Front Surface Mirror Utilization in the Display Industry

As we are in the second day of exhibition at SID 2010 (Society for Information Display) it seems appropriate that we should discuss the benefits of using a front surface mirror in the display industry.

Front surface mirrors are essentially regular mirrors with the exception that the reflective surface is in the front instead of in the back as you would find in your home bathroom mirror. The reason that this is done is to prevent image ghosting that occurs when an image is passed through the first surface of a pane of glass while reflecting about 10% of the light as it does so. A high percentage of the remaining 90% is reflected off the silver or aluminum coating on the back of the mirror and then about 10% of that is internally reflected off the front surface again and returned to the mirror coating only to reflect again toward the display. This ultimately can result in about 18% of the original emitted light ghosting unintended images a short distance from the original image on the display. Utilizing a front surface mirror removes this ghosting by presenting the original emitted image with a single surface off which to reflect.

Rear projection systems are typically the kind of display solution that utilizes a front surface mirror. One specific type of rear projection system that uses them more than others is one that implements a horizontal touch screen display acting as a table. This kind of display needs to sit about three to four feet off the ground, and that does not leave a lot of room for a projector to emit an image onto a large surface. In these situations the projector can be hung just below the surface of the touch screen display in an orientation that projects the image down at an angle where a front surface mirror will reflect the image back up to the table surface. This allows rear projection touch screen tables to remain fairly large without requiring a significant vertical space investment.

Another type of display that utilizes a front surface mirror is a virtual holographic display. These displays rely on a projector that is typically placed below the display area and oriented to project directly upward. As the image is projected upward it reflects off a unidirectional semi-transparent front surface mirror that is placed at an angle appropriate to direct the reflected image toward the viewer. Behind the mirror is placed an environment within which the virtual holographic image is to be viewed. The illuminated environment behind the mirror is clearly visible to the viewer and the projected image appears to float within or in front of the environment. Clarity in this kind of application is critical in order to create the illusion of the hologram.

Front surface mirrors are critical in these applications and using anything less would defeat the purpose of the application.

For more information about Sycamore’s Front Surface Mirror solutions, please call us (815.895.8533), email us or visit our booth at SID 2010 (booth 500).