Overcoming the 2π ambiguity in low-coherence interferometric differential phase measurements

2001 ◽  
Author(s):  
Christoph K. Hitzenberger ◽  
Markus Sticker ◽  
Rainer Leitgeb ◽  
Harald Sattmann ◽  
Adolf F. Fercher
Keyword(s):  
Phase Measurements ◽  
Differential Phase ◽  
Low Coherence

Differential phase measurements in low-coherence interferometry without 2π ambiguity

2001 ◽  
Vol 26 (23) ◽  
pp. 1864 ◽  
Author(s):  
Christoph K. Hitzenberger ◽  
Markus Sticker ◽  
Rainer Leitgeb ◽  
Adolf F. Fercher
Keyword(s):  
Phase Measurements ◽  
Differential Phase ◽  
Low Coherence ◽  
Low Coherence Interferometry

A Comparative Study of Rainfall Retrievals Based on Specific Differential Phase Shifts at X- and S-Band Radar Frequencies

2006 ◽  
Vol 23 (7) ◽  
pp. 952-963 ◽  
Author(s):  
Sergey Y. Matrosov ◽  
Robert Cifelli ◽  
Patrick C. Kennedy ◽  
Steven W. Nesbitt ◽  
Steven A. Rutledge ◽  
...  
Keyword(s):  
Comparative Study ◽  
Radar Data ◽  
Drop Diameter ◽  
Horizontal Polarization ◽  
Differential Phase Shift ◽  
Phase Measurements ◽  
Differential Phase ◽  
X Band ◽  
Raindrop Size ◽  
Differential Reflectivity

Abstract A comparative study of the use of X- and S-band polarimetric radars for rainfall parameter retrievals is presented. The main advantage of X-band polarimetric measurements is the availability of reliable specific differential phase shift estimates, KDP, for lighter rainfalls when phase measurements at the S band are too noisy to produce usable KDP. Theoretical modeling with experimental raindrop size distributions indicates that due to some non-Rayleigh resonant effects, KDP values at a 3.2-cm wavelength (X band) are on average a factor of 3.7 greater than at 11 cm (S band), which is a somewhat larger difference than simple frequency scaling predicts. The non-Rayleigh effects also cause X-band horizontal polarization reflectivity, Zeh, and differential reflectivity, ZDR, to be larger than those at the S band. The differences between X- and S-band reflectivities can exceed measurement uncertainties for Zeh starting approximately at Zeh > 40 dBZ, and for ZDR when the mass-weighted drop diameter, Dm, exceeds about 2 mm. Simultaneous X- and S-band radar measurements of rainfall showed that consistent KDP estimates exceeding about 0.1° km−1 began to be possible at reflectivities greater than ∼26–30 dBZ while at the S band such estimates can generally be made if Zeh > ∼35–39 dBZ. Experimental radar data taken in light-to-moderate stratiform rainfalls with rain rates R in an interval from 2.5 to 15 mm h−1 showed availability of the KDP-based estimates of R for most of the data points at the X band while at the S band such estimates were available only for R greater than about 8–10 mm h−1. After correcting X-band differential reflectivity measurements for differential attenuation, ZDR measurements at both radar frequency bands were in good agreement with each other for Dm < 2 mm, which approximately corresponds to ZDR ≈ 1.6 dB. The ZDR-based retrievals of characteristic raindrop sizes also agreed well with in situ disdrometer measurements.

Optical phase measurements in red blood cells using low-coherence spectroscopy

2012 ◽  
Author(s):  
Itay Shock ◽  
Alexander Barbul ◽  
Pinhas Girshovitz ◽  
Uri Nevo ◽  
Rafi Korenstein ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Phase Measurements ◽  
Optical Phase ◽  
Low Coherence ◽  
Coherence Spectroscopy

An Application of Linear Programming to Polarimetric Radar Differential Phase Processing

2013 ◽  
Vol 30 (8) ◽  
pp. 1716-1729 ◽  
Author(s):  
Scott E. Giangrande ◽  
Robert McGraw ◽  
Lei Lei
Keyword(s):  
Linear Programming ◽  
Weather Radar ◽  
Polarimetric Radar ◽  
Phase Measurements ◽  
Physical Constraints ◽  
Differential Phase ◽  
Beam Geometry ◽  
Radar Systems ◽  
Linear Programming Methods ◽  
Consistency Results

Abstract Differential phase and its range derivative KDP are of interest to several hydrological applications from weather radar systems. Despite the attractive qualities of polarimetric differential phase measurements, the usefulness of these radar measurements is potentially undermined as a consequence of measurement fluctuations and physical or beam geometry artifacts. This paper presents an application of linear programming for physical retrievals, here designed to improve estimates of differential propagation phase by allowing realistic physical constraints of monotonicity and polarimetric radar self-consistency. Results of the linear programming methods to the phase-processing problem are demonstrated at several common weather radar wavelengths (10, 5, and 3 cm).

Picometer differential-phase measurements in the laboratory

2006 ◽  
Author(s):  
Gautam Vasisht ◽  
E. Robert Ligon ◽  
Erik E. Bloemhof ◽  
M. Mark Colavita
Keyword(s):  
Phase Measurements ◽  
Differential Phase

Differential phase measurements by partial coherence interferometry

1999 ◽  
Author(s):  
Christoph K. Hitzenberger ◽  
Angela Baumgartner ◽  
Harald Sattmann ◽  
Adolf F. Fercher
Keyword(s):  
Partial Coherence ◽  
Phase Measurements ◽  
Differential Phase ◽  
Partial Coherence Interferometry

Optical low-coherence reflectometer for differential phase measurement

2000 ◽  
Vol 25 (4) ◽  
pp. 227 ◽  
Author(s):  
Digant P. Davé ◽  
Thomas E. Milner
Keyword(s):  
Phase Measurement ◽  
Differential Phase ◽  
Low Coherence
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