Tag: Schmidt-Pechan

On the Passage of Linearly Polarized Light through an Uncoated Roof Prism

September 20, 2024

The famous Zeiss “paper” by Weruach and Dörband (translation attached below) on the development of phase coatings for roof prisms describes a simple test to determine if an optical instrument has coated prisms or not. They describe the use of two linear polarizers with the device placed in between; with phase coating present, one will … More On the Passage of Linearly Polarized Light through an Uncoated Roof Prism

The Physics of Roof Prism and Phase Coatings, Simplified: Polarization Effects

June 7, 2024

Many binoculars utilize roof prisms to keep the light along a single optical axis, making for a more compact shape. But the novel geometry of the prism’s reflecting surfaces creates a subtle interference effect which reduces the binocular’s resolution. The only way to mitigate this problem is to use specialized coatings on the roof surfaces. … More The Physics of Roof Prism and Phase Coatings, Simplified: Polarization Effects

The Physics of Roof Prisms and Phase Coatings, Simplified: Part III

August 18, 2023

Diffraction patterns and resolution In the previous post we traced the passage of light through an Amici roof prism, which required decomposing vectors into components, accounting for phase shifts upon reflection, and then looking at how the waves will be recombined. We can now see that there will be an opportunity for interference effects to … More The Physics of Roof Prisms and Phase Coatings, Simplified: Part III

The Physics of Roof Prisms and Phase Coatings, Simplified: Part II

August 18, 2023

Phase shifts and interference The previous post introduced the topic of roof prism performance loss resulting from phase shifts that accompany total internal reflection (TIR). These shifts are endemic to TIR and to any device that employs it, including not only roof but Porro prisms. But in the latter case, the shifts have no deleterious … More The Physics of Roof Prisms and Phase Coatings, Simplified: Part II

The Physics of Roof Prisms and Phase Coatings, Simplified: Part I

August 18, 2023

Introduction Some time ago, I began a fruitless search for a detailed treatment of the performance losses endemic to roof prisms, and the so-called “phase coatings” that rectify the problem. Optics manufacturers tout the advantages of their proprietary coatings, but provide few specifics regarding the effect that their technology solves, or how their solution works. … More The Physics of Roof Prisms and Phase Coatings, Simplified: Part I

The Physics of Roof Prisms and Phase Coatings

July 22, 2023

I’ve written a technical article on the topic of why the roof prisms used in binoculars require specialized coatings in order to improve their performance. I was prompted to pull this together because I couldn’t find a single reference that traced through this interesting problem in a non-trivial way. The article includes a derivation of … More The Physics of Roof Prisms and Phase Coatings