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The roof or Amici prism deviates or deflects the image through an angle of 90 degrees. It is a right-angle prism whose hypotenuse has been replaced by a 90-degree TIR roof. Glass that does not contribute to the clear aperture has been trimmed away to reduce size and weight.
Optical glass such as K9, fused silica, sapphire, MgF2, silicon (Si), ZnSe, ZnS, etc. These materials possess high transmittance, low absorption, low scattering, uniform refractive index, and specific dispersion characteristics.
Precisely hemispherical. The machining precision of the center and radius of curvature of the sphere is extremely high.
The surface is precision polished to an optical grade of 10-5 to ensure image quality and reduce scattering and aberrations.
An AR coating is typically applied to the concave surface to maximize the transmittance of specific wavelengths of light (e.g. visible light) and reduce reflection loss.
Ecoptik China Roof Prism is made from N-BK7, an RoHS compliant version of BK7, and can be used when a right angle deflection of an image or laser beam is required. In passing through the prism, the image is both deflected right-to-left and top-to-bottom. The hypotenuse of the optical prism utilizes total internal reflection (TIR) to reflect the image through the prism. Polarization states may become rotated during reflection.
The roof or Amici prism deviates or deflects the image through an angle of 90 degrees. It is a right-angle prism whose hypotenuse has been replaced by a 90-degree TIR roof. Glass that does not contribute to the clear aperture has been trimmed away to reduce size and weight.
The roof prism refers to the type of the prism construct used in the binoculars. In the roof prism design, the alignment of the binoculars is done in a straight line. This makes these binoculars a little sleeker and more compact than their porro prism counterparts. These binoculars can be easily identified as the objective lenses line up to the eyepieces in a near-linear fashion.
Roof prism binoculars are technically more complicated than pro prism binoculars. The reason for this is that the prisms used in roof prism binoculars must be produced with exceptional care and they must also be of a higher quality than prisms used in Porro binoculars. Roof prisms also require top-quality coating.The advantage of binoculars with a roof prism is that they have straight tubes where the front or objective lens is in line with the rear or ocular lens, whereas binoculars with a Porro prism have tubes that are offset or not in alignment with each other. Roof prism binoculars are therefore more compact and easier to take along with you. It is also easier to seal them, making their internal lenses watertight and less susceptible to dust and damage.Scince the front objectives in roof prism binoculars are not out of alignment, as is the case with Porro binoculars, the perception of depth will be less than they would be with Porro binoculars.
| General spec. | High precision spec. | |
|---|---|---|
| Material | Optical glass (H-K9L, BK7, or others), Fused silica | |
| Dimension | 2mm~80mm | |
| Dimension tolerance | ±0.1mm | ±0.02mm |
| 90°Deviation tolerance | <3 arc min | < 3arc sec. |
| Surface flatness @ 633nm | λ/2 | λ/4 |
| Surface quality | 60-40 | 20-10 |
| Coating | Upon the customer's request | |
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