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Key Takeaways: Telecentric lenses ensure consistent magnification and high image quality, minimizing distortion and offering a wide depth of field.  They excel in precise measurements across varying distances, crucial for quality control in industries like photolithography.  These lenses are pivotal for capturing detailed, clear images and detecting imperfections that conventional lenses might miss.  Whether for metrology or long-distance imaging, telecentric lenses provide unmatched reliability and performance in machine vision systems. Benefits of Telecentric Lenses Do you need repeatable, high-accuracy measurements? Then maybe you need to fit a telecentric lens to your machine vision system.   When viewed with a telecentric lens, an object will remain exactly the same size, no matter how  much it moves around. This is in contrast to more conventional lenses, for which close objects appear much bigger than those farther away. But how does this work, and what all are telecentric lenses good for? Let’s examine those two questions here. How Telecentric Lenses Work A telecentric lens is actually a multi-part optical lens assembly designed to eliminate parallax, or perspective error.  The figure below illustrates the difference between the field of view of a conventional lens and a telecentric lens: while a conventional lens has an angular field of view, the field of view of the telecentric lens is constant. This means that a telecentric lens has the same field of view  at any distance from the lens.  Key Advantages Advantages of telecentric lenses include: Constant magnification High image performance Low distortion Wide depth of field (depending on design of lens) Telecentric lenses have an important place in machine vision, especially when one might  need to take  measurements of objects that may be situated at different working distances from the lens. The set of images below illustrates this. Two identical  objects are placed at varying distances from the lens position. The first image shows what a conventional lens would see; the second shows the image taken by a telecentric lens. While a conventional lens might offer more useful information about how far away the object, the telecentric lens is what you would choose if you needed to make an accurate measurement under constant magnification.  Fixed Focal Length Lens Telecentric Lens Actual Setup A telecentric lens eliminates the parallax error caused by the angular field of view of a conventional lens. But telecentric lenses aren’t just used for measurements or metrology applications. They can also be used to enable long distance cameras to capture clear images, or for any applications where a sharp field of view and high resolution is crucial. They’re also used in photolithography.  Let’s look closer at a few specific applications here.    Telecentric Lenses in Quality Control Machine vision measurements and metrology is one application of telecentric lenses in quality control. But the unique properties of these lenses also enable them  to reliably find tiny defects that would be invisible to a more conventional lens. For these applications, teleentric lenses can be coupled with telecentric illumination systems.     The collimated rays of telecentric illumination enable a crisp, clear cut silhouette In telecentric illumination, light rays are collimated to be parallel to the optical access. This produces a clear silhouette. While diffuse reflections produce blurred edges when an image is taken with traditional lighting, telecentric illumination and imaging can produce images with sharp, high contrast edges. Thus a telecentric lens can be used to capture an extremely detailed, high resolution image, elucidating any defects in a manufactured part.    The image on the left shows the clear edge silhouette you can expect from telecentric lenses and illumination, in contrast with an image taken using a standard backlight. Telecentric lenses in Photolithography Microlithography is another important application of telecentric lenses. This manufacturing technique, often used for manufacturing integrated circuits, uses light to transfer enormous amounts of information to a wafer.  In typical photolithography,the wafer is coated by a light sensitive polymer (the photoresist), which is then exposed to patterned light and developed to form a three dimensional relief image. The exposure to light is achieved through projection printing, and the lithographic projection lens must maintain constant magnification throughout the depth of field. This requires a telecentric lens.   A schematic diagram of lithographic processing steps. Telecentric lenses are used to project patterned light in step 4. After a photoresist has been exposed, it undergoes further processing, culminating in a stripping of the remaining photoresist. The result is a precisely-manufactured part ready to perform the function for which it was designed.    Telecentric Lenses at Avantier At Avantier, we produce custom telecentric lenses for a wide variety of clients, in fields ranging from research to industry. Contact us if you’d like to discuss your optical needs or to set up a consultation.   Related Content

Key Takeaways Ruggedized imaging lenses are designed for harsh environments and are used in industrial, surveillance, military, and machine vision applications. Key considerations include environmental requirements (IP rating, temperature range, vibration, and shock resistance), optical specifications (focal length, aperture, coatings, and performance), and lens housing materials. Fixed magnification lenses, such as telecentric lenses and microscope objectives, offer high precision, while variable magnification lenses, like fixed focal length and zoom lenses, provide flexibility. Avantier’s ruggedized lenses are reliable, durable, and suitable for demanding applications. Ruggedized Imaging Lenses Ruggedized imaging lenses are specialized lenses designed with ruggedized construction. Therefore, imaging lenses represent a complex and nuanced element within imaging systems. These lenses are commonly used in demanding industrial, surveillance, security, military, and machine vision applications where standard lenses might fail due to exposure to harsh environments such as dust, high humidity, extreme temperatures, vibration, and mechanical shock. Microscope Objective Lens Telecentirc Lens Key considerations when designing ruggedized imaging lenses Environmental Requirements: IP Rating: Ensure the lens has a sufficient IP rating to protect against dust and moisture. Temperature Range: Ensure the lens can operate within the required temperature range. Vibration and shock: Ensure the lens can survive the vibration and shock without damage or affecting lens quality Optical Specifications: Focal Length: Ensure the lens meets focal length spec. Aperture: Fixed apertures are simpler and more robust. Thus, they are often preferred. Coatings: Anti-reflective, scratch-resistant, and hydrophobic coatings are beneficial for maintaining optical clarity and durability. Performance: ensure the as-built lens meets the resolution requirements Lens Housing: Housing Material: Metal housings are used for better durability. Aluminum housing is cheaper and less weight. Copper housing is non-magnetic.   Lens mount: ensure the lens meets the mechanical interface requirements Design Constraints  Budget Constraints: Consider the total budget and find the cost-effective solution for lens design and manufacturing. Mechanical Constraints: Consider the dimension requirements (e.g. total length, outer diameter), total mass, flange focal distance, etc.  Avantier offers a wide range of ruggedized lenses that are both reliable and budget-friendly, making them suitable for use in  industrial, security, and other demanding applications. Moreover, these lenses feature robust housings, fixed apertures, and anti-reflective coatings.  Advantages of using ruggedized imaging lenses Reliability: The moving parts are eliminated, and fewer moving parts mean less risk of mechanical failure. Durability: Enhanced resistance to environmental factors and physical stress. Consistency: Fixed aperture ensures stable imaging performance (resolution and depth of field), crucial for automated systems and long-term deployments. Types of Fixed Magnification Lenses Telecentric Lenses: Telecentric lenses are crucial for high-precision measurements within imaging systems. These lenses are specialized and come with advanced optical capabilities, making them ideal for applications requiring accuracy. Selecting a telecentric lens is often perceived as more challenging than choosing a fixed focal length lens. Learn more about Telecentric Lenses. Microscope Objectives: Microscope objectives are designed for imaging very small objects, often at magnifications exceeding 1X. These fixed magnification optics are optimized to function effectively at a specific Working Distance (WD), which is usually smaller compared to other imaging lenses. Learn more about Microscope Objective Lenses. Schematic Diagram of Microscope Objective Lens Types of Variable Magnification Lenses Fixed Focal Length Lenses: Fixed focal length lenses, also known as prime lenses, offer a specific magnification level and field of view without the ability to zoom. They are prized for their optical purity, often having fewer elements than zoom lenses, resulting in sharper, less distorted images. These lenses are ideal for situations where a high magnification or field of view is needed, such as in photography, videography, and various imaging applications where consistency and optical performance are paramount. Learn more about Fixed Focal Length Lenses. Zoom lenses: Fixed focal length lenses maintain a constant angle of view (AFOV), while zoom lenses can vary their focal length and, consequently, their AFOV. Zoom lenses offer unparalleled flexibility in applications where constant adjustments are needed, although they may not always provide the highest resolution. However, if the field of view (FOV) doesn’t need frequent adjustments during imaging, a fixed focal length lens is often the better option. In cases where changing FOV is necessary, stepper motors are employed to swiftly and precisely adjust the focal length. Learn more about Zoom lenses. Lens Layout The Importance of Ruggedized Imaging Lenses In conclusion, ruggedized imaging lenses are indispensable components in a wide array of industries and applications, providing unparalleled reliability, durability, and consistency in challenging environments. Avantier, with its wide range of ruggedized lenses that feature robust construction, fixed apertures, and advanced coatings, offers a cost-effective and dependable solution for demanding imaging needs. Whether it’s high-precision measurements with telecentric lenses, imaging small objects with microscope objectives, or the flexibility of zoom lenses, Avantier provides a comprehensive selection to meet diverse imaging requirements. By prioritizing key considerations such as environmental resilience, optical performance, and design constraints, Avantier ensures that ruggedized lenses deliver exceptional results, making us a trusted choice for industrial, security, and other critical imaging applications. Related Content