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Assembly and Adjustment —
Realizing high-precision optical equipment.


Katsumi Iseki
Production Department, Nikon Instruments Company
Joined Nikon in 1982. Since then, he has been responsible for the assembly and adjustment of optical equipment, such as microscopes and semiconductor inspection equipment. Appointed as Nikon Master Craftsperson in 2009.

Katsumi Iseki is not a so-called "craftsman"—highly skilled in a single technique. This is because the assembly and adjustment of high-precision products such as microscopes and semiconductor inspection equipment requires a variety of different techniques.

We watched him working on the assembly and adjustment of the zoom section of Stereoscopic Zoom Microscope SMZ1500.

The zoom section comprises at least 20 optical components, and these must first be cleaned of all dirt. At first glance, this operation, which is known as "wiping," appears simple. However, wiping components to a uniform standard of complete cleanliness in a short time requires considerable expertise.

After being wiped clean, the components are inserted into the lens tube. They must be immediately inserted and fixed in place with absolute accuracy. Even the slightest scratch or speck of dirt cannot be permitted on an optical component. This is very precise and delicate work.

Next, while looking into the tube with a special tool, Mr. Iseki adjusts numerous parameters to within standard limits, such as the focus adjustment for both left and right eyes, the optical-axis slippage, and the amount of image shift due to change in zoom magnification. It takes a considerable number of years to acquire the skill to perform this sequence quickly. Technicians who specialize in the assembly and adjustment of optical components are rare.


Stereoscopic Zoom Microscope SMZ1500 Attains 15x magnification without the need for interchangeable lenses. The zoom section is the section with the blue plate attached.

The assembly and adjustment process for the zoom section of Stereoscopic Zoom Microscope SMZ1500


1. Components prior to assembly—the completed SMZ1500 is at left.


2. All optical components are wiped clean before assembly.


3. The metallic components and moving parts are mounted in the die cast that will form the lens tube.


4. The optical components such as the lenses are inserted.


5. The lens tube is placed on a special tool and adjusted.


6. The adjustment screw is turned very slightly.


7. The external cover is fitted.


8. The zoom section is now complete.


The difficulty of optical adjustment


In the context of the manufacturing process, "adjustment" signifies matching up the product's performance and specifications to standard ranges. If optical performance can be entirely translated into numerical values, the adjustment mechanism is operated so as to bring the parameter values to within their standard tolerances. At present, however, there are some parts for which optical performance cannot be translated into numerical values, and adjustment commonly relies on the sensitivity and experience of the technician.

For some optical systems, the technician has to adjust the focal point by visually judging the color. As the technician views the adjustment tool and turns the adjustment screw slightly, the white light from the light source separates into red, green and blue. If red is determined as the standard, the technician will need to adjust all microscope bodies under adjustment to exactly the same red. If the adjustment screw slips even slightly, the red will be too pale or too dark. The amount by which the adjustment screw is turned is so slight that it is virtually imperceptible to the human eye.

It takes considerable experience to be able to adjust the color to match. The technique required involves the technician's sensitivity, the ability to remember the color clearly, and the ability to reproduce it accurately.

Facility staff for improving and passing on technique


Mr. Iseki sums up the current situation as follows: "Our generation studied under our superiors in all areas of the factory and learned techniques by trial and error. However, I feel that this kind of environment is rare and that nowadays there is little chance for technicians to gain experience. As a result, today's technicians are unable to adapt sufficiently to changing circumstances."

In April 2010, Mr. Iseki became one of the leaders of a team made up of elite technicians. The factory staff are chiefly responsible for launching the manufacture of new products such as microscopes. The manufacturing site is also used as a venue for improving and passing on techniques.

Launching the manufacture of products involves establishing processes for a smooth manufacturing workflow and ensuring that manufacturing is conducted in a stable manner. Since this requires numerous techniques, the factory is ideal for the improvement of techniques and the development of new ones. This part of the manufacturing process, previously out-sourced, has been returned to Nikon technicians in order to enable techniques to be improved and passed on.

"I want to pass on techniques to my successors. I want to train them at the factory." A new initiative for teaching such techniques is underway. It benefits from the desire of technicians such as Mr. Iseki to train young people and pass on their knowledge.

There is always room for improvement


It is said that Mr. Iseki only has to look at the blueprint of a product to instantly get a mental picture of where to start assembly, in which order to perform the assembly, which tools to use, and what the appropriate processes and workflow are. It is also said that he thinks ahead regarding adjustments that will produce a more accurate product in a shorter time.

Mr. Iseki's approach to his work can be summed up by his motto, "There is always room for improvement." This has yielded a new awareness. Describing his observations and providing feedback at his own place of work as well as the engineering and quality control departments will naturally lead to better manufacturing at his own place of work.

"I think it was recognition of the fact that I have devised new processes rather than carried out established ones and have produced new ideas that have led to greater efficiency and improved precision that resulted in me being selected as a Nikon Master Craftsperson.

Never content with the status quo, he is constantly aiming for improvement.

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