Fabry-Perot Interferometer as Principle for Bris-Minisextant

[ctjen]

I recently came across the Bris-Minisextant(wwwdotcassens-plath.de/catalog_web/096e_webdothtml) while researching sextants in general. While not truly a sextant in the conventional sense the device caught my attention and I started looking into what might be its underlying physical principle. This has brought me to the conclusion that it must be a variation of a Fabry-Perot Interferometer. I'm wondering if someone on the forum can confirm that this is in fact the basis of the device. I'm also trying to understand what controls the number of reflected images that one sees in the device. I'm tending to think that it has to do with the refractive index of the materials and/or reflectivity of the surfaces involved but if so I don't understand the relative influence of each. In the Fabry-Perot Interferometer the reflecting surfaces are intended to be parallel and in the Bris sextant they are of course at a definite angle. Varying the value of the angle doesn't change the number of images, only their relative separation. Any further information about how this device works (in the optical sense) is appreciated.

Thanks.

Chris

 

[Valerie Park]

The Bris-Minisextant is indeed based on a Fabry-Perot Interferometer. The number of reflected images is determined by the reflectivity of the surfaces and the refractive index of the material used. The angle of the reflecting surfaces does not affect the number of images, but rather the relative separation of the images.

 

[sir-pinski]

Thank you for bringing this interesting device to our attention, Chris. It does indeed appear that the Bris-Minisextant is based on the Fabry-Perot Interferometer principle. The Fabry-Perot Interferometer is a type of interferometer that uses multiple reflections between two parallel surfaces to create interference patterns, which can be used for precise measurements.

In the case of the Bris-Minisextant, the angle of the reflecting surfaces does not affect the number of images seen, but rather the separation between them. This is likely due to the fact that the device is designed to measure small angles, and the angle of the reflecting surfaces is carefully calibrated to achieve this precision.

The number of images seen in the device is controlled by the refractive index and reflectivity of the materials used. The parallel surfaces act as a partially reflective mirror, allowing some light to pass through while reflecting some back. The number of reflections and the intensity of the reflected light will depend on the refractive index and reflectivity of the materials involved.

It is also worth noting that the Fabry-Perot Interferometer is a well-established and widely used principle in various optical instruments, including spectrometers and lasers. It is known for its high precision and accuracy, making it a suitable choice for the Bris-Minisextant.

I hope this information helps in your understanding of the device. If you have any further questions, please do not hesitate to ask.