Philipp HukeHochschule Emden/Leer · Faculty of Technology
Philipp Huke
Professor
About
60
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416
Citations
Citations since 2017
Introduction
Additional affiliations
September 2020 - present
December 2014 - August 2020
November 2009 - October 2014
Education
April 2005 - February 2009
September 2002 - November 2004
September 1998 - August 2002
Publications
Publications (60)
Direct metal deposition (DMD) can be used for the cladding of surfaces as well as repairing and additive manufacturing of parts and features. Process monitoring and control methods ensure a consistent quality during manufacturing. Monitoring by optical emission spectroscopy of the process radiation can provide information on process conditions and...
Light of a stabilized laser frequency comb is coupled into a multimode fiber and recorded with a Fourier-Transform spectrometer. The interferograms consist of equidistant, burst-like interference signals, which decorrelate due to modal dispersion and distribution.
HIRES will be the high-resolution spectrograph of the European Extremely Large Telescope at optical and near-infrared wavelengths. It consists of three fibre-fed spectrographs providing a wavelength coverage of 0.4-1.8 mic (goal 0.35-1.8 mic) at a spectral resolution of ~100,000. The fibre-feeding allows HIRES to have several, interchangeable obser...
p>Aims. We analyse the Signal-to-Noise Ratio (SNR) requirements of the European Space Agency (ESA)-funded Solar Coronagraph for OPErations (SCOPE) instrument with respect to the manual and automatic detection of Coronal Mass Ejections (CMEs) in its field of view of 2.5 to 30 solar radii.
Methods. For our analysis, SNR values are estimated from obse...
Statistical analyses from exoplanet surveys around low-mass stars indicate that super-Earth and Neptune-mass planets are more frequent than gas giants around such stars, in agreement with core accretion theory of planet formation. Using precise radial velocities derived from visual and near-infrared spectra, we report the discovery of a giant plane...
We have used a laser frequency comb with a repetition frequency of νrep≈1 GHz to measure the drift and dispersion of a Fourier-transform spectrometer (FTS). We used the electronic measurements of νrep and νCEO to create a reference line list. We measured 28 interferograms and computed the phase and power spectra. The analysis of the interferograms...
Context. Teegarden's Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0V), the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys such as CARMENES. Aims. As part of the CARMENES search for exoplanets around M dwarfs, we obtain...
Fourier-transform spectrographs (FTS) are among the most important tools for high-resolution spectroscopy over a broad spectral bandwidth. Usually, the frequency axis of an FTS is calibrated with relatively few atomic lines and an absolute wavelength reference, which is often a stabilized He–Ne laser. Normally, the phase-spectrum is measured using...
At the Institute for Astrophysics G¨ottingen we have a very special combination of instruments: A 50 cm Siderostat with a vacuum vertical telescope, a very high resolution Fourier Transform Spectrograph (R > 900; 000 at 600 nm in double sided mode) and a Laser Frequency Comb for extremely precise and accurate frequency calibration. The spectrograph...
Absorption cells filled with diatomic iodine are frequently employed as wavelength reference for high-precision stellar radial velocity determination due to their long-term stability and low cost. Despite their wide-spread usage in the community, there is little documentation on how to determine the ideal operating temperature of an individual cell...
We present precise broadband measurements of absorption and dispersion spectra of carbon monoxide 0-3 band in argon. They were performed using frequency comb cavity mode width and dispersion spectroscopies with a mechanical FTS setup.
Context . Thorium hollow cathode lamps (HCLs) are used as frequency calibrators for many high resolution astronomical spectrographs, some of which aim for Doppler precision at the 1 m s ⁻¹ level.
Aims . We aim to determine the most suitable combination of elements (Th or U, Ar or Ne) for wavelength calibration of astronomical spectrographs, to char...
Absorption cells filled with diatomic iodine are frequently employed as wavelength reference for high-precision stellar radial velocity determination due their long-term stability and low cost. Despite their wide-spread usage in the community, there is little documentation on how to determine the ideal operating temperature of an individual cell. W...
We report on the first star discovered to host a planet detected by radial velocity (RV) observations obtained within the CARMENES survey for exoplanets around M dwarfs. HD 147379 (V = 8.9 mag, M = 0.58 ± 0.08 M), a bright M0.0 V star at a distance of 10.7 pc, is found to undergo periodic RV variations with a semi-amplitude of K = 5.1±0.4 m s −1 an...
The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520--1710nm at a resolution of at least $R > 80,000$, and we measure its RV, H$\alpha$ emission, and project...
Context. The main goal of the CARMENES survey is to find Earth-mass planets around nearby M-dwarf stars. Seven M-dwarfs included in the CARMENES sample had been observed before with HIRES and HARPS and either were reported to have one short period planetary companion (GJ 15 A, GJ 176, GJ 436, GJ 536 and GJ 1148) or are multiple planetary systems (G...
The first generation of E-ELT instruments will include an optical-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long...
On March 20, 2015, we obtained 159 spectra of the Sun as a star with the solar telescope and the FTS at the Institut f\"ur Astrophysik G\"ottingen, 76 spectra were taken during partial solar eclipse. We obtained RVs using $I_2$ as wavelength reference and determined the RM curve with a peak-to-peak amplitude of almost 1.4 km s$^{-1}$ at typical RV...
The first generation of E-ELT instruments will include an optical-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long...
Hollow cathode discharge lamps (HCLs) have been successfully used in recent years as calibration sources of optical astronomical spectrographs. The numerous narrow metal lines have stable wavelengths, which makes them well suited for m/s calibration accuracy of high-resolution spectrographs, while the buffer-gas lines are less stable and less usefu...
We report on the experimental realization of locking a Fabry-Perot interferometer (FPI) onto a stabilized diode laser for the calibration of astronomical spectrographs. The external cavity diode laser (ECDL) is stabilized to the 85Rb+ F∗ = 2 → F = 3 transition with a pump-probe setup. The stability of the 85Rb+ reached between optical clocks is on...
We report about the efficient generation of Lamb waves for nondestructive testing (NDT) of carbon fiber reinforced plastics (CFRP) with spatially formed laser beams. Therefore we describe the successful introduction of a liquid crystal on silicon (LCoS)-based spatial light modulator (SLM) to create predetermined spatial laser light distributions fo...
Phase-measuring deflectometry is a powerful method to measure reflective surfaces. It is relatively easy to extract slope
and curvature information from the measured phase maps; however, retrieving shape information depends very
sensitively on the calibration of the camera and the geometry of the measurement system. Whereas we have previously
demon...
Nondestructive testing of objects is the basis for quality control in a production line. There exists a wide range of optical
and tactile methods for the detection of surface defects. For hidden defects (below the surface) different methods like Xray
or ultrasound are state of the art; also, optical methods like thermography and interferometry can...
The application of laser ultrasound for nondestructive testing of carbon fiber-reinforced plastics (CFRP) and carbon fiber-reinforced thermoplastics (CFRTP) is shown. Laser-generated excitation creates a three-dimensional, thermoelastic zone which emits ultrasound waves during expansion and contraction. In order not to exceed the damage threshold o...
The verification of kissing bond defects with conventional nondestructive testing techniques is generally unsuccessful because kissing bonds behave very similar to an intact adhesive. Therefore, one has to apply a suitable method such as loading the adhesive joint using laser-generated shock waves in order to make this kind of defect detectable. Th...
We report on a 3.3 μm laser/optical parametric oscillator system with 4.7 mJ pulse energy for laser ultrasound measurements of carbon-fiber-reinforced materials. The OPO was pumped by a compact diode-pumped Nd:YAG master-oscillator power-amplifier system with two amplifier stages. First results of laser ultrasound measurements are presented.
Non-destructive testing (NDT) describes a wide range of methods for measuring and comparing physical quantities against a nominal condition. In this paper we describe and compare different optical NdT (ONDT)-methods with respect to their characteristics and capability for different measurement tasks. ONDT may be specified in two categories, passive...
We present a method to record the wear on samples of micro deep drawing
tools. The method is based on the basic idea of comparative holography
and captures three dimensionally the surface of the tool in the initial
state and compares it with used state after processing several parts.
The comparison reveals scratches and other effects caused by wear...
IntroductionPrinciples of Optical Nondestructive Testing Techniques (ONDTs)Optical Methods for NDTConclusions and PerspectivesAcknowledgmentsReferences
Also available on NDT.net, vol. 17, january 2012
http://www.ndt.net/article/ndtp2011/papers/31_Sfarra_Rev1.pdf
Standard ultrasound methods using a phased-array or a single transducer are commonly used for non-destructive evaluation (NDE) during manufacturing of carbon fiber reinforced plastics (CFRP) parts and certificated testing schemes were developed for individual parts and geometries. However, most testing methods need direct contact, matching gels and...
High precision optical metrology may be viewed from the perspective of the relevant object properties for optical measurement such as microstructure, surface gradient and geometrical complexity. We discuss high precision measurement methods and compare their suitability with respect to these object properties. We emphasize reflectometry and shearog...
We present a novel approach to investigate the shape of a diffusely reflecting technical object. It is based on a combination of a multiple‐illumination contouring procedure and phase retrieval from a set of intensity measurements. Special consideration is given to the design of the experimental configuration for phase retrieval and the iterative a...
Optical methods are extremely useful for Non Destructive Testing (NDT) due to their ability to measure fast and contactless, to test larger areas or tiny spots in a short time, and to measure on complex shaped parts as well as plane surfaces. In this paper we present laboratory setups for NDT available at BIAS and corresponding results. We present...
We present a novel approach to investigate the shape of a diffusely reflecting technical object. It is based on a combination of a multiple-illumination contouring procedure and phase retrieval from a set of intensity measurements. Special consideration is given to the design of the experimental configuration for phase retrieval and the iterative a...
![Fig. 1. Overview on optical measurement methods from [5] extended with...](profile/Philipp-Huke/publication/238024062/figure/fig1/AS:393270598356994@1470774425787/Overview-on-optical-measurement-methods-from-5-extended-with-the_Q320.jpg)
The development of a modified stripe-pattern projection system that uses linescan cameras is presented. The system measures complex-shaped sheet metal parts (>3 m2) and enables the detection of dents (>30 mum) and other defects. Therefore, the measurement system is moved and the parts are scanned line by line. The parallel investigation of a simula...
We present a simple scheme for tuneable relative frequency stabilization of lasers. A highly sensitive and accurate frequency-to-voltage
converter is used to derive an error signal from the beat note between two lasers. We analyze in detail detector noise and
drift, modulation detection bandwidth, and cross-talk from power modulation. The results i...
We present a diode laser concept for precision spectroscopy which is based on a novel optical feedback scheme that combines excellent frequency stability (<35kHz linewidth in 290ms) with good tuneability (45 GHz continuously, 50nm overall).
We present theoretical and experimental investigations on a new optical feedback concept for single mode diode lasers. It is based on the optical feedback from a resonant external cavity coupled to the diode laser through the 1st order diffraction of a grating. With a single mode diode laser operating at 852 nm we demonstrate a short term line widt...
We report on the development of a diode laser system which is optimized for precision spectroscopy. It is based on a combination of diode lasers with optical feedback from a grating and diode lasers with optical feedback from a resonant cavity. So far we have achieved overall tuneabilities on the order of 50 nm, continuous tuneabilities in excess o...
We demonstrate a linewidth of 35 kHz with a single mode diode laser operating at 852 nm phase-locked to another laser system that is frequency locked to a Cs-transition. A large continous tuning range in excess of 45 GHz and single mode operation were shown from 829.2 nm to 874.1 nm at constant diode temperature. The external cavity is stabilized t...
We describe a concept for diode lasers with optical feedback. It is based on the combination of two different diode laser concepts: the diode laser with (i) feedback from a grating and (ii) resonant optical feedback from a separate cavity. The goal of our work is to unite the excellent tunability and well known reliability of grating diode lasers w...
Projects
Projects (2)
The foreseen E-ELT instrumentation plan includes a high -resolution spectrograph (HIRES). One of its aims is to detect and quantify exoplanets atmospheres.
Therefore, the fiber-fed spectrograph aims at very high RV-precision. For one of its since cases it even needs 2 cm/s. In addition a high SNR is needed, which in turn requires a sophisticated calibration strategy.
The Project aims at the realization of a method for an automated quality inspection of cold formed micro parts. The result will be a fast and calibrated 3D-metrology system that can automatically measure deviations of object geometries in a measurement volume of about 1 mm3.
