月: 2022年12月

What Is a Junction Box?

A junction box is a device that collects electricity from solar panels and channels it to a power conditioner.

In solar panel arrays, each solar cell block is connected in series, and their output is gathered in the junction box via diodes to prevent backflow. The DC from the junction box is then converted to AC by the power conditioner.

Inside the junction box, each block connects to a switchgear device, which functions similarly to a distribution board breaker. This setup allows for the monitoring of electricity flow.

Uses of Junction Boxes

Junction boxes are essential in high-voltage power generation systems, particularly in aggregating electricity from photovoltaic systems.

While junction boxes are available for both indoor and outdoor installations. However, outdoor use is more common. Typically installed in protected areas from rain, like under roof sheds or on exterior walls for easy maintenance, outdoor junction boxes are waterproof and tend to be more expensive. Indoor installations, however, require extensive wiring from the solar panels through large openings in exterior walls.

Principle of Junction Box

A string in a solar panel setup refers to a single circuit created by connecting several solar panels’ positive and negative poles in series with PV cables.

Each string, which may comprise up to 20 solar panels, connects to a small breaker inside the junction box. Multiple strings can be wired to a single large breaker. The junction box consolidates multiple thin PV cables into one thick cable leading to the power conditioner. Without the junction box, connecting all PV cables directly in series to the power conditioner could lead to power loss due to voltage drop. Thin PV cables in a string are unsuitable for long-distance wiring.

Providing a small breaker for each string allows for targeted maintenance and part replacements, like solar panels, without shutting down the entire power system. To protect against equipment damage during lightning strikes, lightning protection elements are also incorporated.

Types of Junction Boxes

Junction boxes come in various types, such as plastic, metal, explosion-proof, and relay boxes with terminals.

1. Junction Box for VVF

These are specifically designed for VVF wires and are generally made of resin. They facilitate the piercing and connection of VVF wires.

2. Outlet Box/Pull Box

Commonly used in factories and outdoor settings, these junction boxes connect to thin steel, VE pipes, or other conduit pipes. They act as relay points where cables inside the box are connected, branched, and redirected through different conduits.

Drip-proof versions suitable for outdoor use are available, along with models featuring multiple terminals for easy wiring changes and branching.

3. Junction Boxes With Explosion-Proof Construction

Used with thick steel conduit pipes, these are designed for environments with flammable gases, like chemical plants and hazardous material storage facilities. They feature sealed construction to prevent ignition caused by electricity, robust structure, and packing-type cable glands for wire entry. All openings, including lids, are sealed with packing.

4. Round Exposed Box

A round exposed box, also known as a round box, is commonly used in remodeling and factory wiring. The body and lid are typically connected with screws at the top and bottom. Smaller than pull boxes and other types, they are used for smaller-scale wiring connections. The lower part of the box often has openings on all sides for drainage.

How to Select a Junction Box

Choosing the right junction box is critical to efficiently channel solar-generated power to the power conditioner without loss. Consider waterproofing, drip-proofing, voltage boosting, heat dissipation, and maximum input voltage. A highly functional junction box reduces energy loss but should match the system’s capacity without being excessive.

For example, a high maximum input voltage allows for designing a single block with high voltage, grouping more panels per block, reducing parallel connections, and minimizing power loss.

Structure of Junction Box

The typical junction box contains lightning protection elements, switchgear or circuit breakers, a terminal block for output, backflow prevention elements, and DC switchgear for input.

Lightning protection elements safeguard against strikes, while the switchgear, similar to a breaker, allows for current monitoring and maintenance. Some junction boxes integrate with power conditioners, eliminating the need for separate junction box installation. As they are generally outdoor installations, protection against rainwater and dust ingress is essential.

What Is a Flaw Detector?

Flaw detectors are non-destructive inspection devices used to detect the position, size, and shape of minute flaws in processed metals and materials that cannot be seen by the human eye.

Flaws in metals can accelerate the deterioration of products made of those metals and sometimes cause them to become defective, which is very dangerous.

The Flaw detector itself is about the size of a palm.

There are various types of Flaw detectors based on the principle of detection, with ultrasonic Flaw detectors being the most common.

Uses of Flaw Detectors

Flaw detectors are used in all kinds of manufacturing industries and workplaces where metal and concrete are used.

Cast iron (iron containing a few percent of carbon or silicon) is the most commonly inspected material, and is used in many heavy industrial products such as automobile parts.

Flaw detectors are also used to measure the length of anchor bolts that secure structures to concrete foundations, to detect the adhesion and delamination of metal and resin such as in the lining of pipes, and to check the water level of liquids inside containers that are difficult to open or close.

Principle of Flaw Detectors

Ultrasonic Flaw detectors can be broadly classified into three types: Pulse Reflection, Transmission, and Resonance.

In the pulse reflection method, a probe or transducer transmitting ultrasonic pulse waves, and when a part of the waves is reflected from a flaw or crack inside a metal, the echoes are displayed on the receiving screen to detect internal defects.

In the transmission method, an ultrasonic wave is emitted from one side of the inspection target by a transmitting probe and received by a receiving probe on the other side.

In the resonance method, ultrasonic waves are continuously emitted from the transmitting probe, and the presence of defects is detected by resonating the emitted and reflected waves.

Among these methods, the pulse reflection method is the most commonly used due to its high detection accuracy, and there are several types of pulse wave modes, such as perpendicular, oblique, surface wave, and plate wave.

What Is a Vibrator Motor?

A vibrator motor is a motor that produces vibration when activated.

Typically compact, these motors have built-in components and mechanisms to generate vibration. They are used in a range of devices such as smartphones, and game console controllers, and in machinery handling powder or granular materials to prevent stagnation. Vibrator motors, compared to air-driven vibrators, are notable for their ability to generate more significant vibration force.

Applications of Vibrator Motors

Vibrator motors find use in various fields. Below are some common applications:

1. Vibration Notification

A common use is in communication devices like cell phones and smartphones. They alert users to incoming messages or alarms through vibrations, offering a discreet alternative to sound. This is especially useful in environments where noise should be minimized, such as in meetings.

2. Touch Feedback

In touch screen devices, these motors provide tactile feedback when a button or icon is touched. This physical response aids in user interaction, enhancing feedback and touch confirmation during use.

3. Game Controllers

Game controllers for consoles and PCs often incorporate Vibrator motors. They enhance gaming experiences by producing vibrations in response to in-game actions and events, adding a layer of realism.

4. Industrial Equipment

In industrial settings, Vibrator Motors are used in equipment like hoppers. They prevent the “shelf hanging” of powder when it accumulates in a hopper, aiding in the smooth movement of materials. Vibrator motors are also used in vibratory mixers, devices that mix and homogenize materials through vibration.

Principle of Vibrator Motor

A vibrator motor includes an oscillator, or a weight, attached to its rotating shaft. The oscillator is designed with an offset center of gravity from the shaft connection. When the motor rotates, the eccentricity causes vibration, transferring it to the surrounding area.

The vibration amplitude depends on the oscillator’s mass and eccentricity, while the vibration frequency varies with the motor’s rotational speed. The selection of these characteristics is tailored to the motor’s intended application.

In portable devices, efficiency in generating vibration with minimal power, often from batteries, is crucial. For applications in material handling, setting the correct amplitude and frequency is vital. These settings may be theoretically derived or determined through trial-and-error testing.

Types of Vibrator Motors

Vibrator motors come in various designs, including coin type and cylindrical type.

1. Coin-Type Vibrator Motor

This type features a disk-shaped rotor and stator, resembling a coin. The rotor, usually made of magnetic material, vibrates when electrically activated, while the stator typically contains a coil.

Coin vibrator motors are small and thin, making them ideal for compact devices like smartphones. Their unique thin design minimizes the space needed for installation.

2. Cylindrical Vibrator Motor

Comprising a cylindrical rotor and surrounding coil, this type of motor allows for adjustable vibration intensity and frequency through current control. This flexibility makes them suitable for larger equipment and industrial machinery, as they can generate substantial vibration force and high frequencies.

What Is Capping Machinery?

Capping machinery is used to put caps and stoppers on bottles. Capping machinery can automatically and quickly press into the bottle, a task that is difficult to do manually. For soft materials such as PET bottles, the body of the bottle may be crushed by the stoppering process, and a neck holder is used to reinforce the bottle. There are different types of neck holders depending on the size and strength of the bottle.

There are a variety of products, from large capping machinery used in factories to simple manual capping machinery that can be used in small stores.

Uses of Capping Machinery

Capping machinery is used for filling and capping bottles with liquids. Since they can be used to stopper glass bottles, PET bottles, etc., they are used to stopper soy sauce, dressing caps, etc. They can also be used to stop ice cream cups. Other applications include ice cream cup lids. In the case of ice cream cups, the lid is often lightly tightened by the user to prevent the container from being crushed and then the manual capping machinery is used to ensure that the lid is securely fastened.

There are two types of screw caps: those with fins and those without fins, but most capping machinery can handle either type.

Principle of Capping Machinery

The principle of capping machinery is that the machine physically presses the cap or cork into the bottle from above. In some cases, the cap is tightened by turning it like a screw cap.

In most manual capping machinery, the user puts the lid on the bottle themself. When a switch or lever is pressed, the capping machinery comes down from above and corks the bottle. Those using a foot switch are safer because there is no risk of pinching the hand.

In automatic capping machinery, the machine does everything from putting the lid on. Some products combine a filling machine and capping machinery into a single unit. Depending on the type of lid or bottle, the height of the head and the speed at which the product flows are adjusted.

Various shapes of stoppers can be produced by changing the head. The variety of closures that can be corked includes cosmetics and food containers, beer crowns, wine corks, PET bottles, soy sauce, and dressing bottles, spouted pouches, and more. Capping machinery with an air cylinder can be used for corks with a pointed tip without crushing the tip.

What Is a Quick Freezing Freezer?

Quick freezing freezers are freezers that preserve food by freezing food rapidly.

Quick freezing refers to a technology that blows cold air below -30°C to freeze food within 30 minutes. It is applied to many foods in the food industry because it can freeze food while locking in flavor.

Among foods, it is suitable for freezing raw meat, seafood, and other foods with a firm tissue structure, and can preserve the quality of the ingredients without damaging them. On the other hand, foods with high water content are unsuitable for freezing because large ice crystals are formed during freezing. While slow freezing degrades food quality, quick freezing freezers can be used to preserve food quality to the maximum extent possible.

Uses of Quick Freezing Freezers

Quick freezing freezers are mainly used in the food industry but are also sold for home use. Specific uses of these freezers are as follows:

• High-end restaurants 
• Freezers for home use
• Food processing plants and food storage
• Frozen food for export and import

Quick freezing freezers are used in the food industry and culinary settings because they can store food without compromising quality. In some cases, coloring agents and preservatives are no longer needed.

Principle of Quick Freezing Freezers

A typical quick freezing freezer uses the same principle of freezing food as a household freezer. A refrigerant such as CFC is sealed inside the freezer, and the condensation of the refrigerant removes heat from the system.

However, in the case of quick freezing freezers, a strong blast of air at minus 30 degrees Celsius or lower is created and blown against the food. This lowers the air temperature below a temperature at which ice crystals form all at once, preventing the formation of large ice crystals.

Quick freezing freezers also use liquid nitrogen or other liquefied gas to freeze food. However, this is rarely employed because it requires liquefied gas filling. There is a risk of liquid nitrogen leaking and causing personal injury due to asphyxiation.

Other Information on Quick Freezing Freezers

1. Slow Freezing and Quick Freezing

Storing food in a frozen state is called cold storage. In particular, storing food at temperatures below -15°C is often referred to as freezing. There are two types of freezing: slow freezing and quick freezing.

The most common freezer freezing method is slow freezing. Larger ice crystals form due to the length of time required to go through the temperature range where ice crystals are formed. This destroys the food’s tissue and causes a loss of quality.

Quick freezing freezers, on the other hand, freeze quickly. The time required for ice crystals to pass through the temperature range in which they are formed is made as short as possible, resulting in rapid freezing. This prevents the formation of large ice crystals and maintains the high quality of the food without damaging its freshness or taste.

2. Small Quick Freezing Freezers

Some quick freezing freezers are small and reasonably priced. Most small quick freezing freezers can freeze 2 to 10 kg of food per hour. Uses of these freezers are utilized in restaurant kitchens to freeze and preserve food.

Even a small size can be used for quick freezing, and high freezing capacity can be achieved by improving heat transfer and other measures. Most of them are powered by three-phase 200 V. However, they can be used with single-phase 100 V. Products that can be used with single-phase 100 V are also available and can be selected according to the environment in which they will be installed.

What Is a Microspectrophotometer?

A microspectrophotometer is a spectrophotometer specialized for the measurement of very small amounts of samples.

Like the spectrophotometer, it is intended for quantitative analysis to determine the concentration of specific substances in a sample. It can analyze the amount of DNA, protein, and other substances contained in a sample, and is widely used in the life science field.

The instruments themselves are compact and easy to handle, and models with touch panels and models that can easily output data externally are also available.

Applications of Microspectrophotometers

The main application of microspectrophotometers is the determination of DNA, RNA, oligonucleic acids, and proteins from extremely small amounts of samples. They are mainly used in research and development in the life science field.

The quantification and purity evaluation of nucleic acids and proteins is a necessary process in genomic DNA preparation, RT-qPCR, and sample quality control. Kinetic evaluation is also performed by monitoring bacterial culture growth and measuring over time.

Principles of Microspectrophotometers

The basic principle of the microspectrophotometer is the same as that of the Spectrophotometer. The spectrophotometer quantifies the concentration of a particular substance in a sample based on how much light shined on the sample reaches through it. The higher the concentration, the lower the transmission because light is blocked by substances dissolved in the sample.

Structure of  Microspectrophotometers

A spectrophotometer is an instrument consisting of a light source, a sample cell (such as a sample port in the case of a microspectrophotometer), and a detector. The light emitted from the light source is divided into monochromatic light using a monochromator, irradiated onto the sample, and the light that passes through the sample (transmitted light) is measured using a detector.

A calibration curve of the amount of transmitted light (absorbance) and concentration is prepared using a solution of known concentration to determine the concentration of the unknown sample.

Types of Microspectrophotometers

Microspectrophotometers are generally capable of measuring very small sample volumes, but the minimum volume varies from instrument to instrument. For example, there are 0.3 µL, 0.5 µL, 1 µL, etc. It is important to select the appropriate one for the sample to be used.

On the other hand, some instruments can be used in a cell or on a cuvette board to measure samples of a certain volume. Some microspectrophotometers are also equipped with algorithms and programs to help perform advanced analyses.

For example, those equipped with programs that allow measurements over time at specific wavelengths are useful for performing kinetic analysis. Others are equipped with a reference library of spectra and impurity prediction algorithms that can predict impurities in a sample and calculate more accurate sample concentrations.

Other Information on Microspectrophotometers

1. Sample Handling for Microspectrophotometer

In an ordinary spectrophotometer, the sample is placed in a cell for measurement. In a microspectrophotometer, however, the sample is so small that it is generally dropped into the sample port with a pipette for measurement. Some instruments can be used for measurements other than micro amounts, and it is possible to analyze samples by placing them in a cell as in a regular microspectrophotometer, or by using a cuvette board.

In microspectrophotometers, it is often important that droplets are formed by surface tension, so each product has its mechanism to ensure proper measurement. Some instruments are also designed to confine the sample in a sealed space to reduce the risk of evaporation or contamination.

2. Light Source

Xenon flash lamps are often used as the light source. Xenon flash lamps are characterized by high brightness and low heat generation from the lamps. This reduces damage to samples that are sensitive to temperature changes.

What Is a Pulverizer?

Pulverizers are equipment that can grind and process fine particles down to a few micrometers in size.

By applying energy to a solid material of a certain size, the material is crushed into a fine powder. Depending on the size of the particles to be pulverized, the different stages of pulverization are distinguished as coarse and medium pulverization.

Since the properties of the powder vary depending on its particle size, it is important to select a pulverizer based on the uniformity of the particle size and the unit of milling.

There are various methods of adding energy to pulverizers, such as roller mills, jet mills, high-speed rotary mills, and container-driven mills.

Uses of Pulverizers

Pulverizers are used to reduce the substance to be processed to a powder form and a uniform particle size.

In industrial and other production settings, pulverization has the advantage of increasing the efficiency of the processing process by increasing the surface area of the individual solid particles as they become finer. It is also possible to finely grind materials that contain multiple components, making it possible to select and extract only the necessary components.

Examples of processed materials that can be finely milled include metals such as alumina and nickel, resins, chemicals, and pharmaceuticals.

Principle of Pulverizers

There are two types of pulverization: surface pulverization, in which the surface of a material is scraped by friction or other means to reduce it from fragments to smaller and smaller particles; and volumetric pulverization, in which the entire material is divided into larger and smaller particles by the application of force and gradually becomes smaller.

In practice, milling occurs when these two types of milling are combined. From the beginning, solid materials have small cracks or defects in their inner structure. When an external force is applied, it affects these partial defects and causes a major breakdown, leading to pulverization.

The mills can change the way energy is applied. Roller mills use gravity or centrifugal force of rollers to apply energy by pressing them against a rotating container, which compresses and crushes the material. In a jet mill, gas is injected at high pressure through a jet nozzle, and particles collide with each other in the jet stream to add energy and pulverize by friction and impact.

Types of Pulverizers

The following seven types of pulverizers are typical.

1. Roller Mill

Roller mills consist of several rollers whose gravity and centrifugal force press against a rotating table or bowl-shaped grinding vessel, compressing and pulverizing the sandwiched materials.

2. Jet Mill

Air, steam, or gas is jetted out from a nozzle at a pressure of several atmospheres or higher to accelerate the material particles, which are crushed by collision and impact.

3. Hammer Mill

A hammer rotating at high speed impinges on the feed particles to pulverize them. A perforated plate, screen, or grit is placed at the outlet to control the particle size of the milled product as a so-called screen mill.

4. Pin Mill

Dozens of pins are planted on the surfaces of two facing disks so that they engage each other. One or both disks are rotated at high speed to feed crushed material to the center of the disks, where it is crushed by the impact and shearing forces of the pins as it moves in a circumferential direction under centrifugal force.

5. Rotary Mill

A rotating cylinder with a horizontal axis is filled with a grinding medium (balls, rods, etc.) that fills 1/3 of its volume and crushes the material by rotating the cylinder.

6. Vibrating Mill

A cylindrical or trough-shaped mill is filled with balls or other grinding media.

7. Planetary Mill

The container filled with balls and crushed material is rotated by a mechanism in which the balls and crushed media rotate on their axis while the container orbits on its axis.

What Is Engraving Machinery?

Engraving machinery is a machine used to engrave letters or designs on glass, plastic, or metal.

They use rotating tools and lasers for quick and accurate processing. Some engraving machinery can be manually operated, while others can be connected to a computer for automatic processing.

Engraving tools include blades made of materials such as diamonds and lasers, and the appropriate tool is selected depending on the type of object to be processed. Engraving machinery is available in a wide range of sizes, from small tabletop machines to large machines, and can be selected according to the size of the object to be engraved.

Engraving machinery used to require a high level of skill developed by the craftsman handling the engraving machine, but with the development of processing technology for engraving machines, it is now possible to perform precision processing inexpensively and easily. Engraving machinery can be used to enhance the design and ornamentation of products and to create business cards, plates, trophies, and other items with beautiful and impressive engraved letters and designs.

Engraving machinery can also be used to create unique designs on products, which can enhance brand image and add value to products. Furthermore, Engraving machinery allows even mass-produced products to be easily and individually customized to meet the needs of the customer.

Uses for Engraving Machinery

Engraving machinery has a wide range of uses, from engraving letters and designs to three-dimensional engraving. The appropriate Engraving machinery can be selected according to the type and shape of the material to be processed to ensure high-precision processing.

For example, it is possible to engrave letters and designs on small parts such as jewelry, watches, automotive parts, and electronic devices. They are also used for architectural and building materials, signboards, and elegant ornaments.

In addition, three-dimensional engraving is possible on materials such as plastic and metal. For example, a variety of three-dimensional designs can be engraved, such as smooth curves on industrial products or emblems on automobile parts. Engraving machinery can also be used to create relief engraving, embossing, and unevenness.

In addition to metal and plastic, the machine can handle materials such as glass, wood, stone, and acrylic. They are also used in the manufacture of precision parts for medical devices, aerospace equipment, and semiconductors.

Principle of Engraving Machinery

Engraving machinery is based on two principles: motor and processing blades, and thermal processing using laser light.

1. Motor and Processing Blade

It consists of processing by making contact. Manual engraving machinery, which uses a motor and a processing blade, uses a rotating tool to shave the surface of the workpiece for engraving or cutting.

2. Laser Beam

Laser engraving machinery uses a laser beam to apply heat to partially melt the material to be engraved. Since friction and blade hardness are not required, a high degree of freedom of processing is possible.

By adjusting the intensity of the laser beam, the width of the engraving line can be varied freely. In addition, they are faster and more accurate than manual engraving machinery, and can easily process large quantities of work.

Types of Engraving Machinery

Engraving machinery is available in two main types: rotary and laser. Engraving machinery should be selected to suit the intended use.

1. Rotary Type

The rotary type is the most common engraving machinery. It uses a rotating tool to perform processing and is available in manual and automatic types. The manual type requires the skill of a craftsman, while the automatic type can be connected to a PC and automatically processed according to previously prepared data.

2. Laser Type

Laser-type engraving machinery is available. This method uses a laser beam to cut the surface of the material, and since it does not require friction or blade hardness, it is capable of high-precision processing. It also offers a high degree of freedom and can process detailed designs such as letters, logos, and photographs.

3. Others

Some types of engraving machinery are classified according to the size of the object to be engraved. A wide range of machines are available, from small table-top machines to large ones, which must be selected according to the intended use.

What Is a Tensiometer?

A tensiometer is a device that measures the tension of a belt, fiber, or rope. It is also called a tension meter.

Uses of Tensiometers

Tensiometers are used to measure the tension of a string-like object. Tension is the force of internal attraction that occurs when a material is pulled. Each material or product can withstand different tensile forces. If the tension is exceeded, the material cannot withstand the pull and may break, tearing fibers or breaking wires.

Tensiometers are used to measure the tensile strength of wires, ropes, and other products used for hanging applications. In particular, they are used to evaluate copper wire, winch ropes, and elevator wires, which are often used in a pulled state. Tension is a very important property in the evaluation of heavily loaded products.

Tensiometers are also useful in the evaluation of films and bundled ribbons. In these cases, besides being used to evaluate the durability of a product, they are also used to evaluate how much force a product can be pulled during a manufacturing process, such as winding.

Principles of Tensiometers

At its most basic, a tensiometer consists of a string supported at two points and pushed up or down at the center. The force to push up or down is measured as tension.

This type of tensiometer is highly portable and convenient, but it cannot measure the correct tension unless the object to be measured is properly pulled. Since the accuracy of measurement while being held by a human operator is affected by the operator’s body movements and other factors, it is preferable to use a tension meter fixed to a stand.

Pencil tension meters are used to measure the tension of belts used in various types of equipment. The pencil tension meter presses down on the center of the belt stretched between two pulleys, and the tension is calculated by subtracting the amount of belt deflection from the pressing force. Sonic belt tensiometers are also used to measure belt tension, in which a force is applied to the belt and bounced, and the sound waves generated by the belt are read and converted to tension.

Other Information on Tensiometers

1. How to Use a Pencil Tension Meter

This section describes how to measure the belt tension between two pulleys using a pencil tension gauge, the most popular and inexpensive type of tension gauge.

First, the span length is measured. The span length is the length between the centers of the two pulleys. Next, the amount of belt deflection is calculated based on the measured span length. For example, for a V-belt, the relationship between deflection (σ: mm) and span length (L: mm) is: deflection (σ: mm) = 0.016 × span length (L: mm).

Next, to measure the tension, a tensiometer is placed at the center of the span length and pressed down. The pencil tensiometer has a function to register the amount of deflection and subtract it, so the value displayed is the tension.

2. Reliability of the Tensiometer Application

Tensiometer apps have been developed for smartphones with functions similar to those of sonic belt tensiometers. For example, if a belt is under a certain amount of tension, such as a transmission belt in an automobile, it is possible to measure the tension with a smartphone tensiometer application.

The app can be used with V-belts, low-edge belts, timing belts, V-ribbed belts, and flat belts.

However, the accuracy of such a smartphone tensiometer application depends heavily on the sensitivity of the smartphone’s microphone, which measures the sound waves. A high microphone sensitivity increases accuracy, while a low microphone sensitivity decreases accuracy.

For this reason, the smartphone tensiometer application is not suitable for research, business, or other situations where highly accurate tensiometer measurements are required. As noted in the application’s usage notes, measurements taken with a smartphone tensiometer application should be considered as reference values only.

What Is an Interferometer?

An interferometer is a device that measures the surface shape, refractive index, size, etc. of an object by measuring the interference phenomenon that occurs when light is shone on the object.

The interference phenomenon is the superposition of multiple waves that strengthen or cancel each other to form a new waveform. It is most noticeable when the waves originate from the same wave source or have the same or close frequencies.

There are several types of interferometers, including Michelson interferometers, Mach-Zehnder interferometers, and Fizeau interferometers.

Uses of Interferometers

The main application of interferometers is the non-contact observation of object surfaces, including flat plates such as glass, metal, and ceramics. For example, glass-based applications include cover glass for smartphones and other devices, glass for LCDs, prisms used in color-resolved optics, and semiconductor mask substrates, while metal-based applications include molds and aluminum disks.

Other special items such as silicon wafers used in semiconductor devices for electronic equipment and hard disk substrates can also be measured. Radio interferometry is also a mechanism used in astronomical observations with radio telescopes.

Principle of Interferometers

Major interferometers split the light emitted from the light source into two beams, and one beam is transmitted through the sample and interferes with the other beam. The optical distance varies depending on the refractive index and distance of the transmitted sample, resulting in the appearance of a pattern of interference fringes.

By analyzing this pattern of interference fringes, the interferometer can measure the surface profile of the sample and the shape of the transmitted wavefront. The size of a sample that can be measured with an interferometer is a few to several dozen centimeters at the most. If the sample to be measured is large, it must be cut into pieces, etc.

Types of Interferometers

Interferometers are available that can measure polished surface planes such as glass planes, wafers, and mirrors, as well as spherical surfaces such as optical lenses, steel balls, and plastic lenses. There are also multi-axis interferometers that measure in two or three axes, and these multi-axis interferometers provide more sensitive measurements in a smaller space.

Laser scanning interferometers can also measure non-planar surfaces such as cylindrical surfaces. They are used to measure glass, fiber end faces, ceramics, ground metal surfaces, and plastics in injection-molded products. Various types of interferometers are available, so the choice should be made according to the application.

Other Information on Interferometers

1. Interference Phenomena

When multiple waves are superimposed, the amplitude of the new wave at a point coincides with the sum of the amplitudes of all the waves affecting that point. In this case, the waves strengthen each other where their phases match and weaken each other where their phases are reversed, which is called interference. An interferometer is a device to observe the state of an object by observing the interference fringes produced in this case.

2. Fizeau Interferometer

A Fizeau interferometer is an interferometer that uses a laser as its light source. The measurement mechanism is as follows.

1. The irradiated laser beam is transmitted through a diverging lens, a beam splitter, and a collimator lens, in that order, and becomes a collimated beam.
2. The light reaches a flat glass plate, which is the reference plate, and some of the light is reflected by the reference plane on the underside of the reference plate. The remaining light, on the other hand, is transmitted through the reference plate before reaching the sample to be measured and reflected.
3. The light reflected from the reference plane and the light reflected from the sample return to their original optical paths, and interference fringes are generated due to the difference in optical path length. The interference fringes are observed with a detector.

Fizeau interferometers are characterized by their simple configuration and high accuracy for plane and spherical measurements.

3. Analysis

Numerical analysis is performed using the obtained interference fringes. One of the typical methods is the Fourier transform.

By performing the Fourier transform, the frequency spectrum is extracted from the interference fringes. By inverse Fourier transforming the extracted spectrum, phase information of the measured material is obtained.