When coating an optical lens, the design of the coating as well as the lens will change depending on the various product applications. Let’s take a look at some of the typical coatings used for optical lenses.

(1) AR coating (Anti-Reflection coat)

This coat is used to increase the amount of light transmitted through the lens by lowering the amount of reflected light on the substrate (lens) surface.

Let’s call the substrate BK-7.
(BK-7/optical glass – used as a substrate for mirrors, beam splitters, and various vapor deposition filters, in addition to lenses and prisms)
The reflectivity is reduced by adding one to three layers of dielectric film to the substrate.

The single-layer coating reduces the overall reflectivity. (4.2% to about 1.3%)
2-layer coating lowers the reflectance of only certain wavelengths. (Around 550nm)
The 3-layer coating lowers the reflectance of the entire wavelength. (450 to 700nm)
Therefore, it is necessary to select the type of coating depending on the product application.

(2) Half Mirror Coat (HMT)

Half Mirror Coat is a coating that separates the amount of transmitted light and the amount of reflected light. When the light is divided 50:50, it is called half mirror coat.

Depending on the product standard, it is possible to design membranes with various optical separations, such as 80:20 or 60:40, to achieve detailed separation settings.

(3) Long Wave Pass Filter (LWF)

A coating that blocks the amount of light transmitted at short wavelengths and allows the amount of light transmitted at long wavelengths to pass through.

(4) Short Wave Pass Filter

This is a coating that transmits the amount of transmitted light on the short wavelength side and blocks the amount of transmitted light on the long wavelength side.

When the wavelength is more than 700nm (∴ Transmits the amount of visible light, and blocks the amount of light in the infrared region)
Also known as IR Cut Filter (InfraRed Cut Filter).

(5) Band pass filter (Band Pass Filter)

This is a coating that transmits light only in a certain range of wavelengths and blocks light in other wavelengths.

Depending on the product standard, the wavelength range can be further narrowed by designing the membrane to pass through.

(6) Dielectric mirror

This is a coating that uses a dielectric as the deposition material to increase the amount of reflected light by limiting it to a certain range of wavelengths.

It is characterized by changes in the spectral characteristic waveform as the angle of incidence changes. Dielectric mirrors are often selected when durability testing of the product itself is required.

(7) Metallic mirror (aluminum mirror)

This coating uses aluminum (metal) as the vapor deposition material to increase the amount of reflected light over the entire wavelength range.

By using a metallic film, it is possible to obtain a high amount of reflected light over the entire wavelength, but it is not possible to obtain a high amount of reflected light at a specific wavelength at the dielectric film level. However, changing the angle of arrival does not affect the change in the amount of reflected light.

Whether to use dielectric mirror coating or metal mirror coating should be selected according to the product specifications.

For all your optical design needs, contact Optical Design Technology Navi!

TOYOTEC Corporation, the company that operates Optical Design Technology Navi, is a comprehensive optomechatronics optical manufacturer that designs and develops products from scratch to meet customer needs, and provides integrated support from design to commercialization.

I want a product like this… “Is it possible to do this with lenses? Optical Design Technology Navi, a group of optical design professionals, is the answer to these questions. If you have any questions about optical design, please feel free to contact us at Optical Design Technology Navigator.

The post 7 Types of Thin Films (Coatings) Used in Optical Lenses. appeared first on Toyotec Solutions.

In this way, aspherical lenses make it possible to reduce the size and weight of products, and even to cut costs. However, the production of aspherical lenses requires a very high level of manufacturing technology.

In this section, we will explain the features, advantages / disadvantages, and manufacturing methods of aspheric lenses.

Principles of Light Collection and Divergence and Classification of Lenses by Surface Type

There are many different types of lenses. They can be broadly classified as the following according to the principle of light focusing and divergence and the type of surface.

Lenses ① to ⑤ are lenses that have a focusing and diverging effect solely due to refraction on the lens surface. Of these, lenses ① to ④ have a continuous smooth surface, while lens ⑤ has a lens surface that is divided into discontinuous zones.

On the other hand, in the case of ⑥, the refractive index inside the lens is not homogeneous but distributed, and in the case of ⑦, light is focused and diverged by using the diffraction effect on the surface instead of refraction.

Lenses ② to ④ are lenses with continuous, smooth, non-spherical lens surfaces and are called aspherical lenses in a broad sense. ② is a lens with an aspheric surface that is axi-symmetric (rotationally symmetric) with respect to the optical axis of the lens, and is often used in imaging optical systems. Lenses ③ to ④ are aspheric lenses that do not have axisymmetry (rotational symmetry) with respect to the optical axis of the lens, and are mainly used in lighting and focusing optical systems.

＞＞What Problems do Spherical Lenses Have?

What is an Aspheric Lens?

An aspheric lens is a lens with a non-spherical lens surface.

Features of Aspheric Lenses

Aspherical surfaces are classified into two categories: axi-symmetric aspherical surfaces, which have axial symmetry (rotational symmetry) with respect to the lens optical axis, and aspherical surfaces, which do not have axial symmetry. Each type of aspheric surface has its own characteristics.

Aberration reduction

Axi-symmetric aspheres include rotational parabolas, rotational hyperbolic surfaces, rotational elliptic surfaces, and rotational quadric surfaces. In imaging optics, the use of such axisymmetric aspheres increases the degree of freedom in shape and makes it possible to suppress aberrations that would be difficult with spherical lenses alone.

In addition, when axi-symmetric aspheres are used in illumination and focusing optics, it is possible to achieve uniform illumination distribution and increase the degree of freedom in ray control.

Addition of new functions

Aspheres that are not axi-symmetrical (rotationally symmetrical) can be used to change the magnification of vertical and horizontal images in imaging optics. Also, in illumination and focusing optics, light emitted from a point light source can be projected in the form of a line. In this way, aspheres that are not axisymmetric (rotationally symmetric) can achieve new functions that cannot be achieved with spherical lenses alone.

Advantages of aspheric lens

In this section, we will introduce the advantages and disadvantages of axi-symmetric (rotationally symmetric) aspheres in imaging optics. There are three major advantages.

Number of lenses can be reduced

In imaging optics, multiple spherical lenses are used in combination to reduce aberrations such as image blur and distortion. By using aspherical lenses, it is possible to reduce the number of lenses while maintaining the same performance. For example, you can achieve the same performance of an 5-spherical-lens optical system with a total of 4 lenses using 2 spherical lenses and 2 aspherical lenses.

Lens units can be made smaller and lighter

The fewer the number of lenses, the more compact and lighter the optical unit can be.

Cost reduction for optical products

With fewer lenses, it is possible to reduce lens materials, processing costs, and assembly man-hours, leading to overall cost reductions.

Disadvantages of aspheric lenses

On the other hand, aspheric lenses have their own disadvantages, too.

Expensive if produced in small quantities

A spherical glass lens is processed by grinding one surface at a time, but grinding and polishing an aspherical lens one surface at a time would be very expensive. For this reason, aspheric shapes are generally processed into molds, which are then transferred and molded onto glass or plastic.

Although the time required for transfer and molding is shorter than for the spherical polishing process, manufacturing of precision aspheric molds (which incurs cost) in advance are necessary. For this reason, consideration of whether or not to use aspheric lens prior to production, based on the estimated total cost of the production volume is necessary.

High processing difficulty

Spherical surfaces are characterized by the fact that the radius of curvature is the same at all positions on the sphere, and this leads to the fact that they are easy to polish and high precision can be obtained. On the other hand, aspheric lenses require the radius of curvature to be made different depending on the position, which requires precision mold processing and technology to precisely transfer and mold the aspheric shape.

Manufacturing of Aspheric Lenses

The method of manufacturing aspherical lenses by transferring and molding the aspherical shape of the mold onto the lens requires three technologies: ultra-precision mold processing technology, ultra-precision transfer and molding technology, and precision measurement and evaluation technology for these surface shapes.

At Optical Design Technology Navigator, we use state-of -the-art ultra-precision processing machines to process aspheric surfaces on a sub-micron order, transfer these aspheric surfaces using molding technology that incorporates a high level of know-how, and then transfer these aspheric surfaces into an ultra-precision 3D mold.

Optical Design Technology Navigator will solve all your needs for aspherical lens manufacture!

TOYOTEC, operator of the Optical Design Technology Navigator, is an all-around optical manufacturer with proficiency in optical, mechanical, and electronical technology. We can design and develop products from scratch based on our customers’ needs, and provides integrated support from design to productization. In addition to manufacturing aspheric lenses, we offer one-stop manufacturing services from ultra-precision machining of lens cores to the design and assembly of lens units, including systems and peripheral components.

If you are thinking about something like,
“If only there was a product like this…”, or, “Is it possible to do these kind of things with lenses?”, Optical Design Technology Navigator, a website operated by a group of optical design professionals, is the place to go. If you have any questions about optical design, please feel free to contact us at Optical Design Technology Navigator.

The post What is an Aspherical Lens? About its Features and Benefits appeared first on Toyotec Solutions.

In this section, we will compare glass lenses and plastic lenses from various angles and explain the trends and selection points of plastic materials.

Glass Lenses and Plastic Lenses

In general, glass lenses are superior to plastic lenses in the following ways ;

● Resistant to environmental changes such as temperature and humidity
● High refractive index
● Abbe number, which expresses the degree of dispersion of light
● Resistant to light from wavelengths outside of visible light, such as ultraviolet and infrared rays.

A decade ago, all lenses used in film cameras and interchangeable lenses were spherical glass lenses that had been polished. In the 2000s, digital cameras began to use aspherical plastic lenses or aspherical glass lenses instead of spherical glass lenses. The reason for this is that the trend toward miniaturization has progressed, as seen in compact digital cameras. Also, the performance and characteristics of the resin material for plastic lenses improved.

Later, with the rise of smartphones, there was a demand for even smaller and thinner products, and the optical system itself also needed to be smaller, so plastic lenses became more and more widely used.

In this way, plastic lenses have an advantage over glass lenses in reducing the size and weight of products. In general, plastic lenses have an advantage over glass lenses in the following points ;

● With the same volume, a plastic lens is half as light as a glass lens.
● High degree of freedom in shape
● Mass production at low unit cost

PMMA ( Acrylic ) and PC ( Polycarbonate ) were the main resin materials for optical plastic lenses.
The characteristics of PMMA resin material include high Abbe number, low birefringence, and high surface hardness, while PC resin material features relatively high refractive index, high impact resistance, and high heat resistance.
Mainly Japanese material manufacturers competed with each other for adoption in compact digital cameras and smartphones, and resin materials that further improved the performance of PMMA and PC were developed one after another.

These include materials such as : ZEON’s Zeonex K26R and F52R (COP), Mitsui Chemicals’ APEL (COC), Osaka Gas Chemical’s OKP series, which is an improved PC, and Mitsubishi Gas Chemical’s Iupizeta EP Series.

※In-house comparison

Testing of Resin Materials

We have been testing new plastic lens materials with improved performance from the perspective of molding manufacturers. Using molds for sample plate molding, we have compared various items such as moldability, ease of surface accuracy, ease of dust and foreign matter generation, and degree of birefringence. One of the key factors in material selection is to determine which resin materials are easy for us to use.

With our experience in handling a variety of resin materials, we are able to propose the most suitable resin material for our customers’ product applications and required specifications.

Birefringence Check

※In-house Comparison
Product Diameter(Outer) : φ25mm (Mirror surface flat range φ18mm)
Thickness：3㎜
Measuring Equipment: Polarizer Cross-Nicol (Image)

Optical Design Technology Navigator will solve all your needs for optical design!

TOYOTEC, operator of the Optical Design Technology Navigator, is an all-around optical manufacturer with proficiency in optical, mechanical, and electronical technology. We can design and develop products from scratch based on our customers’ needs, and provides integrated support from design to productization.

If you are thinking about something like,
“If only there was a product like this…”, or, “Is it possible to do these kind of things with lenses?”, Optical Design Technology Navigator, a website operated by a group of optical design professionals, is the place to go. If you have any questions about optical design, please feel free to contact us at Optical Design Technology Navigator.

The post Resin Material Trends and Selection Points appeared first on Toyotec Solutions.

What is Optical Design?

“Optical design” refers to the design of an entire optical system by combining lenses, mirrors, and other components. Most of the design is about the lens itself, but since it also includes the design of reflectors and prisms, the term is often referred as “optical design” instead of “lens design”.

There are two stages in the optical design process: the specification design stage (defining the requirements) , where the specifications of the optical system itself are considered and set, depending on what functions and performances are required, and the detailed design stage, where the materials and shapes are specified based on the specifications.

In the specification design stage, the required specifications for the functional unit is converted/allocated to the specifications of the individual functional components such as the optical system and the photosensor. The individual specifications will be designed to meet the required specifications of the original functional unit when they are combined. The optical system has unique specification items such as focal length and f-number, and requires optical expertise.

In the detailed design stage, the number of lenses, other optical components such as mirrors, the shape and thickness of the surfaces, and the placement of each component are optimized based on the optical specifications. At the same time, the workability of the optical components and the method of holding and fixing them are also taken into consideration as we proceed with the design.

As you can see from the explanation above, optical design is a high-level design that requires not only knowledge of optics and design skills, but also a wide range of knowledge regarding elemental components such as photodetectors and light sources, materials, processing methods, and mechanical design. Japanese Optical Design has made great technological breakthroughs along with the rise of the camera industry after World War II, and based on this technology, it has been applied to various fields to reach the highest level in the world.

Various Optical Designs

Optical systems are functional components that control light, and can be classified into two main types. One is imaging optics, and the other is illumination and condensing optics. The two types have different indexes and methods. Imaging optics, as it literally means, has the function of imaging the light coming from an object onto a photodetector.

The photodetector is often a solid-state image sensor consisting of many pixels, like the image sensor of a digital camera, but it can also be the human eye(retina), as in a telescope. Design indexes include image sharpness, contrast, and distortion.

On the other hand, lighting and condensing optics are required to properly project light emitted from a light source onto an object, such as room lighting or stage spotlights. Distribution of illuminance, uniformity and condensing ability will be the indexes for these kind of optics. In some cases, condensing optics are used together with light receivers, such as parabolic mirrors for solar light condensation.

As you can see, there are two main types of optical design, but if you classify by the application of the optical system, there are many different types of optical design. The following is only a part of the different types for each application.

Optical Design:

● for object imaging (digital cameras, smartphones, etc.)
● for object recognition (OCR, security, etc.)
● for distance measurement (LiDAR, etc.)
● for the projection (projectors, steppers, etc.)
● for uniform illumination (desk light, etc.)
● for ophthalmoscopy (loupe, glasses, microscope, telescope, binoculars, etc.)
● for energy focusing (sunlight focusing, laser processing machines,
● medical equipment, etc.)

Optical design differs for these applications. For example, optical design for object imaging and for object recognition sounds similar, but while the former is the design of an optical system that can capture various objects in various lighting environments and distances, the latter is the design of a high quality
optical system for a specific object in a specific lighting environment and distance.

Even if the application and purpose are the same, the optical design required for each product is different. For example, loupes and microscopes are the same in that they are used to magnify and observe small objects with the human eye, but the magnification rate and application scene are very different, and the required performance, size, price, and other aspects of optical design are also very different.

The Elements of Optical Design

Optical design handles a variety of components depending on the purpose.
For example, the following are some of the components.

● Lens Material: Plastic, glass, and infrared-transparent material, etc.
● Optical Elements: lenses, mirrors, prisms, diffraction gratings, etc.
● Coatings: metal mirrors, multilayer filters, etc.
● Light source: Halogen lamp, LED, laser, etc.
● Photodetectors: Image sensors(CMOS,CCD), etc.

By properly handling these elements, a variety of optical designs can be made.

TOYOTEC, the operator of Optical Design Technology Navigator, provides support in terms of both optimal optical design and high-precision manufacturing technology in accordance with the customer’s operating environment and requirements.

Optical Design Methods

TOYOTEC uses a software dedicated in optical design. This software is equipped with a function to track light rays passing through a lens or mirror surface by applying Snell’s law. By tracking a large number of rays, it is possible to evaluate the state of image formation and condensation.

We proceed with the design using functions to control the shape of the lens and mirror surface and the thickness of the lens targeting this evaluation detail. Of course, it goes without saying that the knowledge of optics and skill for the software are necessary to properly execute the optical design.

TOYOTEC, which operates Optical Design Technology Navigator, uses Zemax and Code V software for optical design.

Optical Design Applications

Your daily life is filled with products that use a variety of optical designs. For example, smartphone cameras, which many of us carry around with us, are a typical example of a product that uses optical design to highly optimize all specifications such as thinness, weight, performance, and price. Optical design technology is also used in many other areas of our daily lives, such as eyeglasses, cameras, security cameras, copy machines, automated driving, and medical equipment.

In the industrial field, optical design is used in public transportation, warehouses, sensors, electron microscopes. It is even used in the space field,
contributing to the further development of science and technology. In addition, we are in the midst of advanced technological advances such as 5G and CASE, and the need for optical sensors and optical systems is expected to increase further in the future.

Optical Design Technology Navigator will solve all your optical design needs!

TOYOTEC, operator of the Optical Design Technology Navigator, is an all-around optical manufacturer with proficiency in optical, mechanical, and electronical technology. We ca design and develop products from scratch based on our customers’ needs, and provides integrated support from design to productization.

If you are thinking about something like, “If only there was a product like this…”, or, “Is it possible to do these kind of things with lenses?”, Optical Design Technology Navigator, a website operated by a group of optical design professionals, is the place to go. If you have any questions about optical design, please feel free to contact us at Optical Design Technology Navigator.

The post What is Optical Design? appeared first on Toyotec Solutions.

Lenses come in a variety of shapes, but the most popular of them all is the spherical lens. It is a lens in which both surfaces are spherical. Despite its popularity, spherical lenses inevitably have a problem called “aberration,” which causes blurring and distortion of the image.
Here, we will explain the types and characteristics of spherical lenses and the problems that relate with spherical lenses.

Principles of Light Collection, Divergence and Classification of Lenses by Surface Type

There are many different types of lenses. They can be broadly classified as the following according to the principle of light focusing and divergence and the type of surface.

Lenses ① to ⑤ are lenses that have a focusing and diverging effect solely due to refraction on the lens surface. Of these, lenses ① to ④ have a continuous smooth surface, while lens ⑤ has a lens surface that is divided into discontinuous zones.
On the other hand, in the case of ⑥, the refractive index inside the lens is not homogeneous but distributed, and in the case of ⑦, light is focused and diverged by using the diffraction effect on the surface instead of refraction.

Classifying Lenses by Cross-sectional Shape

There are various types of lenses that have a focusing and diverging effect only by refraction on the lens surface and also have a continuous smooth lens surface. They can be classified by the cross-sectional shape of the lens as follows;

Of these above, ① to ③ are classified as convex lenses and ④ to ⑥ are classified as concave lenses. A convex lens focuses light, while a concave lens diverts it. A ①biconvex lens is one in which both surfaces are convex. Similarly, ④biconcave lenses have concave surfaces on both sides. ②Plano-convex lenses and ⑤plano-concave lenses are lenses that have convex and concave surfaces on one side, respectively, but flat surfaces on the other side.

A meniscus lens is a lens with a crescent-shaped cross-section. One side of the lens is convex and the other side is concave. Both convex and concave meniscus lenses seem to have the same shape, but the difference is that the center of the lens is thicker in convex meniscus lenses and the periphery of the lens is thicker in concave meniscus lenses. Whether the center of the lens is thicker or the periphery is thicker is what distinguishes convex lenses and concave lenses, with lenses ① to ③ having a thicker center and lenses ④ to ⑥ having a thicker periphery.

Problems with Spherical Lenses

A spherical lens is a lens in which both surfaces of the lens are made of spheres. Spherical lenses are often used in all kinds of situations. The reason why It is so popular is that they are relatively easy to process. In glass lenses, each lens surface is polished to make a smooth surface, but in the polishing process, spherical and flat surfaces are inexpensive and easy to secure accuracy. As stated above, spherical lenses are relatively easy to process, but there are some problems.

Aberration

When a spherical lens is used, aberration inevitably occurs. Aberration is a phenomenon in which the image formation position of a ray of light passing through the center of the lens is different from that of a ray of light passing through the edge of the lens. Therefore, when the lens is used for imaging purposes, blurring and distortion will occur, making it difficult to obtain the desired image.

Multiple lenses are needed

In order to reduce this aberration, a combination of multiple spherical lenses is used in imaging applications. Aberrations are reduced by appropriately selecting and arranging the cross-sectional shapes ① to ⑥ described above, and optimizing parameters such as lens thickness, material, and radius of curvature of each sphere.

However, if only spherical lenses are used, the number of lenses increases, which takes up more space, makes the lens heavier, and costs more.

That’s where aspherical lens comes in.

＞＞What is an Aspherical Lens？About its Features and Benefits

Optical Design Technology Navigator will solve all your needs for spherical / aspherical lens!

TOYOTEC, operator of the Optical Design Technology Navigator, is an all-around optical manufacturer with proficiency in optical, mechanical, and electronical technology. We ca design and develop products from scratch based on our customers’ needs, and provides integrated support from design to productization. In addition to high-precision spherical lens processing, we are also capable of manufacturing even higher-precision aspherical lenses. In addition, we offer one-stop services from design to manufacturing of the entire lens unit, including peripheral parts, and not just the lens itself.

If you are thinking about something like, “If only there was a product like this…”, or, “Is it possible to do these kind of things with lenses?”, Optical Design Technology Navigator, a website operated by a group of optical design professionals, is the place to go. If you have any questions about optical design, please feel free to contact us at Optical Design Technology Navigator.

The post What Problems Do Spherical Lenses Have? appeared first on Toyotec Solutions.