Optical lenses are transparent materials used to refract light waves and control light beams. Two common types of optical lenses include cylinder lenses and acylinder lenses, and which one you should use depends on your application requirements. This article will cover the differences between cylinders and acylinders, including how they work, common applications, their benefits, and more to help you choose the best lens for your needs.
Cross-section image of a cylinder lens assembly
Cylinder lenses have different radii in the x and y axes, causing them to have a cylindrical or semi-cylindrical shape and allowing them to magnify images along only one axis. Their unique design focuses light to a one-dimensional line rather than a point. They can also be used to expand or condense light in one dimension.
At JML Optical, we use advanced CNC machining and X-Y axis polishing techniques along with metrology equipment to precisely engineer and produce cylindrical lenses and lens assemblies.
The primary function of cylinder lenses is to manipulate light based on the optical requirements of the application.
Many industries, such as industrial inspection, semiconductor manufacturing, entertainment, life sciences, and medical, rely on cylinder lenses for various applications, including:
Cylinder lenses offer a variety of unique advantages, including:
Ability to correct astigmatism
Capable of adjusting the height of an image
Compresses images into one dimension
Creates circular laser beams out of anamorphic (elliptical) laser beams
Acylinders, also known as aspherical cylinders, have a generally cylindrical shape but do not have a constant radius of curvature. Acylinders are to cylinders as aspheres are to spheres. Acylindrical lenses focus light along one axis. A properly designed and manufactured acylinder produces a diffraction-limited line focus.
At JML Optical, our highly trained opticians use state-of-the-art fabrication machines and metrology equipment to produce acylinder lenses for a variety of demanding beam-shaping applications for industries such as medical, industrial, scientific, and more. Common applications include:
To precisely control the shape of laser beams with the lowest possible levels of aberrations
To produce diffraction-limited line images or collimated beams – this means that if a lens is being limited by diffraction, it is as good as theoretically possible and cannot be improved upon
The benefits of acylinder lenses include:
High levels of efficiency
Reduced number of optimal components
Decreased weight of optical system
Sharpest possible line focus / collimation
Cylindrical and Acylindrical Lenses From JML Optical
Cylindrical and acylindrical lenses are used in various applications across diverse industries. At JML Optical, we fabricate our lenses using leading technology, machinery, and techniques to ensure precise, reliable lenses. As a leader in the design and volume manufacturing of lens assemblies and custom optics, we are capable of providing solutions that meet even your most challenging optical needs. For more information, or for help choosing the right lens for your application, contact our experts or request a quote today.
Optical assemblies play a critical role in the function of optical systems. As a result, they must be designed and engineered carefully to ensure they operate and perform as intended at an acceptable cost.
As optical assemblies can consist of a variety of optical components (e.g., lenses, mirrors, prisms, and filters) and mechanical mounting elements that must be aligned with great precision, some OEM instrument companies can find it difficult to design and engineer optical assemblies. Fortunately, an experienced and knowledgeable optical and optomechanical solutions provider can help navigate these stages to ensure the creation of a quality optical assembly suited for the intended application. Below, we highlight the key qualities to look for in an ideal partner.
1. Extensive Experience and Expertise
The solutions provider you partner with should have prior experience working on optical assembly projects for an industry and/or application similar to your own. This experience gives them the knowledge and skills needed to help you design and manufacture an optical assembly that meets your specifications and complies with industry/application-specific standards. Additionally, it can give them insight into the challenges and pitfalls faced in designing and manufacturing an optical assembly for your application or industry and the appropriate solutions to overcome and avoid them, which can translate to a better assembly design, shorter development cycle, and lower overall project costs.
Designing and developing complete optical system specs
Improving, producing, and evaluating a preliminary design concept or existing system
Optimizing the design for volume manufacturing approach
Designing optical components and mounting elements
Building and testing components and complete assemblies
2. Emphasis on Quality
The performance of an optical assembly hinges on the quality of the optical components and mechanical elements. For this reason, it is essential to partner with a solutions provider that is committed to meeting and maintaining high quality standards throughout the production process, from product design to final product testing. They should invest in robust quality control techniques and technologies to ensure product and process quality. Additionally, they should keep comprehensive documentation on QC processes to ensure they can provide proof upon request.
3. Knowledge of Performance-Cost Factors
When developing and manufacturing your optical assembly, it is important to find a balance between performance and cost. Your optical solution provider should be able to assist you with a performance-cost analysis to determine which designs and design elements are best suited for your performance requirements and project budget.
Some of the factors that influence the cost of the optical assembly include:
Number of components in the design
Optical performance and properties
Mounting and packaging requirements
Size and weight limitations
Fabrication and secondary service requirements
JML Optical: Your Partner and Expert for Optical Assembly Needs
While you may find it difficult to design and build an optical assembly, the right optical solutions provider can help you create one that meets your exact needs. At JML Optical, we have the knowledge, skills, and tools to develop and deliver custom optical and optomechanical solutions for a wide range of applications. By leveraging extensive experience and cutting-edge equipment, we carefully design, manufacture, and test assemblies to your specifications and standards.
An optical lens is a transparent glass material used to bend (refract) light waves and is used to guide, control, and focus light beams. They are designed and manufactured in a variety of shapes and sizes to meet the needs of a wide range of applications, from focusing, magnifying, and shaping light beams. There are many different types of lens: spherical, achromatic, Fresnel, aspheric and cylindrical, and the utility of each depends on the end application. In this article, an overview of cylindrical lenses and their use in different complex optical instruments and systems across multiple different applications.
Cylindrical lenses are more complex than their spherical counterparts. They feature one flat surface and one curved surface and rather than focusing light to a point, a cylindrical lens focuses incoming light rays into a one-dimensional line along a specific axis. Depending on the design of the curved surface, light can be condensed, focused, or expanded as needed for a given application and type of light source. At JML Optical, we have the engineering and optical design knowledge and expertise and manufacturing capabilities to supply precision, high-quality, custom cylindrical optics in a variety of formats and sizes to meet the highly demanding specifications of numerous industries, including industrialinspection, semiconductor metrology, life science imaging, and medical instruments.
CYLINDRICAL LENSES IN THE INDUSTRIAL MARKET
Numerous industrial applications benefit from the use of cylindrical lenses. Original equipment manufacturers (OEMs) of optical instruments are increasingly using laser technology for a variety of applications, from precision metrology tools to scanning systems for optical metrology.
Laser Scanning in Optical Metrology
Cross-section image of a cylinder lens assembly
Laser scanning is becoming an increasingly common means of obtaining component dimensions for product design and reverse engineering. Rather than depending on manual measurements and costly trial-and-error prototype testing, laser scanning are used to focused and direct laser beams at and across the surfaces of objects under inspection. Creating laser lines rather than laser spots is accomplished using cylindrical lenses and helps ensure more surface is covered in a single scan enabling accurate measurements, even in hard to reach areas.
Laser Alignment Tools
Laser alignment tools use cylinder lenses to focus laser lines to accurately measure parts and assemblies in production settings, from the positioning of parts on aircraft, cars and trucks. Accurate component alignment ensures the safe, efficient operation of vehicles and various types of industrial equipment and, through non-contact maintenance, can help extend the service life of equipment and minimize expensive field failures.
CYLINDRICAL LENSES IN THE SEMICONDUCTOR MARKET
Cylindrical lenses are used in a variety of precision inspection systems in the semiconductor industry. Two use cases are shared here; semiconductor wafer inspection and flat panel display manufacturing.
Semiconductor Wafer Inspection Tools
Isometric image of a cylinder lens assembly.
As next-generation chip technology continues to advance, the feature size of computer chips is becoming smaller and more complex. To ensure that semiconductor wafers are manufactured at high yield, they are subject to rigorous quality inspections using state-of-the-art optical tools equipped with lasers (as well as non-laser illumination sources) that are guided and controlled using large spherical, aspherical, and cylindrical lenses.
In one embodiment, in brightfeld/darkfield wafer inspection systems a cylindrical lens held in a rotating mount is used to control the angular orientation of the laser spot and ensures it is held in the correct position relative to the surface of the wafer when measurements are made. In a second example, cylindrical lenses are used to create extended, one-dimensional laser lines to scan across the surface of the wafer at high speed, ensuring greater surface area is imaged in a single scan to improve wafer throughout, repeatability, accurately in near continuous operation.
Flat Panel Display Manufacturing and Inspection Systems
Flat panel displays, such as liquid crystal displays (LCD) and active matrix organic light emitting diodes (AMOLED) used in smart devices and as TV screens, are complex display technologies that require multiple process steps to manufacture them in high volume and high yield.
Laser-based process technologies are critical in the production of advanced display technologies, where laser annealing and laser lift-off steps are used at different production stages to produce the final display. Cylindrical optics, along with other large flat optics, are used to expand, form, and create homogenized laser beams to enable larger areas to be processed in a given step. In such applications, large cylindrical optics with the highest surface qualities are crucial. In addition to display fabrication, expanded, homogenized laser beams are used in inspection tools and again, precision, large cylindrical lenses are used.
CYLINDRICAL LENSES IN LIFE SCIENCES
In the life sciences instrument market, cylindrical lenses are used in a variety of different applications. We describe two examples where precision cylindrical lenses make an impact: fluorescence microscopy and flow cytometry.
LIFE SCIENCE IMAGING: LIGHT SHEET FLUORESCENCE MICROSCOPY
Light sheet fluorescence microscopy (LSFM) is an advanced imaging platform that enables precision, volumetric (3D) imaging at high speed with high spatial resolution and high signal-to-noise. LSFM is used to help understand various biochemical process in real-time, including embryonic development and mobility measurements inside living Cells.
Flow cytometry is a technique used to detect and measure the physical and chemical properties of a population of cells or particles. The technique is routinely used in basic life science research, clinical diagnostics and, in specialized cases, used to detect contaminants in ultrapure water used in biopharmaceutical drug production. In one particular embodiment, spectral flow cytometry, two laser grade cylindrical lenses can be used to define a rectangular region rather than a focused laser spot, to spectroscopically interrogate the sample cells as they flow through a liquid stream. In cases where it is necessary to improve the quality of the one-dimensional beam, acylinders can be used to reduce the impact of aberrations and create more “clean” laser lines.
CYLINDRICAL LENSES IN ENTERTAINMENT (BROADCAST/CINEMA)
Professional motion picture camera and projection systems require high quality precision optical lenses and lens assemblies. The entertainment market demands robust housings, high-resolution image capture with low distortion over a large field-of-view (FOV), and effective and tough coatings to handle harsh, outdoor environments. Specialized cylinder lenses and lens assemblies are truly enabling optics used in this industry and enable high resolution, superior image quality and color contrast.
CYLINDRICAL LENS SOLUTIONS FROM JML OPTICAL
At JML Optical, we are committed to providing superior quality high-performance cylindrical lenses for an array of specialty applications, including industrial, semiconductor, medical, scientific, and the entertainment industry. We combine advanced CNC automated machining with traditional X-Y axis techniques to fabricate superior quality cylindrical lenses for our customers around the world.
The following article focuses on spherical and aspherical lenses, outlining their distinct properties, key benefits, and typical applications.
Spherical lenses—also sometimes referred to as singlets—are optical lenses that feature a spherical surface with a radius of curvature that is consistent across the entire lens. They are constructed such that the light entering them diverges or converges, depending on the lens design. Concave spherical lenses have a negative focal length that causes incident light to diverge (creating a virtual image). In contrast, convex spherical lenses have a positive focal length that causes incident light to converge (creating real and virtual images). The real images formed are highly focused, while the virtual images formed are highly magnified.
The main advantages of using spherical lenses in optical systems are their simpler surface design and lower manufacturing cost. These benefits make them suitable for various imaging applications in a diverse set of markets. Plano-convex lenses are often used in light collimation and monochromatic illumination operations that require infinite or near-infinite conjugate imaging properties. Plano-concave lenses are suitable for optical applications requiring the projection of light, the expansion of the light beam, or the expansion of the system’s focal length.
Aspherical lenses are optical lenses that feature a non-spherical, non-cylindrical shape that is rotationally symmetric. Unlike spherical lenses, they have a radius of curvature that varies from the center to the edge of the lens.
While the design and manufacture of aspherical lenses can be challenging, when constructed correctly, they can offer greater optical functionality than a comparable spherical lens. Some of the key benefits of using an aspherical lens in an optical application are:
Smaller number of elements required in an optical assembly
Reduced effects of spherical aberration, distortion, and marginal astigmatism
Larger aperture size
Improved light focusing and collection efficiency
For the above reasons, aspherical lenses are used in many imaging applications. They are commonly found in microscope imaging objectives and other image lens assemblies in life science instruments, semiconductor wafer inspection tools, medical devices, and defense and aerospace night vision imaging optics that rely on precision optical components.
Use in Imaging Applications
Both spherical and aspherical lenses find application in a wide range of imaging applications in a variety of end markets. They enable engineers, researchers, and scientists to use equipment—such as advanced microscopes, laser scanners, and other imaging devices—to make very precise measurements.
Some examples of the applications where spherical and aspheric lenses are found include:
Fluorescence microscope platforms: used by researchers to facilitate the identification and examination of specific sections of a specimen (e.g., decoding DNA sequences and imaging individual cells and tissue samples)
Cameras and laser-based ophthalmic tools for vision correction: used by trained clinicians and surgeons to diagnose and treat eye diseases and correct vision
Semiconductor wafer inspection tools: used by computer chip engineers to map defects and probe cards
Industrial laser machine tools: used by manufacturing companies to create and inspect products before, during, and after manufacturing
Night vision optics: used by frontline marines and soldiers operating under cover of darkness on critical defense missions
Optical Solutions at JML Optical
At JML Optical, we have designed and manufactured high-quality custom optical solutions for over 40 years. Our team has the knowledge and skills to develop and deliver spherical, plano, and aspherical glass lenses and complex lens assemblies suitable for some of the most demanding customer applications. In addition to our fabrication capabilities, we also offer the following services:
Manufacturability assistance and design performance
Lens assembly optimization
For additional information about our spherical and aspherical lens offerings, contact us today. To speak with one of our experts about an upcoming optical project, request a quote.
Equipment like optical microscopes, fluorescence readers and internal optical scopes are used across a wide variety of end test applications. For many of these instruments, precision optical components and optical assemblies are truly enabling and play a crucial role in creating, guiding and detecting light and producing meaningful data and images to aid clinical researchers, doctors and other healthcare practitioners in accurate and reliable critical care decisions for humans and animals.
As their utilization significantly affects the health and wellbeing of patients, optical-based technologies generally come with strict design requirements, such as compact and tight optomechanical tolerance design, high magnification with low image distortion for microscope-based instruments, as well and portability in point of care medical diagnostic applications. Additionally, many are subject to Federal Drug Administration regulations.
The following article offers insight into how these optical components and optical assemblies impact various life science and medical diagnostic applications, such as genomic analysis (e.g. fluorescence-based DNA sequencing), cell analysis (e.g. flow cytometry), microscopy analysis (e.g., tissue pathology), and hospital surgeries (e.g. surgical robotics) to name a few.
Fluorescence-Based Imaging and DNA Sequencing
Optical technologies have significantly improved the capacity of DNA sequencing. One process, known as optical DNA mapping (ODM), allows clinical researchers and medical experts to visualize long-range genome sequence information along single DNA molecules. By labeling (with fluorescent dye), stretching, and imaging individual DNA molecules, they create optical maps. The data gathered in these maps is then used to identify long-range structural variations, map epigenetic marks and DNA damage present across a genome and aid the DNA sequence assembly of complex genomes.
When used in such applications, optical technology opens up opportunities for clinical researchers to make crucial medical advancements to help understand and develop new treatments for a myriad of different diseases (e,g, cancer). A recent example of the power of fluorescence-based DNA analysis, researchers at Harvard Medical School, Boston Children’s Hospital, and the Broad Institute’s Stanley Center for Psychiatric Research used ODM to reach a genetic breakthrough crucial to the future treatment of schizophrenia.1 Similar discoveries may be in store regarding other medical diagnoses and treatments as the technology continues to develop.
Advanced Medical Diagnostic Imaging
Medical imaging technologies allow healthcare practitioners to create images of the human body to aid in diagnostic applications. The images captured range from macroscopic sections of the body such as internal organs and the skeletal system to microscopic segments, depending on the equipment employed.
As the field of image-based diagnostics expands, so too does the need for advanced optical technologies capable of peering inside the body. Important examples include whole-animal imaging in clinical research, where scientists use fluorescent markers to bind to tumors and use visible or near-infrared light to detect the location of the tumors for removal. A second example is image-guided fluorescence imaging (FIGS), an endoscope-based approach to identifying and removing cancerous tumors inside the patient, again using fluorescence-based detection. A third example is in the rapidly growing field of robot-assisted surgery, where a variety of optical modalities can be used in surgical procedures where the surgeon views the inside of the patient and controls robotic arms to remove malign tissue, such as cancerous tumors. In each application, precision optomechanical assemblies and components such as fluorescence filters are crucial and it is important to invest in quality, precision optics to ensure the accuracy and reliability of the procedure and the safety of the patient.
Microscopes have been central to physical examination applications for some time. Optical microscopes—the most common type employed—allow experienced health professionals to analyze and identify various specimens and chemical compounds to aid in patient diagnoses.
Microscopes have been at the heart of medical imaging applications for centuries, where images of cells and other biological samples were captured in reflection or transmission using white light. With the invention of the laser and advances in LED light source technology a myriad of imaging modalities are employed, including fluorescence imaging, Raman spectroscopy, and near- and mid-infrared (NIR, MIR) covering the ultraviolet to mid-IR wavelengths. An important example of the convergence of the old and new is the development of MIR microscopy for imaging slices of resected tumor masses in brain surgery to help surgeons identify tumor margins in real-time during surgery. Coherent Raman and fluorescence imaging approaches are also emerging as new optical weapons for daily surgical procedures. High transmission optics that perform repeatedly over several years are crucial to the acceptance of these microscopy methods as new tools in the operating room and beyond.
Optical Solutions From JML Optical
At JML Optical Industries, the medical technology market is one of our premier areas of expertise. Our extensive industry experience and application knowledge allow us to partner with medical OEM instrument developers from design to prototype to production, providing quality technical design expertise and precision, high-performance and long-lasting optical product solutions suitable for instruments used in clinical research laboratories as well as in industrial and medical pharmaceutical operations, and more.
We serve as a connection point between technology and biology. Our customers range from disruptive medical device start-up companies to large, global life science and medical equipment manufacturers, all of whom create products that impact the lives of people worldwide. The components and complete assemblies we supply help them achieve that goal and regularly find application in the following systems:
The glass types selected for an optical component or system can have a noticeable impact on price, lead time (both initially and on an on-going basis), manufacturing yield and performance.
In our experience of designing and manufacturing many thousands of custom optics over 40 years, customers come to us with designs that are optimized for performance but not always balanced by the impact on cost and delivery. The following are suggestions and things to think about to help you achieve that balance.
There are currently hundreds of different glass types available with prices ranging from $9 to more than $780 per pound. The percentage contribution of glass to the total cost of the optic varies.
In the case of a large optic that uses rare glasses, it can be 70% or more. Typically, the range is 20%-30%. In either case it’s a significant cost factor. And, that’s just the direct cost. There are also the indirect costs of manufacturing yield and availability.
SET A PRICE CAP
The leading optical design software packages (e.g. Zemax and Code V) offer a feature that allows you to set a “not to exceed” price when the software runs its glass selection routine. If you don’t like the resulting performance you can always raise the price cap.
By starting with the lower price glasses you’re more likely to find the sweet spot between performance and cost.
Use the glass manufacturer’s Melt Frequency-Relative Price Chart to manually create custom glass substitution catalogs in your lens design software program. The program will only use glasses from this list when evaluating alternate glass types.
CHECK OUT GLASS AVAILABILITY
Each of the major glass manufacturers (e.g. Schott and Ohara) publishes melt frequency data (see Ohara example) for their glass types. Consulting this information is important since the preference is to use more readily available glass types. This will shorten initial delivery as well as improve lead time for subsequent production.
An additional step is to call your optics vendor. They buy glass regularly and are in contact with the glass makers and their resellers on an on-going basis. They have a good sense of glass availability and, if in doubt, can get in touch with their glass source for more information.
AVOID (IF YOU CAN) GLASSES THAT STAIN EASILY
Some glass types are more susceptible to staining during manufacturing. Stains can result from environmental conditions in the manufacturing area (e.g. high humidity) or from the polishing compounds used to make the optic. Optics makers are constantly improving their manufacturing processes and environmental controls to minimize these impacts. However, you can help your project by selecting glass that has good environmental resistance characteristics.
There are only a few companies that make a full range of optical grade glasses. Schott, OHARA, CDGM, Pilkington, Hoya are the principle players. They each have their pluses and minuses with respect to breadth of product line, consistency across melts, delivery, availability and price (as much as 30%).
SPECIFY A GLASS MANUFACTURER AS A LAST RESORT
The major glass makers offer comparable product lines of glass types which means you have options. It will help your optics manufacturing vendor do their best work for you if you give them the choice of which glass maker to use. They can apply their experience and knowledge about optical glasses to your products and build flexibility into your program throughout its lifecycle. If there is a shortage or delivery delay from a given glass manufacturer, you may be able to avoid late deliveries to your customer by switching to the more available equivalent glass.
If you decide that you need to specify a glass manufacturer for your optic, it’s worthwhile to get your optics manufacturer’s recommendations. You’ll be better served by specifying a glass manufacturer that has the confidence of your optics maker.
DISPERSION AND INDEX OF REFRACTION TOLERANCES
Customer will sometimes request optics with index of refraction and/or dispersion tolerances that are tighter than standard, and beyond what the application requires. Often the tighter tolerances are boilerplate on the customer’s drawing. In order to achieve tighter tolerances, glass manufacturer’s do a post-production sorting. This translates to more cost and potentially limited availability. The standard tolerances offered by the major glass manufacturers are adequate for the large majority of applications.
Unless your tolerance analysis suggests that the design is sensitive to index of refraction or dispersion variations, you should be able to use glass with standard tolerances and get great results.
Standard Index of Refraction Tolerance (Nd) = 0.0005
Standard Dispersion Tolerance (Vd) = +/- 0.5%
The smaller the optic the less likely it is that it’s worth paying for a higher than standard homogeneity classification. Homogeneity is the variation in index across the glass blank. Since the rate of variation is small, the smaller the optic the less value there is in having a homogeneity certification. Essentially you’re paying to certify something that you are getting anyway.
RULE OF THUMB
We use the rule of thumb that an optic with a diameter less than 1” or 2” does not require higher homogeneity. Larger sizes are dependent on the application requirement.
The reasons size matters with respect to glass are twofold. First, the obvious – larger optics require more material resulting in a proportionately higher material bill. The other reason is based on the standard slab size of raw glass. Glass manufacturers produce raw glass in slabs. If your design requires an optic larger than the standard size will yield, the glass manufacturer needs to deviate from their normal manufacturing processes. This translates to higher cost, longer lead times and availability issues.
DESIGN TO STANDARD SIZES
If your application requires optics that clearly exceed the standard slab size, then it is what it is. If not, then it may be worth a few additional design iterations to see if you can get within that standard size.