Proceedings, XXth congress: Proceedings, XXth congress

Altan, M. Orhan

Bibliographic data

Multivolume work

Persistent identifier:: 1663674213

Title:: Proceedings, XXth congress

Sub title:: Istanbul, 12 - 23 July 2004

Year of publication:: 2004

Place of publication:: Istanbul

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 1663674213

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist aus dem Copyrightjahr ermittelt.; Auch bezeichnet als XXth International Congress for Photogrammetry and Remote Sensing

Editor:: Altan, M. Orhan

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing, Commission Primary Data Acquisition

Document type:: Multivolume work

Volume

Persistent identifier:: 166368779X

Title:: Proceedings, XXth congress

Scope:: IV, 226 Seiten

Year of publication:: 2004

Place of publication:: Istanbul

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 166368779X

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(35,B8)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist aus dem Copyrightjahr ermittelt.

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Altan, M. Orhan

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 20., 2004, Istanbul; International Society for Photogrammetry and Remote Sensing

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: EARLY RESULTS FROM AN IMAGING INTERFEROMETER PROTOTYPE OPERATING IN THE SAGNAC CONFIGURATION Paolo Marcoionni

Document type:: Multivolume work

Structure type:: Chapter

International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B-YF. Istanbul 2004 5) apodization to avoid "Gibbs effect" (ringing); 6) inverse cosine transform application to retrieve at-sensor radiance spectrum. An ideal interferogram, therefore, is symmetric with respect to the zero path difference and contains cosine contributions only. However, a misaligned sampling grid, which doesn't match the region of zero path difference, results in an evident asymmetry in a real interferogram profile as it happens in Figures 7-8. The spectrum of the employed laser source has been retrieved (result of inverse cosine transform), and is plotted in Figure 9, where we have not adopted any apodization technique. 0.045 —0— Laser HeNe spectrum 0.035 0.025 0.015 Intensity (u.a.) 0.005 -0.005400 500 600 " 700 800 900 1000 Wavelenght (nm) Figure 9. Uncalibrated spectrum of radiance retrieved from the interferogram depicted in Figure 7. As already stated this type of interferometer needs neither a slit nor an aperture, leading to much larger flux of light available than that from traditional dispersive spectrometer. However, the resolving power of this system R=KÄ/max/Sk& is determined only by the number N of photosensitive elements of the detector array. This is the main reason that has led us to employ a 1024- elements array. Moreover, for a continuous spectrum, most of the radiation energy is concentrated in the central fringes of the interferogram but the physical information more relevant is distributed on the wings of the interferogram. Therefore, the detector needs a large dynamic range, which, in turns, determines the maximum variability of signal over the image. The spectral resolution seems to take great advantage from this experimental set-up. Due to the circumstance that the employed spectral source may be approximated to an impulse-like radiation field, the measurement above described is also a good test to estimate the instrument spectral resolution &k , which obeys the following law (Persky, 1995): ök = — | (7) 20PD max The obtained spectral resolution is about 175 cm (which corresponds to 7 nm at 632 nm) across the entire bandwidth. According to (4) the related maximum optical path difference is about 30 um. However, we believe this result could be improved because spectral resolution has been lost due to two main troubles which affected the shown data. The first one concerns with the circumstance that the Nyquist cut-off frequency of the input spectrum as filtered from the detector spectral sensitivity did not 134 match the available sampling frequency, thus generating aliasing in the blue side of the spectrum. The second trouble reason is related to the adopted optical configuration. We have verified that a different distance between the two folding mirrors can improve the obtained spectral resolution. In Figure 10 six frames of a brief sequence of measurements (images of the sky and landscape around Florence) are shown. Let us note how the scene details seem to move from left to right while the pattern of interference fringes remains fixed. i : IT p) m Figure 10. Six frames of a brief sequence of measurements (images of the sky and landscape around Florence city). As can be seen, the number of interference fringes is smaller than that obtained in previous laboratory measurements due to the poor coherence degree of the solar radiation. Data processing is currently under evaluation in order to retrieve physical properties from these images. 6. CONCLUDING REMARKS In this paper a new stationary imaging interferometer operating in the Sagnac configuration (developed at our laboratory) has been discussed. Experimental activity has been carried out in order to calibrate the instrument response and to measure its spectral resolution. Some problems connected to data processing methodology have been discussed regarding in particular dark-signal removal, DC offset compensation, inverse cosine transform routine implementation, and noise filtering.

Access restriction

Copyright

fullscreen: Proceedings, XXth congress (Part 8)

Multivolume work

Volume

Chapter

Table of contents

Cite and reuse

Volume

Chapter

Image

Image fragment

Citation links

Citation recommendation