Mike Barkley

Possibly add a grid tied inverter that will dump the excess to the grid.

Electron microscopy begins with generating an electron beam. This picture is the business end of a (defective) lanthanum hexaboride (LaB6) filament. I looked up the current prices ... $1300 so not cheap. A tungsten filament is much cheaper. Those are used too. Not as good as LaB6 but considerably cheaper. The filament is heated so it emits electrons. It also has a high voltage applied to it. It is called the accelerating voltage. After the electrons leave the electron gun they go through a series of electromagnetic lenses that shape, position, & focus the beam onto a grounded sample. If the sample is not conductive it is usually sputter coated with a thin layer of carbon or sometimes gold so that it conducts. The high voltage slams the electron beam into the grounded sample which then completes the circuit like every electronic circuit does. BUT the interaction of the beam with the sample causes other types of electrons & x-rays to be emitted. Various detectors can detect each of those things. Each analyzes the sample in different ways.

The part inside the cage detects what is called secondary electrons & creates the main type of micrograph image one sees out in the world. It has a voltage applied to it to attract the secondary electrons. The dark thing around the central dark hole is called a backscatter detector. It is more specialized.

So now to the point of why the original pix I sent for this are so unusual. Instead of a conductive sample I used a glass light bulb (nonconductive) as the sample. Zapped it with a 40 kilovolt beam for a few seconds. Since the sample was nonconductive those electrons could not complete the circuit so it charged up the light bulb glass. Then I turned the accelerating voltage down to a only a few kilovolts. When that beam hit the highly charged glass it deflected those beam electrons in all directions. Which then smashed into all the internal chamber parts you see in the picture. Then the secondary electrons from that abnormal interaction were detected & processed by the detector & video circuitry in normal fashion.  

I warned y'all it was geeky.

The last pictures are more typical of real life use.

That's a good guess Anna. It's in the ballpark at least. The pix I sent are the scanning electron microscope version of a selfie. I will describe how the pix were made after the sun comes up & some more coffee is down.

Some electron microscopes have spectrometers attached as accessories. Energy dispersive (EDS) & wavelength dispersive (WDS). EDS determines which elements are in an unknown material. Say a glob of metal. EDS will tell the user it's iron, nickel, & copper for example. WDS will give the exact percentages of each.

This post will clarify a point or muddy the waters. Probably both. It is intentionally vague but more specific details will be added later. It's a bit of a deep geeky rabbit hole but we need to go down it a little to understand why I think this is such a cool picture. In the words of young Frankenstein ... it's abynormal.

In a roundabout but important way light is involved. A primary something comes out of the dark hole in the center of the bottom picture. Which generates secondary somethings that are collected by a device inside the screen. When the secondary somethings hit the device they generate photons (light). That light is extremely faint though. Not visible to human eyes & light never enters the chamber. The curved part attached to the screen device is one big fiber optic strand about as thick as your thumb which transmits the faint light outside the vacuum chamber. It is then strengthened enough to barely be visible.

Theresa, that is getting close. No heat involved but it is a chamber. A vacuum chamber to be precise. So for all practical purposes there is zero gas. It's almost outer space level vacuum.

I was asked to give a sense of scale. The pix are more or less life size. Nothing huge, nothing tiny.

I'm not asking specifically what the wire cage is. I'm looking for what the entire scene is about. The total of everything seen in the pix.

Maybe Jay's thing is a holder for a filter to be used as a paint strainer.

In a way you're lukewarm but no. This is done in complete darkness.

In the words of Monty Python ... and now for something completely different. Any guesses what this is?

Haven't owned or watched tv in about 20 years. Maybe more. Don't miss it one bit. Not even a little.

As Anne was saying ...