Just got engaged to the beautiful Louise. At dinner a letter was brought out with dessert with the SEM image of the engraving on the ring and she said 'Yes'!
The engraving is 100 microns tall about the width of a human hair. It was machined with the femtosecond laser at the Photon Factory.
Something we weren't expecting was the small ripples formed by the laser inside the letters. This gave a grating which made it opalescent under the optical microscope. Sort of like the Paua shell. We use this in the lab to increase the efficiency of solar cells. We have currently only found a few metals that react to the laser in this way. So the white gold was unexpected.
The Photon Factory, my workplace, just got a new table-top scanning electron microscope (SEM), so I thought I would take some images of a Paua shell under the microscope.
The Paua shell is New Zealand's national shell. However, few know why it has opalescent colouring. This is due to how the mollusc builds its shell using layers of microscopic calcium carbonate tiles stacked like bricks. (Here is a 3D structure of the argonite)
Paua shell we had in the lab
The new SEM is able to magnify up to 60,000 times with 15kV electron beam. It also has a low vacuum setting for biological samples. For its size, it does an amazing job of imaging right down to sub-micron objects.
This is what the Paua shell looks like on the top surface, showing the ridges of the calcium carbonate forming the grating.
What else would you like to see under the new SEM?Using GIMP I overlaid the picture with the the colours of the Paua shell.