Strengthening Optical Design through Material Selection: Chalcogenide Glasses & Molded Plastics

Posted by The RPO Team on Jul 11, 2017 8:49:00 AM

In optics, manufacturability is heavily dependent on product design and material selection. Whether a product has a complex or simple design, the material used to create the lens will determine performance, cost, volume and several other factors. With a variety of materials and manufacturing methods available, how does a company determine the material that will provide the best outcome?

Early involvement from the design team is the best approach to deciding if a lens design is best suited for glass or plastic. Getting a design engineer's input prior to finalizing decisions ultimately saves time and money on a project because the physical assembly of the product effects selection.

Determining the Best Material for Your Optical Design

Major decision drivers in any material selection include:

  • Weight
  • Cost
  • Wavelength
  • Performance
  • Environment

Molded Plastic Optics

Because of significant advantages in weight and assembly, plastic optics delivers on high performance and unique capabilities. Molded plastic optics provide high-volume and tight tolerance solutions.

  • Typically have complex geometries and intricate features
  • No one plastic is ideal for every design
  • Important questions to ask when designing for plastics:
    • What type of durability will the lens require?
    • What does the piece have to do optically? What the performance goal for the optic?
    • What environment does the product have to exist in?
    • How will the plastic lens be integrated? Retaining rings, bonding, etc.


Chalcogenide Glasses

Demand for applications using night vision and thermal imaging has driven demand and cost for IR glass. Chalcogenide glasses are proving to be a high performing and cost-effective choice. If wavelengths fall in the infrared, consider the benefits of chalcogenides.

  • More moldable than standard materials
  • Offers optical benefits such as high index, low dispersion, and high transmission
  • Easily inserted into existing designs for customers
  • Wider range of spectral transmission offers greater design opportunities
  • SPDT is 4 weeks, molding in about 12 weeks
  • Cost – savings are greater because raw material cost of germanium and the scalability of molding
  • Volume – molding with chalcogenides allows for greater production volumes
  • Performance – powerful optical designs can come from using chalcogenides
  • Working with chalcogenides requires a specific clean room process to manipulate the toxicity of the material

RPO designs, prototypes and molds both glass and plastic optics, with extensive experience in IR lenses and lens assemblies. Our optical engineers can help you make material selections that meet your performance standards.

To learn more about working with IR materials, download our free guide:

Field Guide to Thermal Material Selection for Multiband IR Systems

Download Field Guide

Topics: Infrared, Molded Optics, Chalcogenides