Objective lenses, essential in optical instruments, require aberration correction to optimize performance and influence field of view.
Objective lenses, essential in optical instruments, require aberration correction to optimize performance and influence field of view.
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
Key Takeaways Optical systems designed with meticulous attention to field of view parameters. Analysis tools utilized to ensure optimal field of view performance. Optimization techniques employed to meet specified field of view requirements effectively. Maximizing Optical System Performance with Zemax At Avantier, we use Zemax for designing, analyzing, and optimizing optical systems, such as lenses, objectives, cameras, and other optical devices. For optical system design, Zemax helps to construct a virtual optical system by defining optical specifications, such as surface curvatures, thickness, refractive indices, etc. For ray tracing, Zemax simulates the propagation of light rays through the optical system and helps evaluate the imaging performance of the system. For analysis, Zemax offers various analysis tools to evaluate, such as can calculate parameters like wavefront errors, MTF, etc. For optimization, Zemax has the capabilities to improve performance, such as Zemax can automatically adjust the variables (like lens positions, and curvatures) to find the optimal configuration that meets the desired criteria after specifying optimization goals. For tolerancing, Zemax allows performing tolerance analysis to assess the impact of manufacturing and alignment errors on system performance. Optical System RMS vs Field of view Challenges and Strategies in Optical System Design and Manufacturing Optical technology has become ubiquitous in modern applications, ranging from cameras and telescopes to medical devices and automotive sensors. Nevertheless, crafting these systems poses significant challenges for engineers, notably in rectifying optical flaws and meeting precise specifications. Correcting optical aberrations stands out as a formidable task in the realm of optical engineering. These aberrations, which cause image distortion or blurring, stem from factors like lens curvature, material properties, and refractive indices. Overcoming such imperfections demands a profound grasp of optics, sophisticated mathematical models, and advanced manufacturing methodologies. Addressing optical aberrations involves leveraging both geometrical optics and ray tracing techniques. While geometrical optics simplifies light behavior modeling within optical setups, ray tracing delves deeper, considering material refractive indices. The design journey to rectify optical aberrations entails meticulous steps. Engineers first establish imaging quality requisites, encompassing parameters such as focal length and field of view. They then utilize optical design software to generate initial designs, employing aberration theory to forecast expected flaws. Refinement of these designs hinges on a merit function—a mathematical tool assessing the variance between desired and actual imaging quality. Engineers iteratively adjust parameters until the system meets the predefined specifications. Attaining stringent tolerances represents another formidable aspect of optical engineering. These systems must adhere strictly to accuracy, precision, and repeatability criteria. Achieving such exactness necessitates specialized equipment and expertise across precision engineering, machining, and metrology domains. The optical manufacturing supply chain, intricate and global, spans multiple nations. Raw materials, including glass, plastics, and metals, are sourced globally. Manufacturing entails diverse processes like lens grinding, polishing, and surface coating with anti-reflective materials, culminating in optical system assembly. Future Trends and Innovations in Optical System Design and Manufacturing In conclusion, designing and manufacturing optical systems is a complex and challenging process. Correcting optical aberrations and achieving tight tolerances require a deep understanding of optics, advanced mathematical models, and sophisticated manufacturing techniques. As demand for optical systems continues to grow on a large scale, the supply chain and manufacturing industry will continue to evolve and improve to meet the demands of the market. RELATED CONTENT:
Key Takeaways Specializing in custom optics, Avantier employs Reverse Optical Engineering (Reverse Engineering) and advanced Manufacturing Capabilities. Non-destructive testing captures precise measurements of test samples. Processed data transforms into high-quality CAD models for analysis and optimization. Strict quality control ensures the accurate replication of components with a focus on meeting specific requirements. Advantages of Reverse Engineering in Creating Custom Optic Systems Reverse optical engineering, also known as reverse engineering in optics, is the process of taking an existing optical component or system, analyzing it, and replicating it to create a similar or improved product. This technique is useful when the original design is not available or when improvements need to be made to an existing product. One of the main benefits of reverse engineering is the ability to create a custom optic system that meets specific requirements. Optic systems are used in a variety of applications, such as medical devices, telecommunications, and military equipment. By reverse engineering an existing system, manufacturers can create custom optics that are tailored to their specific needs. Another benefit is the ability to replicate state-of-the-art optics designs. Optical components and systems can be complex, and creating a design from scratch can be time-consuming and costly. By reverse engineering an existing design, manufacturers can replicate the design more easily and cost-effectively, saving time and money in the process. Reverse Engineering Process Enhancing Optical Systems through Reverse Engineering Capabilities Reverse engineering also allows manufacturers to improve on existing optical systems. For example, they can analyze the design of an existing system and identify areas where improvements can be made, such as reducing chromatic aberration or improving the focal point. By making these improvements, manufacturers can create a more effective and efficient product. In terms of specific capabilities, reverse engineering can replicate a wide range of optical components and systems, including plano concave lenses, cylindrical lenses, and other types of lenses. Manufacturers can also choose from a variety of lens materials, depending on the specific requirements of their application. Reverse engineering relies on a unique set of manufacturing capabilities. One of the key capabilities is the ability to analyze and replicate the behavior of light rays as they pass through an optical system. This requires advanced knowledge of optics design and the ability to use specialized software and equipment. Manufacturing capabilities also include the ability to create complex optical components using a variety of techniques, such as diamond turning and injection molding. These techniques allow manufacturers to create precise components with high levels of accuracy and repeatability. In conclusion, reverse engineering is a valuable technique for creating custom optics and improving existing optical systems. It allows manufacturers to replicate state-of-the-art designs and make improvements to existing systems, resulting in more effective and efficient products. With a unique set of manufacturing capabilities, reverse engineering can replicate a wide range of optical components and systems, providing manufacturers with a cost-effective way to create custom optics that meet their specific requirements. What Avantier does – At Avantier, we specialize in providing comprehensive reverse engineering solutions for a wide range of industries. With our expertise in reverse engineering techniques and state-of-the-art technology, we offer a reliable and efficient process to recreate and analyze existing objects, components, or systems. Whether you need to replicate a discontinued part, enhance an existing design, or gain a deeper understanding of a product’s functionality, we have the knowledge and capabilities to assist you. What Avantier does in reversing engineering – Test samples: Once received the sample, our engineers will capture precise and detailed measurements of the object or component. This non-destructive process ensures that the original item remains unharmed while providing us with accurate digital data. Model Generation: The collected tested data is then processed and converted into a high-quality computer-aided design (CAD) model or optical drawing. Our skilled engineers utilize industry-leading software to create a drawing representation of the object, capturing its geometry, dimensions, and intricate details. Analysis and Optimization: Once the drawing is generated, we conduct a thorough analysis to understand the component/assembly design. This analysis enables us to identify areas for improvement, optimize the design, and suggest enhancements based on your specific requirements. Prototyping and Manufacturing: With the finalized model, we can proceed to the prototyping and manufacturing phase. Whether you need a functional prototype for testing or a fully manufactured component, we utilize advanced manufacturing technologies to deliver high-quality results. Quality Assurance: Throughout the reverse engineering process, we maintain strict quality control measures to ensure the accuracy and reliability of our work. We employ rigorous inspection methods and validation procedures to verify that the replicated component or system meets your specifications. Please contact us if you’d like to schedule a free consultation or request for quote on your next project. RELATED CONTENT
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:
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:
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:
Manufacturing optical components faces challenges in achieving full clear apertures meeting specifications.
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
Blurring is a significant source of image degradation in an imperfect imaging system. The optical system’s point spread function (PSF) describes the measure of blur in a given imaging system and is often used in image reconstruction or image recovery algorithms. Below in example of using inverse PSF to eliminate the barcode image degradation. Barcodes are found on many everyday consumer products. A typical 1-D (one-dimensional) barcode is a series of varying width vertical lines (called bars) and spaces. The example of the popular GS1-128 Symbology barcode is shown here: The signal amplitude of code image only has changes in horizontal direction (i.e. X-direction). For the imaging system used to capture and decode the barcode it is sufficient to look at one-dimensional intensity profile along the X-direction. In good conditions the profile may look like this: Using such a good scan, it is trivial to recover initial binary (only Black and only White) barcode. One can set threshold in the middle between maxima and minima of the received signal, and assign whatever is above the threshold to White, and below the threshold to Black. However, in situations when the Point Spread Function (PSF) of the imaging system is poor, it may be difficult or impossible to set the proper threshold. See example below: PSF is the impulse response of an imaging system, it contains information of the image formation, systematic aberrations and imperfections. To correctly decode barcode in such situations one may try to use inverse PSF information to improve the received signal. The idea is to deduce inverse PSF from the multiple signals obtained from the many scans of different barcodes of the same symbology. All barcodes of the same Symbology, such as GS1-128, have the same common features defined by the Symbology standards. This permits us to calculate inverse PSF coefficients by minimizing deviation of the received signals from the ideal barcode profile signals. A small number, such as 15, of the inverse PSF coefficients may be used to correct the received signals to make them as close to barcode signals as possible in the Least Squares sense. The inverse PSF coefficients were found and used to convert poor received signal shown previously into better signal shown on the next picture by red: While the recovered red signal is not ideal, it does permit to set threshold and correctly recover the scanned barcode.