Optical Materials
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Syntec Optics uses a wide range of optical materials and processes to meet our customer’s needs and specifications. Syntec Optics offers the following services: optical, optomechanical, and electro-optical design services, optical and electronic assemblies for glass and plastics, single point diamond turning (SPDT), molded plastic optics (MPO), precision glass molding (PGM), thin-film coating, lithography, roll-to-roll printing, optical tooling (mold making), integrated photonics manufacturing (Si, Ge), and precision machining.
We have pioneered polymer optics that allowed plastic optics to replace glass optics as an effective, bio-compatible, and less expensive optics solution. Optical grade polymers exhibit properties that enable the high-quality performance of the optics. Here are descriptions of the various materials Syntec Optics uses in optical manufacturing.
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Acrylics ((Poly(methyl methacrylate) – PMMA)) (Refractive Index 1.491 @589nm) are available on the market by the trade names Plexiglas®, Acrylite®, Lucite®, and Perspex®. They offer excellent optical clarity, a high strength-to-weight ratio, and good mechanical properties. This optical polymer finds applications in lenses, medical components, sight gauges, light pipes, and light fixtures.
Polystyrene (Refractive Index 1.590 @589nm) is a transparent, rigid, and easy-to-mold thermoplastic. Identified with the trade name STYRON™, polystyrene offers good dimensional stability, processability, attractive light-transmission properties, chemical resistance, and radiation stability. It has applications in diagnostic medical optics components.
Polyetherimide (PEI) (Refractive Index 1.682 @589nm) is an amorphous engineering thermoplastic. It offers exceptional mechanical, thermal, optical, and electrical properties. It has a high glass transition temperature (Tg), making it a good choice for higher-temperature applications. This material can benefit medical, industrial, automotive, and electrical applications. `
Poly-Carbonate (PC) (Refractive Index 1.586 @589nm) offers more strength than plate glass and acrylic plastic. Polycarbonate (Trade name – Lexan) plastics possess impact resistance and transparency. PC internally transmits light almost as effectively as glass. These optical materials find uses in exterior lighting fixtures, medical devices, protective gear, and automotive components.
Methyl-pentene (Refractive Index 1.467 @589nm) (trade name TPX™) is a 4-methyl pentene-1-based olefin copolymer. Despite being a crystalline olefin polymer, it shows transparency. It provides good heat resistance and chemical resistance. It has the lowest density among thermoplastic polymers. It is used in windows for dynamic compression experiments, medical devices, and LED molds.
ABS (Acrylonitrile Butadiene Styrene) (Refractive Index 1.538 @589nm) is an opaque engineering thermoplastic. ABS (trade name Acrylon) consists of three monomers: acrylonitrile, butadiene, and styrene. With strong resistance to corrosive chemicals and physical impacts, it is very easy to machine and has a low melting temperature. It is suitable to use in injection molding manufacturing processes. ABS has wide applications in auto parts, consumer products, and electronic housing.
Cyclic Olefin Polymers (COPs) (Refractive Index 1.530 @589nm) are a new class of materials offering higher thermal stability and chemical resistance over standard polyolefins. COPs are increasingly popular as a substrate material for microfluidics. They are characterized by high chemical resistance, low water absorption, and good optical transparency in the near UV range. These are commercially available with trade names Apel, Arton, Topas, Zeonex, and Zeonor. Packaging, electronic, diagnostic, and optics applications are ideal for them.
Nylon (Refractive Index 1.535 @589nm) molding compounds offer crystal-clear transparency, excellent wear comfort, high durability, and improved processing capabilities. This unique property profile makes the high-performance polymer a preferred material for high-end lenses and visors.
NAS (Refractive Index 1.533–1.567 @589nm) transparent styrene-acrylic copolymers are strong, stiff, water-clear plastic with excellent thermal stability, better alcohol resistance, and less molded-in stress than acrylic. NAS applications range from medical devices to office accessories.
Styrene Acrylonitrile (SAN) (Refractive Index 1.567–1.571 @589nm) resin is a copolymer plastic commonly used in place of polystyrene because it has a better thermal resistance. SAN combines polystyrene’s clarity and rigidity with the hardness, strength, heat, and solvent polyacrylonitrile resistance. It enables applications for automotive parts, battery cases, kitchenware, appliances, furniture, and medical supplies.
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Syntec Optics’ patented nano-technology techniques – like HRDT (High Refraction Diamond Turning) for newly invented highly engineered resins – enable us to machine polymers like Acrylic, Polycarbonate, Nylon, Acetal, Polystyrene, Rexolite, Zeonex, Ultem, Topas, OKP4, and Teflon. We can also machine metals like Aluminum, Copper, Brass, and most non-ferrous metals. We also diamond-turn infrared crystals like Magnesium Fluoride, Calcium Fluoride, Germanium, Potassium Bromide, Zinc Sulfide, and Silver Chloride. Below is a table that summarizes the properties of materials suitable for HRDT and single-point diamond turning (SPDT).
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Low-Tg Glass
Optical, low Tg glass needs molding temperatures below 630 °C. It offers a range covering a refractive index of nd = 1.4 – 2.1 and a range of Abbe numbers from 18 to 95. Optical designers can utilize these properties to optimize their designs in the visible spectrum.
Chalcogenide Glass
We can manufacture infrared optics with high material efficiency from chalcogenide glass. Chalcogenide offers low molding temperatures below 400 °C, making it possible to use economical mold materials such as aluminum alloys and machining using single-point diamond turning.
Fused Silica
Fused Silica (quartz glass) shows an excellent transmission level with minimal internal absorption. Consequently, it has enormous potential for high-power optics. However, molding temperatures exceed 1000 °C. Manufacturing companies need to develop tools capable of withstanding extreme temperatures.
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Wordingham Technologies uses many materials to manufacture custom optical parts for our customers. Ultem ® combines excellent strength and stiffness with a low coefficient of linear thermal expansion while offering dimensional stability and extensive chemical resistance. Because of its low weight, it is suitable for medical or head-mounted optical applications. Invar also exhibits lower thermal expansion properties and is often used to require high-precision dimensional stability. Invar shows superior strength – ideal in manufacturing optical devices and metrology instruments.
| Material | Coefficient of linear thermal expansion (a) (10e-06 1/F°) | Density (g / M^ 3 ) |
| Aluminum | 12.3 | 2.7 |
| Brass | 10.4 | 8.7 |
| Copper | 9.3 | 8.9 |
| Stainless Steel | 8.1 | 7.4 |
| Steel | 6.7 | 7.8 |
| Titanium | 4.8 | 4.5 |
| Glass | 3.3 | 2.2 |
| Ultem ® | 1.1 | 1.5 |
| Invar | 0.9 | 8.0 |
Which manufacturing processes use optical materials?
Polymer molding, diamond turning, glass molding, precision machining, thin-film coating, lithography, and roll-to-roll printing
What are examples of optical materials?
Polymers – Acrylic, Polycarbonate, Nylon, Acetal, Polystyrene, Rexolite, Zeonex, Ultem, Topas, OKP4, and Teflon
Glass – Low-Tg Glass, Chalcogenide Glass, Fused Silica
Metals – Aluminum, Copper, Brass
Infrared Crystals – Magnesium Fluoride, Calcium Fluoride, Germanium, Potassium Bromide, Zinc Sulfide, and Silver Chloride
Gradient-Index (GRIN) Material