What Are Optical Beam Splitters?
types of beam splitters, light beam, beamsplitter, beam splitter coating

Key Takeaways Beam splitters, essential for applications such as teleprompters and holograms, have different types that play a vital role in splitting light beams, while beam splitter coatings enhance optical surface properties, minimizing power loss and prolonging equipment lifespan. Common types include cube and plate beam splitters, polarized and non-polarized variants, and dichroic beam splitters. Their diverse applications underscore their significance in advancing technology. Exploring the Significance, Function, and Types of Beam Splitters A beam splitter is applied in various fields, from teleprompters to robotics. Without it, a lot of technology you know would not function. So, how does a beam splitter work? What are its types and applications? This article will cover what a beam splitter is, where it is applied, and the various types that exist. Beam splitter What is Beam Splitter? A beam splitter is any device that can guide light in two separate directions. The majority of these devices are constructed using glass cubes. Half of the light beam, when shone at the cube, passes through the glass, while the other half is reflected. They have been used in physics investigations to measure things like the speed of light. In real-world applications, they can be found in fiber optic telecommunications. This means that your high-speed internet connection might not function efficiently without them.  They are also utilized in optical devices such as microscopes, telescopes, cameras, and binoculars. Major Examples of the Usefulness of Beam Splitters Teleprompters Beam splitters are used in teleprompters, and these devices are an essential part of media. They help performers, politicians, YouTubers, and others read out scripts without losing eye contact.  This is especially important for those who struggle to remember their lines. With a teleprompter in play, the individual can focus on body language and delivery, which allows them to appear more confident and calm. The most vital part of a teleprompter is a piece of beam splitter glass. Putting a black shroud behind the glass makes it easier to read the writing. Also, you can show the writing on a tablet, phone, or laptop. Holograms Holograms and similar illusions are done using beam splitters. The light beam from the object bounces off the beam splitter, and the reference beam goes through it. To make a hologram, you must first use a beam splitter to separate the light from an object. For the picture in the mirror to stand out, you need a black background. Interferometry One of the most crucial applications of beam splitters is interferometry. A single beam is split in half, and one of the halves bounces off a surface. You may determine how far away something is by adding the light that returned to the initial beam, which helps to determine distance by generating interference patterns. Other Uses You can use beam splitters in several other fields, such as engineering, robotics, science, security cameras, smart mirrors, fiber optic, filmmaking, laser systems, and more.  Beam Splitter Coatings Beam splitter coatings are applied to optical surfaces to enhance light reflection, transmission, and polarization. Without coatings, some of the light that enters through the glass is lost, making the system less efficient. Metals and oxides are frequently employed to create thin films. You can find various beam splitter coatings composed of numerous materials and thicknesses used to provide the ideal balance of reflection and refraction. A good coating produces superior results and hides stains and scratches. If the beam splitters have a metallic coating, some of the light’s power will be lost during the reflecting process. On the other hand, If the beam splitters have a dielectric coating, the output power would be nearly equal to the input power. These films not only improve the performance of beam splitters but also safeguard the optical equipment’s surfaces. This will extend the lifespan of your beam splitter and all of its components. Common Types of Beam Splitters A Cube Beam Splitter A cube beam splitter is made by putting two triangle-shaped glass prisms on top of each other and gluing or resining them together.  In the 1800s, natural Canada balsam resin was the most popular glue. Today, epoxies and urethane resins made from chemicals are used more often.  The prisms can also be put together with a technique called optical contact bonding. This is a precise method that requires both surfaces to be clean. The manufacturer can change the resin layer thickness to change the ratio of power splitting for a certain wavelength. You can also add thin metal or dielectric coatings to split the beam based on its polarization or wavelength. A Plate Beam Splitter Plate beam splitters (dielectric mirrors) are thin pieces of optical glass with different coatings on each side. Most plates have an AR coating on the side that doesn’t face the light source to reduce Fresnel reflections. On the other hand, the side that faces the light source has an aluminum coating to act as a mirror. At a 45° angle of incidence, the mirror coating is put on plate beam splitters so that half of the light is reflected and the other half is let through. This is the classic 50/50 beam splitter and is the most common type of beam splitter. Plate beam splitters can also be made from IR materials like Calcium Fluoride (CaF2) and Potassium Bromide (KBr). KBr with a Germanium coating can be used for wavelengths up to 25μm, and CaF2 can be used for wavelengths up to 8μm.  The IR beam splitter is usually made as a plate and is meant to work as a device that transmits and reflects light in equal amounts. Most of the time, beam splitter coatings are put on the front, and AR coatings, like many other common plate designs, are put on the back. Non-Polarized Beam Splitters and How They Work Non-polarizing beam splitters divide light into an R/T ratio without changing its polarization.  In a 50/50 non-polarizing beam splitter, the P and S polarization states that are sent out and the P and

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Infrared Lenses: Features and Applications

Key Takeaways Infrared lenses (IR lenses), through opto-mechanical design, align components for high-performance optics and IR applications. IR lenses capture and focus radiation in various spectra. Used in medical, scientific, surveillance, and defense fields, they enable thermal imaging and spectroscopy, driving technological progress.  Opto-Mechanical Design for High-Performance Optics In order to ensure the seamless functioning of a high-performance optical system, it is essential to establish a foundation comprising suitable mechanical components that are well-maintained and accurately aligned. At Avantier, we have over 20 years of experience in opto-mechanical design. Our mechanical engineers play a key role in your projects by offering optimized and cost-effective designs. Except for optical software – Zemax, which we have talked about a little bit in other articles, our mechanical engineers will use software like AutoCAD, SolidWorks to work on the mechanical parts. The opto-mechanical design plays a crucial role in the overall process as it provides crucial support to the optics and maintains their performance. During this stage, we carefully integrate all interfaces and consider environmental factors such as vacuum conditions, extreme temperatures, vibrations, and more. By adhering to the specified requirements, we guarantee the system’s technical performance is upheld. Exploring the Applications and Features of Infrared Lenses Infrared lenses (IR lenses) are crucial components used in various industries for capturing and focusing infrared radiation. They play a vital role in enabling the detection and analysis of thermal energy emitted by objects. In this article, we will explore the features of IR lenses and their applications in medical instrumentation, life sciences, surveillance, and security and defense. IR lenses are designed to operate in different regions of the infrared spectrum, including short-wave infrared (SWIR), mid-wave infrared (MWIR), and long-wave infrared (LWIR). They are typically made from specialized materials such as germanium, zinc selenide, and chalcogenide glasses that are transparent to infrared radiation. Infrared Lenses Medical Instrumentation: In the field of medical instrumentation, infrared lenses find extensive use in thermal imaging and non-invasive diagnostics. They enable the detection of abnormal temperature patterns, aiding in the identification of diseases and injuries. Infrared thermal cameras equipped with MWIR or LWIR lenses can detect temperature variations on the skin’s surface, helping diagnose conditions such as inflammation, circulatory problems, and cancerous growth. Additionally, infrared lenses are utilized in endoscopic devices for minimally invasive procedures, enabling visualization and precise targeting of internal body parts. Life Sciences: IR lenses play a significant role in life sciences, particularly in infrared NIR spectroscopy and imaging applications. Infrared spectroscopy involves analyzing the interaction between infrared light and molecules, providing valuable information about their composition and structure. NIR spectroscopy, which operates in the near-infrared (NIR) region, is widely used for chemical analysis, pharmaceutical research, and food quality control. Infrared lenses enable the accurate focusing of NIR light onto samples and detectors, facilitating precise measurements and analysis. Surveillance: In the field of surveillance, IR lenses are utilized for night vision and thermal imaging. SWIR lenses enable enhanced visibility in low-light conditions by detecting light in the 0.9-1.7μm range. This allows for surveillance in complete darkness, making them ideal for military operations, law enforcement, and security applications. LWIR lenses, on the other hand, are employed in thermal cameras, which capture and analyze the heat emitted by objects. This capability is invaluable for perimeter security, detecting intruders, and monitoring critical infrastructure. Security and Defense: IR lenses have extensive applications in security and defense systems. MWIR and LWIR lenses are crucial components in infrared cameras used for long-range surveillance, target acquisition, and tracking. These lenses enable high-performance thermal imaging, allowing military personnel to detect and identify potential threats, even in challenging environments such as smoke, fog, and darkness. Additionally, SWIR imaging with infrared lenses aids in target recognition and identification by exploiting the reflected SWIR light from objects. InGaAs sensors are commonly used in conjunction with infrared lenses for imaging and detection in the SWIR region. They offer high quantum efficiency and sensitivity, making them suitable for low-light conditions. Infrared lenses facilitate the precise focusing of SWIR light onto InGaAs detectors, enabling clear and detailed imaging. Infrared Lenses in Diverse Applications In summary, IR lenses are essential components in various industries. They enable the capture, focusing, and analysis of infrared radiation in the SWIR, MWIR, and LWIR regions. Their applications span medical instrumentation, life sciences, surveillance, and security and defense. Infrared lenses play a crucial role in thermal imaging, night vision, spectroscopy, target recognition, and other critical functions, contributing to advancements in research, diagnostics, and security technologies. Please contact us if you’d like to schedule a free consultation or request for quote on your next project. RELATED CONTENT:

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Optical Filters: Longpass to Notch Spectrum
Optical Filters Longpass to Notch Spectrum, Neutral Density Filters

Key Takeaways Optical filters like Longpass, Shortpass, Bandpass, Multi-bandpass, Notch, and Neutral Density are essential for controlling wavelength ranges in diverse applications. The electromagnetic spectrum comprises Gamma rays, X rays, UV, visible light, IR, and radio waves. Human eyes perceive colors in visible light (380-780nm), while optical filters play a vital role in manipulating light for diverse purposes. Understanding the Electromagnetic Spectrum and Human Vision The electromagnetic spectrum encompasses a broad range of wavelengths, including Gamma rays, X rays, ultraviolet, visible light, infrared, and radio waves, arranged in order from shorter to longer wavelengths. Despite this extensive spectrum, our eyes are restricted to detecting visible light, which spans from 380 to 780nm in wavelength. Consequently, these variations in wavelength translate into visible light appearing as an array of distinct colors to the human eye. Visible Spectrum Exploring the Diversity of Optical Filters in Design and Manufacturing In the optical field, an optical filter stands out as one of the most prevalent components in design and manufacturing. The selective transmission of specific wavelengths and the blocking of unwanted light are accomplished through the utilization of optical filters. These filters, available in a variety of designs, include: Longpass filters, designed to transmit wavelengths above a specified value, exclusively allow longer wavelengths to pass while blocking shorter ones. Notably, these filters exhibit a sharp cut-on, gradually approaching zero transmission in the blocking range and nearing 100% transmission in the passband. Longpass Filter Shortpass filters, contrasting with longpass filters, exclusively permit the passage of shorter wavelengths while obstructing longer ones. In contrast, they exhibit a sharp cut-off, gradually approaching zero transmission from the high transmission end. Shortpass Filter Bandpass filters, in essence, can be seen as a fusion of longpass filters and shortpass filters. These filters exhibit high transmission within a specified wavelength range while effectively blocking all other wavelengths. Bandpass filter Multi-bandpass filters, can be regarded as duplication of bandpass filters, which have high transmission for multiple wavelength regions; Multi-bandpass Filter Notch filters, alternatively known as band stop filters, serve to obstruct a designated wavelength range while permitting the transmission of light on either side of that range. Notably, the shape of the curve on a wavelength–transmission chart resembles a V. Notch Filter Neutral density (ND) filters, conversely, serve to uniformly diminish the intensity of all wavelengths, ensuring the preservation of color integrity. Notably, a prevalent application of ND filters is discovered in photography. Once attached in front of the lens, an ND filter provides photographers with precise control over the light reaching the sensor. This empowerment enables photographers to finely adjust various specifications, thereby preventing overexposure and ultimately producing superior results in photos. Neutral Density Filter Typical Applications of Optical Filters Optical filters find extensive applications across various fields, encompassing photography, optical instruments, color lighting, astronomy, and fluorescence microscopy and spectroscopy. Illustratively, fluorescence filters enhance fluorescence microscopy systems. Additionally, laser line filters are employed in laser devices to prevent distortion and enhance image contrast. Raman filters play a crucial role in Raman spectroscopy, and machine vision filters are utilized in machine vision camera and sensor applications to enhance image contrast. RELATED CONTENT:

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Objective Lenses: A Guide to Aberration Correction

Key Takeaways Type of microscope objective lenses, such as Achromatic and Plan Apochromatic, are vital for imaging and address specific aberration correction needs. Corrections for cover glass thickness and working wavelengths are vital for optimal performance. Balancing magnification and resolution, alongside factors like working distance, ensures detailed observations. Critical Role of Objective Lenses in Microscopy In microscopes, objective lenses play a crucial role as the most complex and important component. These lenses, designed as multi-element lenses located closest to the specimen, receive light emitted by the specimen. Their primary function is to produce a real image, which is then transmitted to the eyepiece or computers. Widely employed in scientific research, biology, industry, and laboratory work, these lenses serve essential functions in various fields. Objective Lenses Types of Objective Lenses A diverse array of objective lenses, classified as types of objective lenses, is available for selection based on design and quality. The classification is generally determined by intended purpose, microscopy method, performance, magnification, and aberration correction. In this article, we will introduce the five types of objective lenses classified by aberration correction. Achromatic Objectives: These objective lenses, recognized as achromatic lenses, are not only widely used but also the most affordable. If no markings suggest otherwise, one can assume their achromatic nature. These lenses proficiently correct chromatic aberration in red and blue light, ensuring the convergence of these wavelengths at a single focal point, while also addressing spherical aberration in green light. Plan Achromatic Objectives (Achroplan): In a non-corrected objective, you can find sharp focus around the edges of the field of view or the center of the field of view. This type of microscope lens offers correction for chromatic aberration in two wavelengths and a correction of field curvature. Plan Fluorite Objectives (Plan Semi-Apochromats): These lenses were originally manufactured using the mineral fluorite, but now are mainly made of synthetic materials. These versatile lenses provide improved chromatic aberration correction and a flat field, with spherical aberration corrected for two wavelengths. Plan Apochromatic Objectives (Plan Apo): These lenses outperform Plan Fluorite Objectives by achieving superior transmission in the 400nm to 100nm range. They actively correct chromatic aberration for three colors (red, green, and blue), ensuring the convergence of these wavelengths at a single focal point. Furthermore, they actively correct spherical aberration for two or three wavelengths. Super Apochromatic Objectives: These lenses deliver outstanding performance over the entire visible to near-infrared field of view with axial color aberration. Objective Lenses Objective Lenses Key Specifications in Microscopy Aberration Correction or Resolution: Spherical and chromatic aberrations limit the resolution of conventional microscopes. Lenses with a high degree of aberration correction result in high-resolution images over the entire field of view. Magnification: Magnification refers to a microscope’s capacity to produce larger images, and high-magnification objectives offer detailed specimen images. Observers often confuse magnification with resolution, which defines an imaging system’s ability to reveal object detail. High magnification without adequate resolution may render small microbes visible but prevents distinguishing between microbes or sub-cellular parts. Avantier has dedicated years to design and manufacturing, ensuring simultaneous fulfillment of both magnification and resolution requirements. Numerical Aperture (NA): NA is the measure of its capability to gather light and to resolve fine specimen details at a fixed object. A lens with a high NA collects more light and can resolve finer specimen details at a fixed distance. Conjugate Distance: Objectives are corrected for a specific projection distance. In finite conjugate optical design, light from a non-infinite source is focused down to a point. In infinity-corrected optical systems, light emitted from the specimen passes through the objective lens and enters the tube lens as an infinity parallel beam, forming a real image. Cover Glass: Objectives are usually corrected for a specific cover glass thickness, with 0.17 millimeters being the standard. Immersion Media: The main purpose of using different types of immersion media is to minimize the refractive index between the objective and the sample. It is crucial to use the correct media, such as water, oil, or air/dry, as specified by the objective. Working Distance: The distance between the front end of the microscope objective and the surface of the specimen at which the sharpest focus is achieved. Proper positioning is important to obtain a good image at the specified magnification. Parfocal Length: The distance from the shoulder of the objective to the sample plane.  Working Wavelength(s): Objectives are corrected for specific wavelengths, with shorter wavelengths yielding higher resolution. RELATED CONTENT:

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Understanding Field of View (FOV) and Angular Field of View (AFOV) in Camera Lenses

Key Takeaways Field of View (FOV) in a camera lens, influenced by focal length and sensor size, captures the scene. Angular Field of View (AFOV), measured in degrees or length, is determined through optical tests. Shorter focal lengths intensify light convergence, affecting Angular FOV. Exploring the Field of View (FOV) in Camera Lenses The camera lens captures the extent of the observable area in a single shot, known as the Field of View (FOV). This encompasses what one can see through the eyes or an optical device. In photography, the FOV determines “what we are seeing in our image” and “how much of the scene we are seeing.” As light passes through the camera lens, it focuses on the subject being imaged by converging the light. Shorter focal lengths intensify the convergence of light to focus on the subject being imaged. Focal Length & Angle of View Guide Focal Lengths and Field of View (FOV) Dynamics Conversely, shorter focal lengths focus the image by converging the light more intensely. The determination of the focal length distance depends on how strongly the lens converges the light to focus the subject being imaged. This, in turn, affects the angle from the horizontal of the light captured by the lens. Referred to as the angular field of view (AFOV), it is necessary for determining the overall FOV. The FOV is expressed in either angular or size terms, with the former indicating the full angle in degrees and the latter denoting the length in millimeters or meters. Influences on Field of View (FOV) The lens focal length and sensor size influence the FOV, necessitating a wider FOV for a larger sensor if the lens focal length remains fixed. Typically measured horizontally due to the rectangular shape of sensors, FOV is usually expressed in millimeters. Optical tests commonly determine the FOV of UV, visible, and infrared cameras. These tests involve focusing light from a black body (an object that absorbs all light that falls on it) onto a test target at the focal place. A set of mirrors creates a virtual image at an infinitely far distance during the test. Camera FOV (or Camera Coverage) Field of View Formula Note: f is the lens focal length. Camera FOV vs. Lens FOV The image below shows the difference between the camera FOV and lens FOV. Camera FOV vs. Lens FOV Note: the maximum image (circle) diameter of the lens should be equal to or larger than the Sensor diagonal size. RELATED CONTENT

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How to Read an Optical Drawing

An optical drawing is a detailed plan that allows us to manufacture optical components according to a design and given specifications. When optical designers and engineers come up with a design, they condense it in an optical drawing that can be understood by manufacturers anywhere.  ISO 10110 is the most popular standard for optical drawing. It describes all optical parts in terms of tolerance and geometric dimension. The image below shows the standard format of an optical drawing. Notice thee main fields. The upper third, shown here in blue, is called the drawing field. Under this the green area is known as the table field, and below this the title field or, alternately, the title block (shown here in yellow). Once an optical drawing is completed, it will look something like this: Notice the three fields— the drawing field, the table field, and the title field. We’ll look at each of them in turn. Field I — Drawing Field The drawing field contains a sketch or schematic of the optical component or assembly. In the drawing here, we see key information on surface texture, lens thickness, and lens diameter. P3 means level 3 polished, and describes the surface texture. Surface texture tells us how close to a perfectly flat ideal plane our surface is, and how extensive are the deviations. 63 refers to the lens diameter, the physical measurement of the diameter of the front-most part of the lens 12 refers to the lens thickness, the distance along the optical axis between the two surfaces of the lens After reviewing the drawing field we know this is a polished bi-convex lens, and we know exactly how large and how thick it is. But there is more we need to know before we begin production. To find this additional information, we look at the table field. Field 2— Table Field In our example, the optical component has two optical surfaces, and table field is broken into three subfields. The left subfield refers to the specifications of the left surface, and the right subfield refers to the specifications of the right surface. The middle field refers to the specifications of the material. Surface Specifications: Sometimes designers will indicate “CC” or “CX” after radius of curvature, CC means concave, CX means convex. Material Specifications: 1/ : Bubbles and Inclusions Usually written as 1/AxB where A is the number of allowed bubbles or inclusions in lens B is the length of side of a square in units of mm 2/ : Homogeneity and Striae Usually written as 2/A;B where A is the class number for homogeneity B is the class for striae Field 3: Title Field The last field on an optical drawing is called the title field, and it is here that all the bookkeeping happens. The author of the drawing, the date it was drawn, and the project title will be listed here, along with applicable standards. Often there will also be room for an approval, for a revision count, and for the project company. A final crucial piece of information is the scale: is the drawing done in 1:1, or some other scale? Now you know how to read an optical drawing and where to find the information you’re looking for. If you have any other questions, feel free to contact us!

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Infrared (IR) Lenses

An IR lens is an optical lens designed to collimate, focus, or collect infrared light. At Avantier Inc., we produce high performance IR Optics such as IR lenses for use with near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MIR), and long-wave infrared (LWIR) spectra. These Infrared lenses can be customized for specific areas of the infrared spectrum, and are suitable for applications in defense, life science, medical, research, security, surveillance and other industries. Why Choose Avantier for Your Infrared Optics Needs Whether you require one-off production of single infrared (IR) lens assembly for a specialized research project or a large quantity of fixed-focus IR lenses for industry use, you need to know you can count on your provider. When you work with Avantier, you know you are getting the best product possible, at the best possible price. Our engineers design for manufacturability and work hard to ensure you get an optimized product at an optimal price and within an optimal time frame. That’s because we’ve done it, again and again. Our extensive experience in infrared optics enables us to both design and produce the highest quality lenses and assemblies for IR light. State of the art metrology and a robust quality control program means that every lens with the Avantier name on it will perform exactly as intended, and we check and double check that each component meets your full specification. Our manufacturing processes meet all applicable ISO and MIL standards, and our IR lenses are well known throughout the world. Types of Infrared Lenses Infrared light is classified as light between the wavelengths of 1 mm to about 700 nm. Infrared IR radiation can be further divided into several categories: The substrate chosen for a lens will depend partly on which IR region it is designed for. For instance, Calcium Fluoride  (CaF2) lenses are a good choice for radiation between 80 nm – 8 μm and so would be ideal for NIR SWIR wavelengths. Zinc Selenide has optimal transmission from 8 – 12μm, although it offers partial transmission over 0.45 μm to 21.5 μm  and  Zinc Sulfide (good transmission in 8-12µm,  or partial transmission from 0.35 to 14µm). Avantier and IR Lens Design Our experienced engineers and consultants can help you determine the best substrate and antireflective or reflective coating best fits your application. Every situation is unique, and we can help you find a cost effective solution that meets your need. Whether you need special resistance to mechanical and thermal shock, or good performance in rugged environments, we can select the perfect substrate for you.  We can also help design your IR lens or optical lens assembly. From basic lens selection (singlet, aspherical lens, spheric lens, cylindrical lens, custom shape lens) to design of aspheric lenses arranged in a complex opto-mechanical device, or any other infrared optical assembly, we have you covered. Avantier can provide lenses in chalcogenide material. Chalcogenide is an amorphous glass and is easier to process than traditional IR crystalline materials. Chalcogenide glass is an ideal material for both high performance infrared imaging systems and high volume commercial applications. Chalcogenide glass is available in a variety of chemical composition options, but BD6, composed of arsenic and selenium (As 40 Se 60), is the best choice in terms of cost and ease of production. Chalcogenide infrared glass materials and lenses are also an excellent alternative to expensive, commodity price-driven materials such as Ge, ZnSe, and ZnS2. Chalcogenide glass primarily transmits in the MWIR and LWIR wavelength bands, making it suitable for infrared imaging applications. Please contact us if you’d like to schedule a free consultation or request for a quote on your next project.

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Introduction to Microscopes and Objective Lenses

A microscope is an optical device designed to magnify the image of an object, enabling details indiscernible to the human eye to be differentiated. A microscope may project the image onto the human eye or onto a camera or video device.  Historically microscopes were simple devices composed of two elements. Like a magnifying glass today, they produced a larger image of an object placed within the field of view. Today, microscopes are usually complex assemblies that include an array of lenses, filters, polarizers, and beamsplitters. Illumination is arranged to provide enough light for a clear image, and sensors are used to ‘see’ the object. Although today’s microscopes are usually far more powerful than the microscopes used historically, they are used for much the same purpose: viewing objects that would otherwise be indiscernible to the human eye.  Here we’ll start with a basic compound microscope and go on to explore the components and function of larger more complex microscopes. We’ll also take an in-depth look at one of the key parts of a microscope, the objective lens. Compound Microscope: A Closer Look While a magnifying glass consists of just one lens element and can magnify any element placed within its focal length, a compound lens, by definition, contains multiple lens elements. A relay lens system is used to convey the image of the object to the eye or, in some cases, to camera and video sensors.  A basic compound microscope could consist of just two elements acting in relay, the objective and the eyepiece. The objective relays a real image to the eyepiece, while magnifying that image anywhere from 4-100x.  The eyepiece magnifies the real image received typically by another 10x, and conveys a virtual image to the sensor.  There are two major specifications for a microscope: the magnification power and the resolution. The magnification tells us how much larger the image is made to appear. The resolution tells us how far away two points must be to  be distinguishable. The smaller the resolution, the larger the resolving power of the microscope. The highest resolution you can get with a light microscope is 0.2 microns (0.2 microns), but this depends on the quality of both the objective and eyepiece. Both the objective lens and the eyepiece also contribute to the overall magnification of the system. If an objective lens magnifies the object by 10x and the eyepiece by 2x, the microscope will magnify the object by 20. If the microscope lens magnifies the object by 10x and the eyepiece by 10x, the microscope will magnify the object by 100x. This multiplicative relationship is the key to the power of microscopes, and the prime reason they perform so much better than simply magnifying glasses.  In modern microscopes, neither the eyepiece nor the microscope objective is a simple lens. Instead, a combination of carefully chosen optical components work together to create a high quality magnified image. A basic compound microscope can magnify up to about 1000x. If you need higher magnification, you may wish to use an electron microscope, which can magnify up to a million times.  Microscope Eyepieces The eyepiece or ocular lens is the part of the microscope closest to your eye when you bend over to look at a specimen. An eyepiece usually consists of two lenses: a field lens and an eye lens. If a larger field of view is required, a more complex eyepiece  that increases the field of view can be used instead.  Microscope Objective Microscope objective lenses are typically the most complex part of a microscope.  Most microscopes will have three or four objectives lenses, mounted on a turntable for ease of use. A scanning objective lens will provide 4x magnification,  a low power magnification lens will provide magnification of 10x, and a high power objective offers 40x magnification. For high magnification, you will need to use oil immersion objectives. These can provide up to 50x, 60x, or 100x magnification and increase the resolving power of the microscope, but they cannot be used on live specimens. An microscope objective  may be either reflective or refractive. It may also be either finite conjugate or infinite conjugate.   Refractive Objectives Refractive objectives are so-called because the elements bend or refract light as it passes through the system. They are well suited to machine vision applications, as they can provide high resolution imaging of very small objects or ultra fine details. Each element within a refractive element is typically coated with an anti-reflective coating. A basic achromatic objective is a refractive objective that consists of just an achromatic lens and a meniscus lens, mounted within appropriate housing. The design is meant to limit the effects of chromatic and spherical aberration  as they bring two wavelengths of light to focus in the same plane. Plan Apochromat objectives can be much more complex with up to fifteen elements. They can be quite expensive, as would be expected from their complexity. Reflective Objectives A reflective objective works by reflecting light rather than bending it. Primary and secondary mirror systems both magnify and relay the image of the object being studied. While reflective objectives are not as widely used as refractive objectives, they offer many benefits. They can work deeper in the UV or IR spectral regions, and they are not plagued with the same aberrations as refractive objectives. As a result, they tend to offer better resolving power.  Microscope Illumination  Most microscopes rely on background illumination such as daylight or a lightbulb rather than a dedicated light source. In brightfield illumination (also known as Koehler illumination), two convex lenses, a collector lens and a condenser lens,  are placed so as to saturate the specimen with external light admitted into the microscope from behind. This provides a bright, even, steady light throughout the system.  Key Microscope Objective Lens Terminology There are some important specifications and terminology you’ll want to be aware of when designing a microscope or ordering microscope objectives. Here is a list of key terminology. Numerical Aperture Numerical aperture NA denotes

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Lossless Image Compression Example

For storage and transmission of large image files it is desirable to reduce the file size. For consumer-grade images this is achieved by lossy image compression when image details not very noticeable to humans are discarded. However, for scientific images discarding any image details may not be acceptable. Still, all the images, except completely random ones, do include some redundancy. This permits lossless compression which does decrease image file size while preserving all the image details. The simplest file compression can be achieved by using well-known arithmetic encoding of the image data. Arithmetic encoding compression degree can be calculated using Shannon entropy, which is just minus averaged base 2 Log of probabilities of all the values taken by the image pixels. This Shannon entropy gives averaged number of bits per pixel which is necessary to arithmetically encode the image. If, say, the original image is a monochrome one with 8 bits per pixels, then for completely random image the entropy will be equal to 8. For non-random images the entropy will be less than 8. Let’s consider simple example of NASA infrared image of the Earth, shown here using false color This image is 8-bit monochrome one, and has entropy of 5.85. This means arithmetic encoding can decrease image file size 1.367 times. This is better than nothing but not great. Significant improvement can be achieved by transforming the image. If we would use standard Lossless Wavelet compression (LWT), after one step of the LWT the initial image will be transformed into 4 smaller ones: 3 of these 4 smaller images contain only low pixel values which are not visible on the picture above. Zooming on them saturates top left corner, but makes small details near other corners visible (notice the changed scale on the right): Now the entropy of the top left corner 5.85, which is close to the entropy 5.87 of the complete initial image. The entropies of the other 3 corners are 1.83, 1.82 and 2.82. So, after only one LWT step the lossless compression ratio would be 2.6, which is significantly better than 1.367. Our proprietary adaptive prediction lossless compression algorithm shows small prediction residue for the complete image: Actual lossless compression ratio achieved here is about 4.06. It is remarkable that while the last picture looks quite different from the original NASA image, it does contain all the information necessary to completely recover the initial image. Due to lossless nature of the compression, the last picture, using arithmetic encoding, can be saved to the file 4.06 times smaller than the initial NASA picture file. Our proprietary algorithm applied to this smaller file completely recovers the initial picture, accurately to the last bit. No bit left behind.

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