti-reflection)  the coatings were also interesting, one kind used multi-layers of elements including thorium.  I ran a "Hard Carbon Coating machine, which used plasma and cyclohexane, (a carbon source), to make thin layer man made diamond on the germanium so a wiper with sand after 500 revolutions would not mark, scratch or remove the diamond coat which looked like a very shinny black shoe polish surface.  With Hard Carbon the lens or window of doped germanium would pass 99.5% of the IR from 900 to 1600nm these were used on the Apache helicopters' Pilot Night Vision System, (PNVS) and the Tactical Acquisition and Deployment System (TADS) ( Guided Missile system) on the outer most optical surfaces.
Click to expand...


MMMmmm, PECVD. Do you happen to know more about the tool? Inductively coupled plasma? My old lab has a PECVD system for diamond-like carbon as well, it mostly just used methane, nothing as fancy as cyclohexane. Word up to all the other thin film engineers. I'm partial to sputtering, myself, but I'm doing some evaporation nowadays too.
 
I do know the the "vapor" (carbon nuclei) is driven like a particle accelerator and hits the surface with enough energy to fuse together to get the cubic crystal structure. If the turbo molecular pump is not keeping the plasma at a high enough vacuum, then more of the component micro-crystals in the film, will be hexagonal, which of course is graphite and then the coating would remove with plain water. Also, I was told other carbon sources would work in the Leybold-Heraus coating machine. This unit also, had such high voltage I forget the number.
 
The crystal he was holding in the tellurium video is a Cadmium Telluride OPO element.

Btw Oh check out the Cesium video... I got a vial of it TWICE that size, a quarter kilogram of it. :o
 
heruursciences said:
The crystal he was holding in the tellurium video is a Cadmium Telluride OPO element.

Btw Oh check out the Cesium video... I got a vial of it TWICE that size, a quarter kilogram of it.  :o
Click to expand...
the cesium to cool id love to have some of that
 
Here is the picture of the cesium for your drooling enjoyment.

It is 5N 99.999+ purity and came from a company that built cesium beam time standards. It would be a terrible waste to toss it in water, especially since it's probably worth it's weight in gold... literally...
 

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