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Latest update: 12/01/2021 18:53:09

Mitsui Optical Manufacturing Co., Ltd.

We are a world leader in providing high-quality, high-precision optical components

We are a prism manufacturer with strength in integrated production, founded more than 60 years ago. We possess processing technologies for polishing, optical thin films, bonding, and image sensor bonding. We respond to customer needs with high-mix low-volume production.


Sales Pitch

Products/processes offered
Multiplate prism unit
The three-plate prism unit is a core technology that is unique to Japan. It uses a prism to separate light entering from the lens into three primary colors (RGB), and sends each color to an image sensor (CCD/CMOS sensor) for visualization. Compared with single-panel systems that create an image using one sensor, the three-plate system enables creation of images that are more “real” and high-definition  It is therefore an indispensable technology for images that require high quality, some examples being TV cameras for broadcast stations, security cameras, and surgical cameras. According to application, various types are available such as the two-plate type, four-plate type, and visible light + infrared light.

In addition to manufacturing in accordance with customer requests, we also make in-house development efforts, striving to create new values. One example of this is the PS/IR prims unit (PS polarization and infrared imaging compatible).

These aforementioned strengths are possible because of our in-house integrated production that includes “optical design, polishing, optical thin films, bonding, and sensor bonding.” We promise product delivery that is stable in terms of quality and supply.
Optical contact
Optical contact is a technology for joining two prisms that have been polished with high precision, without using an adhesive.  The molecules inside the prism are attracted to each other and stable; however, the molecules on the surface of the prism that has been polished with high precision are in a nonbonded state and are extremely unstable (forming an active surface). When the prism surfaces polished with high precision meet each other, the molecules on the surface interact with each other and become stable like the molecules inside the prism. Optical contact bonding is a bonding method that applies these characteristics.

These days, the tendency of light sources is to push for higher power, and include the ultraviolet range. If adhesives are used, UV light cannot pass through the adhesive. Also, with high-power light sources, the adhesive itself will be damaged and deteriorate. There is also possibility of peeling occurring on the contact surface, or discoloration, causing a deterioration in performance. Further, there is the risk that scorching could occur.  To prevent such penetration of UV light or deterioration, optical contact technology that does not use adhesives is required.
Our optical contact technology has a track record of supporting laser power of 50 J/cm2 (size: 25.4 mm, wavelength: 532 nm, pulse width: 8.5 ns, shot: N-on-1) (evaluation by the Laser Research Institute)

We solve problems with processing machines, examination equipment, and in light source devices that are equipped with high power and UV light sources.
ND Filters
An ND filter is a filter that reduces the amount of light.
There is the “absorption type” that controls density by the thickness of colored glass and the “reflection type” where a reflective optical thin film is placed on the glass substrate; however, we manufacture an “antireflection type (ARND)” using optical thin film.
ARND has characteristics that eliminate the disadvantages of the absorption types and reflection types. ND filters that have hitherto been available on the market have lacked reliability due to the formation of their metal film, and their results in high-temperature and high-humidity testing have also not been good. However, at our company we have studied our film’s design and material selection as well as film formation conditions (temperature, vacuum, and vapor deposition rate). Our filters have a durability where their characteristics do not shift even in a 1,000-h high-temperature high-humidity test. Our filters have low reflectance and no restrictions on plate thickness. They also have high reliability, flatness of transmittance, and low internal reflectance. We have received high praise from our customers for them.

Because they have these characteristics, they have been particularly well received for video cameras where shutter speeds cannot be set freely. It is used for filming techniques, such as intentionally restricting depth of field by setting the aperture close to its maximum value, without adjusting the aperture to obtain proper exposure.

In addition, our company’s ARND has a density range of OD 0.1 to 0.3 and a visible range and near-infrared range for each. We offer a diverse lineup of around 20 types. Our filters are used in a wide range of applications such as by domestic and international ENG camera manufacturers and for inspection equipment.

This company is recommended by the following support organizations.

Marketing Support Department, SMRJ
Kanto Head Office, SMRJ