An overview will be given for a series of compact optical systems for measurement of surface displacement. These systems are particularly well suited for miniaturization due to the limited demand for spatial and temporal coherence of the source. Specifically, systems for linear and angular displacement will be described. The systems have been realized based on the use of holographic optical elements but implementations with various kinds of compact diffractive optical elements will be devised. Common features with most of the proposed systems are the use of common-path interferometry and the simultaneous recording of the transmitter and receiver optics, strongly reducing any demand for alignment after assembly. Further, the use of common path systems will reduce the sensitivity to optical turbulence and may reduce the influence of contamination of the optical window.

Today's semiconductor industry is based on silicon as a semiconductor with excellent mechanical, chemical and electrical properties. Additionally, silicon is very effective in converting photons in the wavelength range of 0.1 - 1150 nm into charge carrier pairs. While this photoconversion process occurs essentially noise-free, the electronic detection of the collected photocharge is effectively responsible for the photodetection noise. The limiting physical effect is Johnson (resistor) noise in the channel of the first detection transistor, which depends on the input capacitance, the temperature and the detection bandwidth. This relationship can be exploited in several ways for the realization of image sensors in CCD and CMOS technology that exhibit sub-electron detection noise, reaching the ultimate physical limit of single-photon detection. Additionally, a physical effect can be employed for the amplification of charge signals before the actual electronic detection process: avalanche multiplication. Many of the described low-noise image sensors can be implemented in standard CCD or CMOS fabrication processes, opening up exciting prospects for affordable optical microsystems performing at the physical photodetection limits.

Holographic lithography's unique capacity for high- resolution and large-area pattern transfer offers significant advantages for fabricating a range of optical microsystems. Two industrialized models of lithographic system have been constructed. The first has an imaging resolution of 0.25 micrometers over an exposure field of 6' X 6' and can print onto a variety of substrate types of dimensions up to 6' X 6'. It includes an alignment system permitting a pattern-to-pattern overlay accuracy of 0.3 micrometers (3(sigma) value). The second model combines an imaging resolution of 0.25 micrometers with an exposure field of 10' X 12' and prints onto substrates up to 470 mm X 370 mm. This system has a substrate stepping capability allowing a pattern to be replicated many times onto the substrate, and an alignment system providing 0.5 micrometers overlay accuracy. Both models operate at an exposure wavelength of 364 nm, making them compatible with standard i-line photoresist processing. The technology has been successfully employed for printing grating structures with periods down to 0.5 micrometers for such applications as high-resolution encoders and optical interconnects.

The disadvantages of traditional methods of edge grinding silicon wafers are discussed. With the industry's move to 300 mm format wafers, comes the pressure of environmental issues to minimize acid etch from the wafer process which is commonly used to improve surface finish and reduce sub surface damage. The recent work of Cranfield Precision in wafer edge processing is described, together with descriptions of a new grinding process and machine to eliminate grinding induced damage and minimize the polishing time.

We will discuss the design of surface structured optical elements (corrugated gratings) in fused quartz for application in the short wavelength range, namely as antireflection surface, as (lambda) /4-phase-plate, as polarization beam splitter and as highly efficient phase mask for writing fiber Bragg gratings in monomode fibers. Experimental results will be presented and are found to be in good agreement with theory.

Materials and techniques for manufacturing replicated micro- optical elements are reviewed. Factors such as choice of material, changes in physical dimensions, feature size and cost are considered. The manufacture of a 1.5 micrometers period radial grating for a rotation encoder is described. Replicas of the grating were made from the same Ni shim by reel-to- reel UV embossing, CD injection molding and flat bed hot embossing. The dimensions of the replica parts were measured and compared. The diffraction efficiency of the UV embossed replicas was found to be only slightly less than the theoretical maximum efficiency.

Silicone rubber may very conveniently be used to cast a mold from a variety of surface-relief optical components and surfaces. From this it is very simple to cast replicas in epoxy resin. The method owes its success in a large part to the flexibility of the rubber mold which eases the process of separation both from the master and from the final replica. However, the flexibility also gives rise to distortions in the final replica. This paper reports preliminary work to quantify these distortions under various casting conditions.

Contactless embossing of microlenses (CEM) is a new fabrication technique for the production of refractive microlens arrays. The basic idea is that the surface of the microlenses has no contact with the compression molding tool during the shaping of the surface relief. A high precision matrix of holes made by LIGA microfabrication is used as a compression molding tool. This tool is pressed onto a thermoplastic sample which is heated close to the material's transformation temperature. The material bulges into the openings of the molding tool due to the applied pressure. It process conditions are properly set, the material forms lens-like spherical structures. Microlenses and arrays of microlenses with lens diameters between 30 micrometers and 500 micrometers have been fabricated in thermoplastic material. Besides highly accurate microlens arrays, CEM also provides the potential of cost-effective production and high precision mounting concepts.

A novel method for fabricating microlens arrays (MLA) with continuous phase-relief has been proposed in this paper. It includes three main parts in details: obtaining continuous exposure on photolithographic materials by using moving mask method; fabricating continuous MLA on gelatin by enzyme treatment; replicating MLA to polymer by prepolymerize monomer injection molding techniques. The microlens has parabolic section profile and no dead area, it has the merits of high integration, high energy usage, and less chromatic aberration, especially is useful for broadband application. This method is fast and more convenient than binary optics method or laser direct writing techniques.

An experiment which a diffractive microlens array on germanium is used for enhancing the fill factor of infrared focal plane array has been described in this paper. In order to achieve higher effective fill factor, the diffractive efficiency of each microlens and the transmissivity of the final element must be emphasized. The fabrication and the anti-reflection film evaporation for the diffractive microlens array have been studied. Based on a precise mechanics we have designed, a coupling experiment has been done and the main performance has been discussed. The fill factor of 80% is expected to be reached for the detector with original fill factor of 25%.

A new method for replicating microoptics elements is presented. The principle and technological process of the method are introduced. For PMMA, deep binary relief gratings on quartz substrate and parabolic lenses array in gelatin on glass substrate are replicated by using this new method. The relief-transfer efficiency and transparency of the replicas are measured. The results show that the replicas are of high fidelity of profile.

Integrated optical wide band sources based on thermal and plasma emitters are expected to find broad applications in optical microsystems, e.g. for medical and experimental analysis. Presently only few designs have been investigated in spite of their promising properties with respect to low power consumption, high modulation frequencies, and self adjusting geometries. This paper presents on presently known designs, their fabrication technologies, and applicability e.g. to micro total analysis systems ((mu) tas). KHz- modulation for tungsten and polysilicon based thermal emitters for the near infrared and visible spectrum at powers in the milliwatt-range are obtained. Plasma emitters driven by DC-, RF- or (mu) W-generators work at powers as low as a few milliwatts and emit in the UV and visible spectrum. They can be used as light sources as well as e.g. directly as specimen specific plasma detectors in micro total analysis systems.

Many industrial applications require high beam quality, compact, reliable and low cost lasers. Microchip lasers combine all these advantages. Indeed, solid state Nd:YAG microchips have the beam quality of solid state lasers. Thanks to a monolithic design avoiding any alignment of the laser cavity elements (saturable absorber and mirrors), microchips are compact, reliable and can be produced in large quantities. They can be integrated into micro-systems to make microchip laser sources.

An efficient method was developed to couple a diode laser to a high contrast waveguides. The laserdiodes were mounted with sub-micron precision using a thermocompression mounting technique. An AlGaAs ((lambda) equals 850 nm) laserdiode was coupled to a SiON based slab waveguide (efficiency (eta) EQ 25 - 30%) and to a Si₂N₄ based ridge waveguide (efficiency (eta) equals 20%) on silicon. A start has been made with the determination of the lifetime of thermocompression mounted laserdiodes. AlGaAs ((lambda) equals 850 nm) lasers as well as AlGaInP ((lambda) equals 675 nm) lasers were tested. The first results indicate that lifetimes in the range 10 - 30 years are possible for CW operation at 30 degree(s)C. The laser- waveguide coupling technique is demonstrated in a sensor platform.

Short amplifying waveguides in which the dopand is confined to the waveguide core were realized by a new glass processing technology with high demands to the optical and thermal properties of the core, cladding and substrate glass. By the improvement of the etching procedures primary structures with a roughness of less than 50 nm were obtained. Simulations, which showed that in a 12 cm waveguide 20 dB gain can be achieved at 1549 nm, were made to evaluate the potential of the amplifier. Gain measurements were performed in waveguides with a dopand concentration of 3 wt.% erbium and an internal gain of more 3.7 dB was achieved in a 1.8 mm glass waveguide at a wavelength of 1549 nm.

The utilization of micro-optical components in systems for optical beam deflection and modulation offers the possibility for realization of miniaturized switches and scanners. As the required displacement of the micro-optical components for efficient beam manipulation is quite small, high speed actuators with small electrical power consumption can be used. We present micro-optical configurations and discuss their potential for the creation of different types of miniaturized switches. The combination of micro-optical components already available and semiclassical piezoelectric actuators leads to new types of switching and modulation systems for a very broad spectrum of applications.

High resolution optical encoders take advantage of diffraction and interference properties of light. In such components, the scale is a phase grating that diffracts light into several orders; an optical reading system makes two of them to interfere. In state of the art systems, the orders interfere after they have been spatially separated from other orders; this leads to cumbersome reading heads. A compact, fully diffractive optical reading system was designed and realized. This reading system was used for the realization of rotation encoders. Using the competences of the Eureka EU 922 FOTA project partners, the encoder phase gratings were successfully realized and the reading system was implemented in standard rotation encoder housings. Without interpolation the encoder gives 480'000 pulses per revolution with a repeatability of 2.5 pulses.

A microoptical receiver module for very high bitrates was designed and realized. We employed well established silicon technologies for integrating the optical components of the microoptical system. For reducing the optical spot size on the photo diode due to the beam divergence of the transmission fiber a monolithically integrated silicon microlens was used. The microlenses were fabricated by melting of photoresist and transferring the preforms into the silicon substrate. We characterized the lenses by lateral shearing interferometry in transmission. The beam diameter on the photodetector (l/e²) could be reduced by about one order of magnitude to less than 10 micrometers . The sensitivity of the modules was about 0.5 A/W at 1310 nm and 0.6 A/W at 1550 nm.

The packaging of a miniaturized NIR-spectrometer is demonstrated. The heart of this NIR-spectrometer is an electrically tunable silicon surface micromachined Fabry- Perot interferometer (FPI). For reliable operation, the FPI device has to be mounted so that thermo-mechanical stresses are not present in its active area. This can be realized basically by mounting FPI on a substrate that has a thermal expansion coefficient close to silicon, using elastic material for mounting or minimizing the joint area between FPI and substrate. The FPI provides the possibility for the manufacturing of a miniaturized single-axis NIR-spectrometer for large-volume applications.

A new conception of adaptive, high resolution, selfdiffractive microsensor for remote displacement measurements is presented. The sensor is sensitive in 3D space and can provide in-plane and out-of-plane displacements simultaneously and separately.

We report on our activities in the design, fabrication, characterization and system integration of planar micro- optical elements. Microlens arrays, gratings, diffusers, beam shapers and beam splitters have been fabricated, tested and integrated in chemical analysis systems ((mu) TAS, fluorescence detection), tracking sensors for satellites, displacement sensors, optical lightpipes, LCD projector illumination photospectrometers, neural networks and multiple channel imaging systems for photolithography. Packaging and alignment strategies for sensors and optical microsystems were investigated.

Fine gratings with spatial periods below one micron, either ruled mechanically or patterned holographically, play a key role as encoders in high precision translational or rotational coordinate or measuring machines. Besides, the fast in-line characterization of submicron patterns is a stringent demand in recent microelectronic technology. Thus, a rapid, destruction free and highly accurate measuring technique is required to ensure the quality during manufacturing and for final testing. We propose an optical method which was already successfully introduced in semiconductor industry. Here, the inverse scatter problem inherent in this diffraction based approach is overcome by sophisticated data analysis such as multivariate regression or neural networks. Shortly sketched, the procedure is as follows: certain diffraction efficiencies are measured with an optical angle resolved scatterometer and assigned to a number of profile parameters via data analysis (prediction). Before, the specific measuring model has to be calibrated. If the wavelength-to-period rate is well below unity, it is quite easy to gather enough diffraction orders. However, for gratings with spatial periods being smaller than the probing wavelength, merely the specular reflex will propagate for perpendicular incidence (zero order grating). Consequently, it is virtually impossible to perform a regression analysis. A proper mean to tackle this bottleneck is to record the zero-order reflex as a function of the incident angle. In this paper, the measurement of submicron gratings is discussed with the examples of 0.8, 1.0 and 1.4 micron period resist gratings on silicon, etched silicon oxide on silicon (same periods) and a 512 nm pitch chromium grating on quartz. Using a He-Ne laser with 633 nm wavelength and measuring the direct reflex in both linear polarizations, it is shown that even submicron patterning processes can be monitored and the resulting profiles with linewidths below a half micron can be characterized reliably with 2(theta) - scatterometry.

We develop a novel and efficient method to simulate diffraction patterns in the far field and in the Fresnel region when the phase counters of a quantized diffractive optical element are approximated by arbitrary polygons. Approximation causes signal errors whose effects have not been extensively studied so far. We take the polygonal shapes into account without any further approximations in the simulation, in contrast to calculations based on direct application of the Fast Fourier Transform. The method is applied to diffractive Fresnel lenses, axicons and gratings with finite size.

We describe the characterization of chirped phase masks made by electron beam writing and reactive ion etching in pure silica. The phase masks are designed to be used as diffractive optical elements in the process of manufacturing of fiber Bragg gratings (FBG). With the technologies available at our institutes grating structures with periods less than 200 nm can be realized in fused silica. Phase masks for writing ideally chirped FBG would require grating structures with continuously changing period. However because of the limited position accuracy of any e-beam writer, it is not possible to generate the desired continuous variation of the grating period. There appear discrete displacement steps with deviations of some nanometers. We obtain some information about the parameters of the phase mask from the properties of written fiber gratings. A sequence of short fiber gratings is written in order to characterize the phase mask. We use a slit to expose a definite small part of the phase mask pattern during the writing process of each short fiber grating. The center wavelength of each fiber grating is analyzed.

A simple, efficient and reusable fiber-to-chip interconnect is presented. The interconnect is based on a V-groove (wet- chemically etched) in silicon, combined with a loose-mode Si₃N₄-channel waveguide. The loose-mode waveguide is adiabatically tapered to the integrated optical (sensor) circuitry. This adiabatic taper enables the dimensions of both the integrated optical sensor circuitry and the loose- mode waveguide section to be designed independently. The coupling efficiency of the `plug-it-in' interconnect is tunable between zero and the maximum obtainable value by tightening two adjustment screws. Coupling efficiencies up to 60% using TE-polarized light at wavelength of 632.8 nm have been reproducibly measured.

The paper presents a new concept of a micromachined integrated sensor for combined atomic force/near field optical microscopy. The sensor consists of a microfabricated cantilever with an integrated waveguide and a transparent near field aperture tip. The advantage compared to the fiber based near field tips is the high reproducibility of the aperture and the control of the tip-sample distance by the AFM-channel. The aperture tip is fabricated in a reliable batch process which has the potential for implementation in micromachining processes of scanning probe microscopy sensors and therefore leads to new types of multifunctional probes. For evaluation purposes, the tip was attached to an optical fiber by a microassembly setup and subsequently installed in a near-field scanning optical microscope. First measurements of topographical and optical near-field patterns demonstrate the proper performance of the hybrid probe.

The thickness non-uniformity and refractive index in- homogeneity of silicon oxynitride thin films, grown by low pressure chemical vapor deposition, have been optimized. The present work was especially motivated by the application of these thin films as well defined waveguides in phase-matched second harmonic generating devices, which are well known for their extremely high requirements to uniformity and homogeneity. However, other demanding integrated optical components like gratings, sensor systems, telecommunication devices, etc., also strongly benefit from highly uniform waveguides.

The blazing effect of parallelogramic grooves is analyzed theoretically and demonstrated experimentally in the case of TE and TM modes in large guidance waveguides. A novel fabrication method is proposed, modellized and demonstrated.

In this paper a method is introduced which makes it possible to choose the paraxial field distribution generated by a diffractive element independently for two perpendicular polarization directions. For that the local transmission of a binary element is controlled by metal-stripe subwavelength gratings of different grating directions fabricated by electron beam lithography. The method based upon the property of these gratings to influence the intensity of an incident wave dependent on their polarization direction. In first experiments such diffractive amplitude elements have been fabricated successfully with the electron beam lithography system LION LV1.

Diffracting optical components possess certain features that differ from reflecting or refracting optics. We discuss how these properties arise and illustrate how they may be used to advantage in metrology and sensing.

In security monitoring, fiber-optic sensors are advantageous because strong and rugged optical fibers are thin, light, flexible and immune to electromagnetic interference. Optical fibers packaged into cables, such as, building and underground cables, can be used to detect even slightest disturbances, movements, vibrations, pressure changes and impacts along their entire length. When running an optical cable around a structure, and when using speckle pattern recognition technique for alarm monitoring, the distributed monitoring of the structure is possible. The sensing cable can be strung along fences, buried underground, embedded into concrete, mounted on walls, floors and ceilings, or wrapped around the specific components. In this paper, a fiber-optic security monitoring sensor based on speckle pattern monitoring is described. The description of the measuring method and the results of the experimental fiber installations are given. The applicability of embedded and surface mounted fibers to monitor the pressure and impact induced vibrations of fences and concrete structures as well as the loosening of critical parts in a power plant machinery were demonstrated in field and laboratory conditions. The experiences related to the applications and optical cable types are also discussed.

The term smart structure has traditionally been used for structures with sensing capabilities, and preferably also actuators and local processing capability of sensor signal to close the feed back loop. To a large extent the terminology has been extended to cover structures with more limited capabilities, but where at least a sensor is closely integrated in the structure. This presentation will give examples from areas where SINTEF have investigated fiber optic sensors and discuss smart structures on this basis.

Electric and magnetic fields can be measured optically, either directly via Pockels and Faraday effect or indirectly via Piezo effect. In high voltage applications fiber optic sensors are especially attractive for their ability of easy potential separation. For electric fields the Pockels effect in BSO, BGO crystals is mostly read out polarimetrically. The current is mostly measured via the Faraday effect in fibers or bulk optics polarimetrically, but also by means of a Sagnac interferometer. Electrooptic voltage and magnetooptic current sensors have quite a matured state of development and shown their benefits in a lot of field tests and installation in high voltage switch gears.

There is strong interest to develop fiber-optical sensing systems for long term surveillance and structural monitoring. Although many detection schemes have been proposed, industrial acceptance of optical fibers as validated replacement of other sensors is limited. Low cost manufacturability, reliability, and long term stability are very important for usability in concrete and composite material structures. Lifetime for major structures in civil engineering of 50 - 100 years are very demanding on the sensors and require accurate aging models and test data to demonstrate their reliability and durability. Acceleration factors of several orders of magnitude can be achieved under reasonable testing conditions depending on temperature, mechanical stress, humidity, chemical environment and activation energy of the damaging process. We report on accelerated aging tests and failure mechanisms of optical fibers and Bragg gratings at elevated temperature, humidity and mechanical stress. Aging behavior is discussed and results from field measurements of large civil structures are presented.

A fiber optic pore water pressure sensing system for structural monitoring of a large dam at L'eau d'heure in Belgium by M.R.H. Voet, B. Verwilghen. The concept and performances of a fiber-optic pore water pressure sensor is discussed for a specific geotechnical application. Monitoring of experimental conditions in the underground inspection galleries and drainage holes underneath the dam is a first aspect and construction and operation of the artificial water dam is the second aspect of structural monitoring. The monitoring of engineering, geotechnical, and operational parameters (total pressure, pore water pressures, waterflow rates, etc.) are essential in these test and site survey programs. Comparison with parallel hydraulic and pneumatic measuring systems has been conducted. Performance of a distributed fiber optic network survey system, including eight sensors interconnected in a ring structure up to 64 sensors, is discussed. The fiber optic interrogating method (time domain multiplexing/frequency domain multiplexing) is described and typical results are presented.

Three different fiber sensor systems using gratings are presented. Firstly, using an acousto-optic tunable filter and closed loop feedback, arrays of fiber Bragg gratings are being used to monitor small-scale perturbations in composite materials by mapping the strain field around a defect. Gratings are also used as distributed sensors by measuring the wavelength as a function of distance. Low-coherence interferometry selects the location under interrogation and a tunable filter measures the local wavelength. An open loop interrogation technique using a commercially available optical coherence domain reflectometer is demonstrated. The reflectivity of the sensor grating is measured as a function of both distance and wavelength. Gratings 40 cm long are interrogated and several distributed grating sensors are multiplexed in an array. Thirdly, a new sensing concept using subcarrier fiber gratings (SFGs) has been proposed and modelled. The SFG is a periodic reflective array resonant at RF frequencies. The resonance may be measured using subcarrier interferometry. Modelling has demonstrated the SFG to have superior performance over other subcarrier sensors.

A method of interrogation of a quasi-distributed sensor in the frequency domain is discussed. The sensor consists of a series of pairs of the identical Bragg gratings imprinted in the fiber core along its length. Each pair of the Bragg gratings performs as a low reflective Fabry-Perot interferometer producing a cosine modulated reflection spectrum within a grating's main lobe. The detector signal represents the superposition of the modulated reflection spectra which can be decomposed using the fast Fourier transform.

In this paper we present results of our stabilization scheme for an optical fiber Mach-Zehnder interferometer with a diode laser as light source. It is developed for compensating the drift path difference produced by external parameters as the environmental temperature. The optoelectronic setup in which the interference signal is fed back to the injection current of the laser diode is investigated in order to obtain a stabilized system. Details on parameter characterization, system design and the results observed are given.

In this paper, we report an Artificial Neural Network approach for simultaneous recovery of strain and temperature from the outputs of fiber optic sensors. Simulation results for both linear and non-linear sensing schemes are presented.

Intrinsic advantages of fluorescence lifetime based optical sensors, as referred in the literature, are their stability towards source fluctuations and self-reference. The latter can be interpreted also as non-dependence on geometrical design and other properties of the constructed sensor. In the article presented it is shown this is not the case. The measured fluorescence decay time, which should be unambiguously connected to the measured quantity (temperature, for example), shows an intricate dependence on source, geometrical properties and signal processing technique. Numerical calculations together with theoretical discussion are employed to quantize and interpret this effects, mainly caused by reabsorption. Different sensor designs are compared, an optimal sensor construction suggested and alternative digital signal processing technique introduced.

Amongst the various sensing principles studied for use in optical fiber sensors, color coding has proven to be successful in commercial applications. Color coded sensors are based on commercially available and easy to handle components (i.e. LED's, lasers, multimode fibers) and the same basic optoelectronics can be used for a wide variety of applications. Such applications are: the remote measurement of chemical composition (pH, hydrogen, oxygen, aromatic hydrocarbons, humidity etc.), biochemical reactions and physical parameters (e.g. temperature, pressure, etc.) in medical applications (e.g. blood gas analysis, immunosensors, etc.), environmental monitoring, process control and on the factory floor. A versatile transmitter/receiver-module, which can be easily customized, has been developed as a multi chip module (MCM). This MCM can be directly mounted onto the printed circuit board, is small in size (50 X 50 X 12 mm³) and contains all optical, optoelectronic and electronic components and circuits to interface optically with the sensors and electrically with the microprocessor and its associated circuitry used for data analysis. Up to four sensors can be connected to one module and individually interrogated under software control. The design and the characteristics of the MCM as well as its application in possible sensor arrangements will be discussed with special emphasis on its use in a four channel fiber optic temperature sensor.

The principle of an interferometric single-mode fiber optic sensor using birefringent components and a broadband source is described. This device is sensitive to the magnetic field variation or to the mechanical rotations of its components. In this paper, we show that only one additional birefringent element is needed to make this fiber optic sensor. Besides, this device can be used for characterizing optical fibers or any birefringent element inside the Sagnac.

A cost-effectively designed polychromator using holographic grating as spectral dispersive element and CCD line array as detector is applied to the multiplexing of a many-element fiber grating sensor network for measuring temperature and stationary strain. The influence of intensity and polarization fluctuations in the superluminescent diode as a broadband light source, and in the fiber transmission lines as well have been minimized by reducing parasitic reflections and introducing depolarizing elements. Other error sources of the sensor read-out stability have been reduced by appropriate peak fitting procedures of the CCD pixel intensity distribution and by the consumption of mechanically stable sensor heads for temperature and strain sensing with low cross sensitivity. A special mounting technique allowing compensation of thermally induced Bragg wavelength shifts is used for obtaining a wavelength reference in the polychromator. Thus, stability of wavelength readout is only noise-limited with a rms value of about 0.2 pm and yields a resolution and stability for measurement of temperature <EQ 0.1 K and for stationary strain <EQ 0.l5 (mu) (epsilon) .

A novel method for the directional multicomponent laser Doppler velocimetry, LDV, based on the generation of different carrier frequencies, one for each velocity component, is presented. The carrier frequencies are generated by a chirp laser frequency modulation in conjunction with fiber delay lines of different lengths. Since the carrier frequency generation is realized without involving additional frequency shift elements like Bragg cells the LDV arrangement can be significantly simplified. Accurate velocity measurements without influence of carrier frequency fluctuations are accomplished by correlating the generated measuring Doppler signal with reference signals, given by the same carrier frequencies. The employed quadrature demodulation signal processing technique enables the measurement of the momentary Doppler frequency in the baseband. This novel LDV system is demonstrated by a directional measurement of two orthogonal velocity components of fluid flows.

The increasing demand of complex micro-optical products such as Diffractive Optical Elements (DOE) requires the development of new optical material processing micro- techniques especially for small-series production. Diamond turning machining is considered an ideal, mature production tool of DOE in ductile materials but not brittle ones. However, the progress in optical material UV-laser machining is proving to be a good candidate for the micro-structuring of glasses. Thus, by using this emergent UV-laser machining technique, DOE prototypes in C2036 have been made and show promising results.