Come See How Nikon Glass Is Made

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(Outside the Hikari Glass Factory in Akita, Japan Photo Credit: DP Review)

Nikon has had its own glass factory since fully acquiring the Hikari Glass Factory in 2004, a facility that had been making Nikon lenses for decades. Odds are if you own a Nikon lens, the glass for it was probably made there. 

The factory is located in the Akita Prefecture, about 375 miles north of Tokyo. Carey Rose and Barney Britton of DP Review were among the few very lucky journalists who have ever been allowed to set foot in the factory, and here are the highlights of that amazing trip they posted on DP Review

How are lenses made, you might be wondering?

It all starts with a powder. 

If you didn't know, glass is primarily made when silica sand is mixed with quartz and a few other things hardeners before being blended with Sodium Carbonate and Calcium Dioxide. Depending on the used of the glass you're making you'd then add lead or lanthanum oxide or a combination of both or other chemicals. Then you put it all in a crucible and heat it to over 4K degrees Fahrenheit. 

At the Hikari Plant, their secret mix of glass powder is primarily quartz it's mixed in a tumbler to ensure a proper blend.

Once the mix is ready it goes to the pre-melting process where the powder is heated to temps over 1K degrees Celsius or 1800 degrees Fahrenheit where it melts and the crucible opens up and streams the molten glass into a water bath.

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(molten glass pouring from a crucible into a water bath Photo Credit: DP Review)

The molten glass kind of hardens instantly on contact with the water creating a giant salt flake looking product called frit. 

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(Frit,  Photo Credit: DP Review)

That Frit is then tumbled and enters the fine melting process. This step is so important that the crucibles for this step are made out of platinum. They're basically making glass bars or ingots at this point. 

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(The glass ingot molds. Photo Credit: DP Review)

These glass bars are then broken by hand! Check out this crazy video they shot of a Nikon lens technician using hand tools to change the size of the bars.


The smaller pieces of glass are then checked by machine and by eye to search for imperfections. If they pass that test the next step is to find out what kind of glass they have by testing its reflective qualities which will dictate where it is used. 

Then those bars are cut down into rods and then further trimmed into tiny cubes with a machine that has no cutting surface. The spinning disk is safe to touch as it just creates friction on the glass allowing it to snap at the point of contact without creating glass dust or turning the glass opaque, it looks like they're cutting ice it's so precise. 

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(friction disk cutting the glass effortlessly. Photo Credit: DP Review)

Then those cubes are put in a rock tumbler until they resemble beach glass. Who thinks of this? It's crazy. The imperfections are marked and in this particular picture, this piece of glass is too damaged to be used as a lens. 

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(Imperfect glass cube after tumbing. Photo Credit: DP Review)

Please head over to DP Review to see the whole slideshow and find out how this little glass sugar cube becomes a flat lens that ends up in your camera.