New recruits' profiles

The optical glass factory sits in Yuzawa City, Akita Prefecture, a region known for heavy snowfall, sometimes piled up to two meters overnight. On the day of the visit, snowflakes started to fall from the morning sky. Although Hikari Glass is part of the Nikon family, this was the first time for both Kaneko and Furui to step foot inside. Their arrival was met with a warm welcome from Kimura, who heads the Business Management Department, Business Division at Hikari Glass.

Kimura says, “Glass comes in two main types: the everyday kind we see in windows, and then there's optical glass which is used in optical units. Optical glass boasts exceptional transparency, making it significantly clearer than its regular counterpart. What's more, it has two unique characteristics: (1)refractive index, which refers to the ability to bend light transiting between different substances; (2)optical dispersion, which is the ability to spread the light out. Crafting optical glass involves blending silica, the main ingredient, with metals and rare earth elements. The blend of these materials is to prevent the har versatile and can be tailored to suit different usage, offering endless possibilities.”

“At Hikari Glass, we craft approximately 140 types of glass for spherical lenses and about 20 types for aspherical lenses. Our manufacturing recipes, which involve blending raw materials, are akin to closely guarded family secrets. They're meticulously protected as valuable intellectual property. The expertise behind lens production is truly a testament to Nikon's unique know-how.” (Kimura)

Furui, who is involved in patent work for lenses, is eagerly interested in getting closer to what's behind the scenes of lens manufacturing.

The explanation of the optical glass manufacturing process continues.

“The manufacturing process can be roughly divided into two main stages: first, the blended raw materials are melted to create glass plates, and the glass is shaped into lenses. Quality control is absolutely essential at every stage. Especially during the glass melting process, even the tiniest impurities can impact the performance and quality of the lenses. Keeping a keen eye out for foreign particles and maintaining top-notch quality are key pillars of our delicate optical glass production. So, how about we take a tour of the factory and see it all in action?” (Kimura)

Donning cold weather gear for guests, we make our way to the melting process building, stepping through the freshly fallen snow. The melting process involves melting the mixed raw materials to create a granular intermediate product called rough melt. This is followed by blending and remelting the rough melt into the shape of a plate, which is then inspected.

A highlight of the melting process is the rapid cooling of the glass from high temperatures to form the rough melt. The glass, melted to a liquid state at high temperatures, flows out of the bottom hole of the crucible in a vivid orange stream, before dropping straight into the cooling tank for rapid cooling.

Kaneko, who was an art major in college, couldn't help but express admiration.
“The moment the molten glass flows and falls is so mesmerizing!” (Kaneko)

Takahashi, who guided us on-site, explained about the cooling water. He said, “We use groundwater drawn from the abundant natural resources of the Ou Mountains and the Dewa Mountains to cool the glass which is heated to 1,200°C. Yuzawa, blessed with rich nature from the Ou and Dewa mountain ranges, is abundant with clean water. The used cooling water is purified before being discharged into the surrounding rice fields, taking into consideration the beautiful nature of Yuzawa and the surrounding environment.”

To prevent foreign particles from mixing in during the melting process, some precautions are in place. Rubber is attached to the inside of the mixer used to blend the rough melt. This is to prevent the hard glass particles from scraping against the metal walls of the mixer, which could introduce tiny specks of metal. It's said that even if the lenses are made according to the recipe, any impurities mixed in could affect their lens specs and quality.

Once the rough melt is blended and melted, it's shaped into flat plates, finally taking on the appearance of glass. As the molded glass cools, it's gently pushed out onto a conveyor belt. The transparent glass in front showcases stunning ripple-like patterns.

“It's amazingly clear, isn't it? The glass shines so beautifully!” observed Kaneko, marveling at the fact that the lens of the Nikon camera she held was crafted from such transparent glass.

The glass with ripple patterns goes through quality inspections for impurities and grain alignment before being delicately fractured into smaller pieces and moved to the processing stage. Here, pieces are adjusted for size and weight, then heated and pressed into molds, shaping square pieces of glass into the rounded forms of lenses.

As Furui tours the production line, he reflects, “I had imagined glass manufacturing to be quite risky, but I was pleased to see various precautions in place to ensure safety. It was reassuring to see the high awareness of labor safety and the safe working environment.”

The Hikari Glass production line handles grueling temperatures of up to 1,200°C, raw material in the form of a fine powder, and glass that is easily broken. Despite these challenges, the company has achieved zero occupational accidents for more than two years through dedicated safety activities. The company won the Silver Award in the Nikon Group's Workplace Improvement Activity Contest in 2023.

In the pressing process, veteran employees were manually pressing each piece of glass. Although automatic presses are installed, the more difficult lenses are pressed by hand. There were employees who heated the glass in a furnace at 700°C, while others pressed the softened glass into the shape of a lens. The entire process flows smoothly.

“This is how Nikon lenses are made, one by one, by experienced craftspersons.”
Furui closely followed the movements of these expert workers with his eyes. Ryu kindly explained how many years of experience it takes to work in a field where skill and intuition are so important.

“We have veteran employees who have been with us for 3 years at least, and 10 years at the longest. Some of our employees hold the title of Meister. Recently, we've been manufacturing more lenses with a higher degree of difficulty. We refer to lenses as 'tama' (balls), and the front element of a telephoto lens has a large diameter, about the size of a pancake. Because of its high degree of difficulty, it's pressed by hand.” (Ryu)

Before lenses are shipped, they go through a number of rigorous quality inspections. Under the light of a condenser lamp, the appearance of the pressed lenses is inspected by a new graduate employee who joined the company in 2023, checking each and every lens with a fresh and meticulous eye.

“I thought the process of carefully checking each product with the human eye was quite extraordinary. I think that Nikon's quality is supported from the beginning through their thoroughness and commitment to never producing defective products.” (Furui)

Okuyama from the Quality Engineering Section, Quality Assurance Department at Hikari Glass talked to us about the core of Hikari Glass’ quality commitment.

“We communicate well with the Manufacturing Department and provide feedback on quality-related data. I believe that one of Hikari Glass' strengths is that we work together as one across departments to manufacture products under excellent conditions.
I believe that the excellent quality of our products is the result of the focus we place on communication and the way our people pursue quality in our work.” (Okuyama)

Kodama, who is in charge of composition development and recipe development for optical glass in the Technical Development Department, also believes that the strength of optical glass lies in their enhanced communication. “Without the technology of each process, we would not be able to move forward with the development of new products. I think one of the good points of Hikari Glass is the strong cooperation and communication between departments.” (Kodama)

The final stage is the annealing process in which heat is applied to remove lens distortion.
“In this process, the curve of the temperature holding time is determined according to the refractive index of the lens. The annealing temperature and holding time are determined according to the type of lens. The longest ones can take up to a week.” (Ryu)

The process had many variables, but the data was quantified and shared.

“I always believed without a doubt that factory automation and data integration were difficult things to do. I thought that maybe optical glass factories were also analog, but was surprised to see that they've established a system to quantify the know-how of veteran craftspersons and share digital data, and that they're trying to update processes to automate them.” (Furui)

Kaneko and Furui witnessed the lens manufacturing process firsthand. What did they experience?

“I was able to experience firsthand the care that goes into each step of the process. In particular, quality control was very thorough, and various measures were taken to prevent particles from getting mixed in. I've been using Nikon cameras since I was a student, and was impressed to learn that this is where the vivid colors and delicate expressions in the photographs that the lenses deliver come from. I was also able to hear the passionate desire to create better products through close communication among employees, and I felt that this is why they're able to create higher quality products.” (Kaneko)

“I realized that optical glass is a delicate material that's always subject to breakage and damage, together with the fact that it's full of potential for high performance through a wide range of applications. Seeing each and every one of the employees perform so many inspections with the utmost care, I felt the spirit of　'zero defects' was very much alive.
What was particularly impressive was the level discussion between younger and older employees, and between people from different departments. I got the feeling that they talked to each other on a daily basis toward the singular goal of 'creating good products.' The comfortable atmosphere I felt when I opened the door to Hikari Glass for the first time may have been a manifestation of those employees' wishes.” (Furui)

What is the attraction of working at Hikari Glass? Takahashi, who works in Processing Technology Subsection and 2st Processing Section, 2nd Production Department Production Division, told us.
“I believe it's the opportunity to take on new challenges. I've been working in processing for a long time, but the experience I gained through my work in the process of manufacturing special glass materials was a turning point for me. The experience I gained back then remains valid even today.” (Takahashi)

Takahashi, who works in the Production Technology Section, 1st Production Department, Production Division, says that Hikari Glass is a place where a community can be built regardless of generation. “We inspire and motivate each other, which is one of the best things about Hikari Glass. Right now, we're working to create a comfortable working environment for our employees by converging the best of handcrafting and machines as we move forward to Vision 2030. We would like to promote manufacturing in a better environment, not only for the products we make, but also for the employees who work with us here at Hikari Glass.” (Takahashi)

Optical glass is used in the state of the art optical units and is a key essence of Nikon products. The origins of our manufacturing come from this field, backed by the skills and experience of our craftsmen, while also promoting the sharing of digital data in order to pass on superior manufacturing technology to the next generation. The reason why we can continue to produce reliable products of such high quality that can be applied to a wide range of optical units, as well as raw material formulations and manufacturing recipes that have been safeguarded within the company, perhaps due to the craftsmanship that pursue rigorous quality from the customer's perspective and the aspirations of each and every employee who sincerely tackle the process in front of them.

Optical glass, which started out as camera lenses and plays a variety of roles as the “eye” of a wide range of devices, will continue to be the foundation from which “‘A key technology solutions company in a global society where humans and machines co-create seamlessly’ can spread its wings from Akita Prefecture to the world.

WEB Site about Hikari Glass Co., Ltd.

*Title and work duties are those at the time of interview

-------------------------------------------------------------------------------------------------------------------------------------

A video introducing Nikon's production sites is now available.
From what situations are Nikon's productscreated?
We hope you will enjoy the video as well as the article to experience the passion we put into manufacturing.