Design Specifications

Want to make your own NeoLucida from one of our prisms? Here are some basic design parameters you should consider as you get started.

CAUTION! Before getting started:

  • The prisms are small, and they are glass, so take care when handling them. Wear gloves to prevent fingerprints.
  • Edges can chip, and glass surface can scratch easily. Work on a lintless cloth or soft work surface.
  • One side is coated with a protective black sealant. This protects the mirrored surface. The paint can scratch off, exposing your mirrored surface.
  • To clean your prisms, use a modest amount of glass cleaner on cotton swab or Q-tip.

NeoLucida Prism Design

The NeoLucida prism is a Right Angle Prism with a cross section of 90º-45º-45º. The glass is uncoated H-K9 glass. The hypotenuse is covered in a mirrored aluminum finish, protected by a black overpaint. The dimensions of the prism are 5mm x 5mm, with a 10mm extrusion length. As this is a square right triangle, the hypotenuse is approximately 7.07mm.

NL Prism Diagram 1080p



The prism works like this, where R1 is the first reflection and R2 is the second:

Berville Prism Diagram

When you look straight down at the prism edge, the exposed knife-edge splits your vision between the clear path to the paper below and a double-relfected image of the scene in front. Your brain interprets this as an overlap and you can then trace what you see.

You can make almost anything hold the prism in place, but keep these areas unobstructed for the required sight lines:

Berville Prism Diagram Design ParametersThe gray areas are “blindspots”, where you can safely build your prism holder without interrupting sight lines. Also note the exposed edge you look into: keep at least 1mm clear so the edge is clearly exposed. If your lower surface holding the prism extends past the prism edge, you will have trouble seeing the overlapping images.

The dark grey areas in this diagram loosely describe areas where you can “trap” the prism in place. By making a corner bracket at the top edge, you can secure the prism in place without adhesives.

NOTE: We DO NOT recommend using adhesives for the prism. Various chemical bonding agents can smear or leave residue on the uncoated glass, and/or corrode the black overpaint protecting your mirrored prism surface.