Best Laser Reader Scanner Window

Glass? Plastic? Which Plastic?

When building a product that involves displayed images and/or transmitted critical optical information, especially mobile computing units, you are faced with an important design decision: Which material is the best?

Lets first look at what features are important for an optimum functioning window:

Readability

High transmission in discrete wavelengths, low transmission in all others
Low reflectance
High optical clarity
Low distortion

Durability

Low susceptibility to break upon impact or when dropped
Scratch or mar resistant
Long usage life

Design flexibility

Ease of manufacture into more complex 2D geometries
Available in 3D shapes

Cost effectiveness

Inexpensive
Not volume sensitive

Glass vs. Plastic: How do they compare?

The following chart shows how we feel glass and various plastics compare on these
critical criteria:

	Glass	Cast Acrylic*	CR39	Polycarbonate*
Readability	very good excellent (w/ AR)	good/very good excellent (w/ AR**)	good/very good	fair (wavefront distortion)
Durability	poor (breakage)	fair (breakage) very good (scratches*)	fair (breakage) fair (scratches)	very good (breakage) poor (scratches) very good (hardcoated*)
Design flexibility	poor	very good (2D)	good	excellent (2D & 3D)
Cost effectiveness	very good (non AR) fair (w/ AR)	good/very good fair (w/ AR**)	good	good
* with TSP’s DURAVUE^® 1000 optically clear scratch resistant hardcoat with TSP’s DURAVUE^®** 7000 high resolution anti-reflective hardcoat

As you can see from the chart, while glass begins with slight advantages in readability and base cost, it is not suitable for most applications due to breakage, and also is too limiting for many of today’s more elaborate window designs/shapes. Of the optical plastics, cast acrylic and CR39 can deliver most if not all of the readability of glass, particularly when an anti-reflective coating like TSP’s DURAVUE^® 7000 is added. However, once you consider all four performance factors – readability, durability, design flexibility and cost – we believe nothing stacks up as well as optical grade cast acrylic with TSP’s DURAVUE^® 1000 scratch resistant hardcoat.

Before you select a material for your display or data acquisition window, we encourage you to talk to a TSP Sales Engineer to help you pick the option best for you. Contact us today!