Multiple aperture exit plate for field-widening a Fabry-Perot interferometer

Phase compensation of a separation scanned, all-sky imaging Fabry-Perot spectrometer for auroral studies

We describe a new all-sky imaging spectrometer using a separation scanned Fabry-Perot étalon. It is intended for ground-based mapping of upper atmospheric wind and temperature fields in the auroral zone. Its major advantage is that recorded spectra are not distorted by spatial and temporal brightness fluctuations in the aurora. We present a discussion of previous approaches to field widening a Fabry-Perot spectrometer, then describe the principles underlying our method. This enables comparisons with the throughput and the response to brightness fluctuations provided by previous instruments. We also describe our instrument's optical layout, its calibration, and data analysis.

Afocal coupled etalons: experimental confirmation of a high-resolution double-etalon modulator spectrometer

Experimental verification of the properties of a spectroscopic device consisting of two etalons coupled by an afocal system, and which behaves as a high-luminosity single-etalon single-aperture Fabry-Perot spectrometer, has been made. These preliminary results, limited by the available equipment, confirm the predicted theoretical properties of the double-etalon modulator device. As a corollary to this experimental verification, it has been found that successful operation of the device requires very close alignment of the optical axes of the etalons.

Afocal coupled etalons. DEM: a high-resolution doubleetalon modulator spectrometer

The properties of a spectroscopic device consisting of two etalons coupled by an afocal system, and which behaves as a high-luminosity single-etalon single-aperture Fabry-Perot spectrometer, have been investigated. Although the high-luminosity behavior is one of the many states in which a coupled dual-etalon system can exist, mainly the high-luminosity condition has been studied in detail here. This condition is reached when the orders of the etalons comprising the device are related by n(01) = n(02)eta(-2), where the coupling constant is defined as eta = micro(1)micro(-1)(2)f(1)f(-1)(2) micro(i) and f(i) are the indices of refraction and coupling lens focal length associated with the ith etalon. In high-luminosity conditions, one of the etalons serves as a multiple annuli mask for the other thus making it possible to use many of these annuli to achieve the desired high throughput. The limitation on the number of orders usable is given by the (small) nonlinearity in the matching of these orders, because of the different etalon gaps. The results of the study show that luminosity gains near 100 (when compared with a single-etalon single-aperture Fabry-Perot spectrometer) are possible at high resolving powers. This occurs when the coupling constant eta is not too far from unity. It is also shown that this device, or double-etalon modulator (DEM), is a compensated spectrometer since the gain increases with increasing resolving power. Other practical limitations, such as the beam walk-off from the edges of finite size etalons, are discussed.