Nulling at TNO TPD: Status update

TNO TPD has an extensive experience in the realisation of highly stable passive and active opto-mechanical systems. Future missions of ESA like DARWIN [1] rely heavily on these systems such as metrology equipment, delay lines, nulling equipment etc.. The nulling equipment will be used in the Nulling mode of DARWIN in which it will detect Earth...

River dike deformation measurement with airborne SAR

Due to extremely high water levels or extremely dry periods, river dikes can deform and eventually burst. The deformation can be measured with repeat-pass synthetic aperture radar (SAR) interferometry. Two flights (5.5-day interval) with an airborne C-band SAR were carried out to verify a particular case. During the second flight, the dike was...

Absolute distance metrology for space interferometers

Space interferometers consisting of several free flying telescopes, such as the planned Darwin mission, require a complex metrology system to make all the components operate as a single instrument. This metrology system consists of various sub-systems to monitor distances, angles and speeds. Our research focuses on one of these sub-systems that...

The design of a breadboard cryogenic optical delay line for DARWIN

TNO TPD, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has designed a compact breadboard cryogenic delay line for use in future space interferometry missions. The work is performed under ESA contract in preparation for the DARWIN mission. The breadboard (BB) delay line is representative of a flight mechanism, with all...

Advanced optical delay line demonstrator

TNO TPD, in cooperation with Micromega-Dynamics and Dutch Space, has designed an advanced Optical Delay Line (ODL) for use in future ground based and space interferometry missions. The work is performed under NIVR contract in preparation for GENIE and DARWIN. Using the ESO PRIMA DDL requirements as a baseline, the delay line can be used for...

Magnetic bearing optical delay line

TNO TPD, in close cooperation with Micromega-Dynamics and Dutch Space, has developed an advanced Optical Delay Line (ODL) for use in PRIMA, GENIE and other ground based interferometers. The delay line design is modular and flexible, which makes scaling for other applications a relatively easy task. The developed technology can also be applied in...

Delft Testbed Interferometer: a homothetic mapping test setup

The Delft Testbed Interferometer (DTI) will be presented. The basics of homothetic mapping will be explained together with the method of fulfilling the requirements as chosen in the DTI setup. The optical layout incorporates a novel tracking concept enabling the use of homothetic mapping in real telescope systems for observations on the sky. The...

Experimental performance of homothetic mapping for wide field interferometric imaging

Homothetic mapping is an aperture synthesis technique that allows interferometric imaging over a wide field-of-view. A laboratory experiment was set up to demonstrate the feasibility of this technique. Here, we present the first static experiments on homothetic mapping that have been done on the Delft Testbed for Interferometry (DTI). Before a...

DARWIN nulling interferometer breadboard II: Design and manufacturing

Nulling interferometry is a direct method to detect earth-like planets. To determine whether a planet is earth-like spectrometry can be performed which requires a broadband optical input signal from the planet. Nulling interferometry should decrease the broadband (λ ≈ 6-18μm) star signal by about a factor of 106. For an ESA contract a nulling...

In-process measurements of material removal in fluid jet polishing

A prototype of a system for in-process monitoring of material removal in fluid jet polishing (FJP) is presented. The measurements make use of temporal phase unwrapping (TPU) allowing for a large working range. The measurement system will be discussed, with all problems that had to be overcome like water on the surface and vibrations, as well as...

Delft Testbed Interferometer: layout design and research goals

The Delft Testbed Interferometer (DTI) will be presented. The main purpose for the DTI is to demonstrate the feasibility of homothetic mapping, both fixed and under scanning conditions. The driving design issues behind the DTI will be presented together with a list of experiments to be conducted with the DTI system in the field of wide field...

The PHARUS System: An Overview and Recent Developments

The PHARUS system is a fully polarimetric C-band SAR wíth an active phased array anrenna. PHARUS is an experimental system. It is meant for remote sensing research in many application areas, both civil and military, maritime and on land. The system performed its first test flight in 1995. In the following years a large amount of data was...

Application of fiber optic interferometers for Cook-off measurements

A fiber optic interferometer comprising of a Sagnac interferometer and a Mach-Zehnder interferometer was developed. The interferometer enabled detection of explosive subtonic expansion velocities during the Cook-off test. The system enabled a comparison between the results of the two interferometer systems caused by the application of two...

Development of fiber optic sensors at TNO for explosion and shock wave measurements

Fiber Optic sensors are found to be very suitable for explosion and shock wave measurements because they are immune to Electromagnetic Interference (EMI). In the past few years, TNO has developed a number of sensor systems for explosion and shock wave measurements in which the optical fiber is a vital component. This paper presents a survey of...

Monitoring the urbanisation of Dar es Salaam using ERS SAR data

Airborne Repeat Pass Interferometry for Deformation Measurements

In ground engineering the need for deformation measurements is urgent. SAR interferometry can be used to measure small (sub-wavelength) deformations. An experiment to investigate this for dike deformations was set up, using the C-band SAR system PHARUS (PHased ARray Universal SAR). This paper describes the progress made in the research.

Study of blast wave interactions with structures using a phase-stepped double reference beam holographic interferometer

An optical study of blast wave propagation and interaction with multiple structures is presented, as well as a method for obtaining quantitative information on the pressure distribution from a number of phase-stepped images. The blast load distribution on buildings is studied by scaling down the buildings and exposing to a plane shockwave in a...

Satellite Radar Measurements of Land Subsidence

The potential of satelliteborne interferometric measurements for the mapping of slow land subsidence has been investigated. Two test sites, covered by the E,RS-1 satellite, were selected in the Netherlands: the provinces of Groningen and Zeeland. In situ measurements on the weather and the actual subsidence were gathered. It will be shown that...