Publications

Journal Papers / Proceedings Papers / Patents – dealing with the following areas:
 
Technologies & Materials

Influence of substrate cleaning on LIDT of 355 nm HR coatings (1997)

Jean DiJon, Pierre Garrec, Norbert Kaiser, Uwe B. Schallenberg
SPIE Proceedings Volume 2966: Laser-Induced Damage in Optical Materials: 1996, , Harold E. Bennett; Arthur H. Guenther; Mark R. Kozlowski; Brian E. Newnam; M. J. Soileau, Editors, pp.178-186

An advanced high-purity reactive e-beam evaporation process was used to deposit Al2O3/SiO2 HR coatings for 355 nm high-power laser applications. Both 1:1 and R:1, 6 ns pulse width, laser-induced damage threshold (LIDT) tests for normal and non-normal incident design were performed to study the influence of quartz substrate cleaning. Damage test results indicate very high LIDT values on clean substrates. Some tested points have R:1 LIDT above 20 J/cm2. Post-cleaning of coated substrates degrades LIDT.

IAD of oxide coatings at low temperature: a comparison of processes based on different ion sources (1997)

Hansjoerg S. Niederwald, Norbert Kaiser, Uwe B. Schallenberg, Angela Duparre, Detlev Ristau, Michael Kennedy
SPIE Proceedings Volume 3133: Optical Thin Films V: New Developments, Randolph L. Hall, Editors, pp.205-213

A comparative study of different ion and plasma assisted physical vapor deposition processes at low temperature is reported. To work out a clear comparison of the different processes, the object of the study are single layers of different metal oxides like Ta2O5, TiO2, SiO2 and mixed oxides like H4 (Merck) deposited on glass and silicon substrates. Three different types of ion- (or plasma-respectively) sources are used: the cold cathode ion source from Denton (CC 104), the end hall ion source Mark II from CSC and the advanced plasma source from Leybold. Each of these processes is run under conditions concerning process parameters like bias, ion current, ion energy, beam characteristics and gas flow, which were understood to be optimized also to maintain long-term stability as realistic production conditions. The resulting metal oxide single layers are characterized by their optical properties, dispersion curves for NUV and VIS as well as absorption and scatter at discrete wavelengths. Also discussed are mechanical properties like hardness and adherence. A test method is presented which clearly shows the superior behavior of the IAD coatings.

Plasma ion assisted deposition of medium and high refractive index thin films (1997)

M. Friz, U. B. Schallenberg, S. Laux
Proc. SVC 40th Ann. Techn. Conf. 1997

Ion-Assisted Deposition of Oxide Materials at Room Temperature by use of Different Ion Sources (1999)

H. Niederwald, S. Laux, M. Kennedy, U. Schallenberg, A. Duparré, M. Mertin, N. Kaiser, and D. Ristau
Applied Optics 38, 3610-3613

Thin films of SiO2, TiO2, Ta2O5, ZrO2, and the mixed oxide H4 (Merck) have been deposited onto nonheated glass substrates by electron-beam evaporation in commercial coating plants. All depositions have been carried out with ion assistance provided by three different ion or plasma sources (end-hall, plasma, and cold-cathode sources). The optical film properties such as index of refraction, extinction coefficient, light scattering, and absorption have been examined by spectrophotometry, laser calorimetry, and total integrated light-scatter measurements. Surface morphology has been investigated by atomic force microscopy studies. Furthermore, films have undergone sand erosion tests for the determination of relative wear resistance. The film properties are compared for the three different ion sources.

Plasma-induced deposition for optical interference filters (2004)

U. Schallenberg, S. Jakobs
Proceedings of the Ninth International Conference on Plasma Surface Engineering

Reliable production of steep edge interference filters (2008)

Marc Lappschies, Peter Pfeifer, Uwe Schallenberg, Henrik Ehlers, Detlev Ristau
SPIE Proceedings Volume 7101: Advances in Optical Thin Films III, Norbert Kaiser; Michel Lequime; H. Angus Macleod, Editors, 71010P

Interference filters for spectroscopic purposes or sensor applications are characterized by strictly specified spectral blocking and transmitting regions with intermediate steep edges. These steep edges must be positioned within nanometer accuracy while the coating may consist of more than one hundred non-quarterwave layers. Though modern ion assisted deposition processes in conjunction with quartz crystal control are well suited for the production of complex filters, an optical monitoring device seems to be necessary to fulfill the demanding spectral requirements. Broad band optical monitoring (BBM) directly on the calotte has been employed to control the production of this type of band stop filters. For a large number of also different types of these coatings the BBM-technique demonstrated its capability to improve the reliability and flexibility in industrial production. Within a stable well-characterized deposition process error self-compensation effects allow for a fast realization of various designs within specified tolerances. Nevertheless, optical broad band monitoring could not be applied to all types of these steep edge filters because error propagation leads to unreachable solutions of the thickness tracing algorithm for specific cases. The given examples of complex steep filters and the corresponding post analysis of stored online spectra as well as the simulation of the monitoring process reveal the influence of the design itself to this occurrence. A suggestion for an identification of critical thickness values within the layer sequence is discussed and solutions to the problems are presented.
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Using Different Thin-Film Design Software for Different Requirements (2009)

Uwe Schallenberg
Proc. SVC 52th Ann. Techn. Conf. 2009
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Characterization of metal-oxide thin films deposited by plasma-assisted reactive magnetron sputtering (2010)

Stefan Jakobs, Marc Lappschies, Uwe Schallenberg, Olaf Stenzel, and Steffen Wilbrandt
COL Vol 8, Suppl. page 1-5
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Identifying Consistent Film Dispersion Data by Online-Spectra and Cross-Check Analysis (2010)

M. Lappschies, S. Jakobs, and U. Schallenberg
Optical Interference Coatings, OSA Technical Digest (Optical Society of America, 2010), paper TuB4.

A precise identification of the dielectric materials dispersion data involved forming the layer stack is crucial for obtaining satisfactory results utilizing optical broadband monitoring for high precision control of optical thin film filters.

 


AR Coatings

Analytical design of multicycle broadband AR coatings (1999)

Uwe B. Schallenberg, Stefan Jakobs, Norbert Kaiser
SPIE Proceedings Volume 3738: Advances in Optical Interference Coatings, Claude Amra; H. Angus Macleod, Editors, pp.230-238

Normal-incidence multicycle broadband AR coatings on glass with low residual over the wavelength region 400 nm to 800 nm are theoretically discussed. Using the method of effective interfaces and the concept of equivalent index layers a 4-layer design sub(AHBL)air is expanded into the designs sub[AH(C2LC)2BL]air where A, B, C, H, and L are quarter-wave layers with refractive indices nH equals 1.38, nL equals 2.35, and nL < n(Lambda ), bB, nC, < nH. These designs represent 1-cycle, 2- cycle, and 3-cycle broadband AR coatings and perform a residual reflectance of 0.20 percent, 0.14 percent, and 0.10 percent, respectively. Four other designs demonstrate the approach at other wavelength regions. In one example, all quarter-wave layers with refractive indices in-between nL and nH are analytically substituted using equivalent index layers to get two-material multilayers suitable for practical applications. After this, the design is refined with respect to the optical thickness whereby the layer number is fixed. The resulting design consists of 18 layers and performs an average residual reflectance 0.085 percent over the region 400 nm to 800 nm.

Reflexionsmindernde Beschichtung aus einem Wechselschichtsystem unterschiedlicher Schichtmaterialien mit jeweils niedrigerem und höherem Brechungsindex (Patent 2000)

DE 000010034158 C2
Anmeldedatum: 10.07.2000
Hauptklasse: C08J 7/06
Erfinder: Kaiser, Norbert; Schallenberg, Uwe; Schulz, Ulrike
Anmelder: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.

Zusammenfassung:
Die Erfindung betrifft eine reflexionsmindernde Beschichtung aus einem Wechselschichtsystem unterschiedlicher Schichtmaterialien mit jeweils niedrigerem und höherem Brechungsindex gemäß den Patentansprüchen. Mit der erfindungsgemäßen Lösung kann die Reflexion von auf die Oberfläche von Substraten auftreffendem Licht effektiv und in hohem Maße verringert werden, was für viele Anwendungsfälle, insbesondere für viele optische Elemente (Linsen, Fenster, Prismen u. a.) oder optoelektronische Elemente und auch für Brillengläser wünschenswert ist. Die Beschichtung kann besonders vorteilhaft zur Reflexionsminderung im sichtbaren Spektralbereich eingesetzt werden.
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Abrasion-resistant antireflection coating for plastics (2000)

Ulrike Schulz, Uwe B. Schallenberg, Norbert Kaiser
SPIE Proceedings Volume 4094: Optical and Infrared Thin Films, Michael L. Fulton, Editors, pp.100-106

Coating of plastics for optical applications is mostly intended to improve their mechanically durability and to provide a desired optical function. A potential layer system to realize an antireflection function and to improve the mechanical properties simultaneously in a combination of hard coating SiO2 with classical 4-layer antireflection system consisting of SiO2 and Ta2O5. Plasma-Ion Assisted Deposition (Plasma-IAD) at room temperature has been applied for coating experiments on PMMA and Polycarbonate. The temperature on a polymer substrate can reach a critical value in respect to its low thermal stability, if thick layers Ta2O5 have to be deposited. The increase of temperature is mainly determined by the radiation heat of electron beam evaporator. With needle optimization, an alternative coating design has been developed. The design is characterized by low thickness of high refractive index layers, which add up to less than about 5% of the total multilayer thickness. The high refractive index layers are almost evenly distributed over the whole stack. The total thickness of this kind of coating is adjustable between 800 nm and about 2600 nm. The mechanical properties of the coating deposited on plastics corresponds to that of a single SiO2 laser of the same thickness.

Reflection Reducing Coating (US Patent 2002)

US Patent 6,645,608 B2
Anmeldedatum: 28.07.2001
Hauptklasse: B32B 7/02
Erfinder: Kaiser, Norbert; Schallenberg, Uwe B.; Schulz, Ulrike
Anmelder: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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Antireflection Coating Design for Plastic Optics (2002)

U. Schulz, U. Schallenberg, and N. Kaiser
Applied Optics 41, 3107-3110

The coating of plastics for optical applications is intended to improve the mechanical durability of soft polymers and to serve an antireflection function. Usually a classic four-layer antireflection system is added on top of a single-layer hard coating. With needle optimization, an alternative coating design has been developed. The design is characterized by thin high-refractive-index layers that are almost evenly distributed over the whole stack. Plasma ion-assisted deposition was used to deposit coatings upon poly(methyl methacrylate), polycarbonate, and cyclo-olefin copolymer. Uniform antireflection and high scratch resistance have been achieved.

Symmetrical Periods in Antireflective Coatings for Plastic Optics (2003)

U. Schulz, U. Schallenberg, and N. Kaiser
Applied Optics 42, 1346-1351

Plastic optical parts require antireflective as well as hard coatings. A novel design concept for coating plastics combines both functions. Symmetrical three-layer periods with a phase thickness of 3/2π are arranged in a multilayer to achieve a step-down refractive-index profile. It is shown mathematically that the equivalent index of symmetrical periods can be lower than the lowest refractive index of a material used in the design, if the phase thickness of the symmetrical period is set equal to 3/2π instead of the usual π/2. The straightforward application of the concept to the design of antireflection coatings in general is demonstrated by example.
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Optisches System zur Verringerung der Reflexion optischer transparenter Substrate (Patent 2003)

DE 000010354091 B4
Anmeldedatum: 11.11.2003
Hauptklasse: G02B 1/11(2006.01,A)
Erfinder: Kaiser, Norbert; Schallenberg, Uwe B.; Schulz, Ulrike
Anmelder: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., mso jena Mikroschichtoptik GmbH

Zusammenfassung:
Die Erfindung betrifft ein optisches System zur Verringerung der Reflexion optisch transparenter Substrate. Dabei ist das Schichtsystem mittels auf der Oberfläche eines jeweiligen Substrates alternierend angeordneten Schichten ausgebildet, die jeweils aus einem Stoff mit kleinerer optischer Brechzahl und einem zweiten Stoff mit höherer optischer Brechzahl gebildet sind, ausgebildet. Sie kann bevorzugt im Wellenlängenbereich des sichtbaren Lichtes eingesetzt werden.
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New AR design concepts with equivalent layers (2004)

U. Schallenberg
Optical Interference Coatings, OSA Technical Digest Series (Optical Society of America, 2004), paper TuB1.

Some new concepts to design AR coatings with equivalent layers are discussed including an approach to use the theory of stopband suppression as one of the basics of broadband AR coatings.

Optical system for reducing the reflection of optically transparent substrates (US Patent 2004)

Patent Application Publication US 2002/0136877 A1
Veröffentlichungsdatum: 26.07.2002
Hauptklasse: B32B 7/02
Erfinder: Schulz, Ulrike; Kaiser, Norbert; Schallenberg, Uwe B.
Anmelder: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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Multicycle AR coatings: a theoretical approach (2004)

Uwe B. Schallenberg, Ulrike Schulz, Norbert Kaiser
SPIE Proceedings Volume 5250: Advances in Optical Thin Films, Claude Amra; Norbert Kaiser; H. Angus Macleod, Editors, pp.357-366

A theoretical approach to design multicycle AR coatings with predetermined residual reflectance, bandwidth, and cycle number is presented. The approach uses a novel step-index concept involving symmetric or asymmetric quarter-wave layer sequences to substitute refractive indices which are less than a given low refractive index. These substitutions result in a chosen step-down index profile matching the refractive index of the substrate to air. Each step of the index profile is the origin of a cycle of the synthesized AR design. Multicycle AR designs for the visible region with bandwidths of 1.6, 2.0, and 3.0 are presented as examples.

AR-hard broadband antireflective coatings generated by a controlled needle-optimization technique (2004)

U. Schulz, N. Kaiser, and U. Schallenberg
Optical Interference Coatings, OSA Technical Digest Series (Optical Society of America, 2004), paper TuB2.

AR-hard designs can be understood as step-down designs composed of layer stacks with low equivalent index. The AR bandwidth can be adjusted in accordance with the optical thickness used for each step.

Antireflection design concepts with equivalent layers (2006)

U. Schallenberg
Applied Optics 45, 1507-1514

Some novel concepts of designing antireflection (AR) coatings with equivalent layers are presented. As an introduction, essential papers concerning thin-film optics and AR designs are cited, and the AR problem and a previously introduced AR-hard design type are discussed. Based on the known matrix formalism, a potential AR region, an equivalent stack index, and an equivalent substrate index are defined to use the theory of stop-band suppression as a starting point for the design of broadband AR coatings. The known multicycle AR design type is identified as a typical solution to the AR problem if the presented approach is used.
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Design principles for broadband AR coatings (2008)

Uwe Schallenberg
SPIE Proceedings Volume 7101: Advances in Optical Thin Films III, Norbert Kaiser; Michel Lequime; H. Angus Macleod, Editors, 710103

It is shown that most of the known AR coatings that start with the famous quarter-half-quarter coating including the multi-cycle designs display simply alternative solutions to replace unavailable refractive indices of a standard solution. On the basis of this viewpoint some design principles are presented that help to derive an approach to solve a given AR problem. Principal objective of the presented approach is the application of previously defined terms 'equivalent substrate index' and 'equivalent stack index' that characterise a quarter-wave optical thickness multilayer system. It is shown that the presented design principles are also suitable if, instead of a thin-film system, a modification of the interface is used to reduce the surface reflection.
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Nanostructures versus thin films in the design of antireflection coatings (2011)

Uwe B. Schallenberg
SPIE Proceedings Volume 8168: Advances in Optical Thin Films IV, Michel Lequime; H. Angus Macleod; Detlev Ristau, Editors, 81681N

It is shown how the discussion about antireflection coatings for the visible and near infrared region has been changed dramatically with recent experimental applications of nanostructures that realize media with effective refractive indices less than the 'magic border' of 1.34. Using the so-called binary optics as an example, a glass-like nanostructure similar to the moth-eye structure is theoretically designed as antireflection coating for the visible and near infrared region. With the aim of this example and considering only known design principles of thin-film optics, a connection between nanostructures and thin films regarding their alternative or combined application as antireflection coatings is presented. As summary regarding the nanostructures vs. thin film discussion, a reference list is presented that cited different types of antireflection coatings presented in the past 70 years with respect to their applications, designs, and deposition technologies.
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Micro Patterning

Verfahren zur Herstellung eines optischen Elementes (Patent 1996)

DE 000019641303 B4
Anmeldedatum: 07.10.1996
Hauptklasse: G02B 5/28(2006.01,A)
Erfinder: Frank, Markus; Schallenberg, Uwe
Anmelder: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.

Hauptanspruch:
Verfahren zur Herstellung eines optischen mikrostrukturierten Elements aus dielektrischen Interferenzschichten, bei dem a) mindestens eine gegenüber dem Trockenätzverfahren resistente und damit als Ätzstoppschicht (2 ) wirkende optische Interferenzschicht aus MgF2 auf der gesamten Fläche des optischen Elements ausgebildet wird, b) auf der MgF2-Schicht ganzflächig ein Schichtaufbau aus einer oder mehreren gegenüber dem Trockenätzverfahren nicht resistenten optischen Interferenzschicht bzw. -schichten aufgebracht wird, wobei bei der Auslegung dieses Schichtaufbaus die optischen Parameter der MgF2-Schicht berücksichtigt werden, so dass die MgF2-Interferenz- und Ätzstoppschicht und der auf diese aufgebrachte Schichtaufbau ein Interferenzschicht-System bilden, c) der Schichtaufbau unter Einsatz eines photolithographischen Maskierungsprozesses mit dem Trockenätzverfahren unter Verwendung fluoridischer Ätzgase in den nicht maskierten Teilbereichen bis zur MgF2-Ätzstoppschicht entfernt wird.
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Microstructured multilayer dielectric coatings with binary optical functions (1996)

Marcus Frank, Uwe B. Schallenberg, Norbert Kaiser
SPIE Proceedings Volume 2776: Developments in Optical Component Coatings, Ian Reid, Editors, pp.330-335

Micropatterned interference filters have been developed by dry etching of dielectric multilayer stacks. Apart from the optical demands on the conventional filter design there are new requirements originating from the patterning process, which has to be stopped at the interface between two layers. In this paper the fundamental problems associated with the design and the development of micropatterned multilayer dielectric stacks are discussed. Details of the production of a two-stage filter array are described and experimental results are presented.

Micropatterned multilayer dielectric filters with two spectral characteristics (1997)

Marcus Frank; Uwe B. Schallenberg; Norbert Kaiser
OE 36, 1220-1224

Dielectric microfilter arrays for multispectral measuring devices (1997)

Marcus Frank, Uwe B. Schallenberg, Norbert Kaiser, Wolfgang Buss
SPIE Proceedings Volume 3008: Miniaturized Systems with Micro-Optics and Micromechanics II, M. Edward Motamedi; Larry J. Hornbeck; Kristofer S. J. Pister, Editors, pp.265-272

For specified color measuring devices miniaturized dielectric filter arrays have been designed and developed. The manufacturing procedure is based on the combination of coating- and micropatterning processes including the employment of etchstop layers. The spectral properties of a basic filter, fabricated as an unpatterned filter blank, have been modified within small areas by reactive ion etching a defined number edge by edge within a period of 25 micrometers . In this paper design and development of two-color microfilter arrays are described and problems are depicted, arising with the production of multicolor dielectric microfilters. An alternative manufacturing procedure is discussed, making it possible to arrange more than two different interference filters edge by edge.

Multispectral dielectric micro-filter arrays for local resolving color sensors (1998)

Marcus Frank, Uwe B. Schallenberg, Norbert Kaiser
OE Volume 37, 2647-2654

Dielectric microfilter arrays for local resolving color sensors (1998)

Marcus Frank, Uwe B. Schallenberg, Norbert Kaiser, Wolfgang Buss
SPIE Proceedings Volume 3289: Micro-Optics Integration and Assemblies, Michael R. Feldman; Yung-Cheng Lee, Editors, pp.193-200

Two different types of color sensor have been developed, which are adaptable to a wide variety of industrial applications. One kind of sensor was developed by depositing dielectric interference filters directly on photoelectric cells, applying a low temperature coating procedure. This way it was possible to accommodate spectral characteristics to the specific spectral sensitivity of the photoelectric cells, minimizing losses by absorption and scattered light in the desired spectral region. The geometric shape of these coated cells is suitable especially for color measurements using fibers. The second kind of color sensors, consisting of miniaturized photoelectric cell arrays and three different micro-patterned interference filter arrays, arranged on a glass substrate, make it possible to distinguish and measure colors with a local resolution. The honey-comb-arrangement of filter- and receiver cells and a flexible setup also permits a fast adaptation to different applications. In this paper design and development of both miniaturized interference filers are described. The different manufacturing procedures are depicted, advantages and questions arising with the employment of interference filters are discussed and the entire assembly of both sensors is presented.

Design and fabrication of miniaturized dielectric interference coatings (1999)

Marcus Frank, Norbert Kaiser, Uwe B. Schallenberg
SPIE Proceedings Volume 3738: Advances in Optical Interference Coatings, Claude Amra; H. Angus Macleod, Editors, pp.502-510

Miniaturized interference filters were designed and fabricated using three different manufacturing technologies. Applying micro-milled ceramic masks during the coating processes different arrays of interference filters with 1 mm lateral feature size were arranged on a 3-inch Si-substrate. The spectral sensitivity of receiver cells has been modified by direct coating using ion assisted deposition (IAD) at low temperature. IAD-processes also allow the application of microlithographic masks, which are removable by organic solvents after the deposition process. As an example three different miniaturized interference filters were arranged side by side with lateral filter dimensions of a few tens of microns. A combination of coating processes, microlithographic masking procedures, and reactive ion etching made it possible to arrange three different stripe filters with minimum filter features of about 5 micrometers side by side.

Spectral-sensitive on-chip masking of Si-PIN-diodes using patterned and self-blocked optical coatings (2000)

Uwe B. Schallenberg, Stefan Jakobs, Wolfgang Buss
SPIE Proceedings Volume 4094: Optical and Infrared Thin Films, Michael L. Fulton, Editors, pp.1-6

The manufacturing processes for spectral-sensitive on-chip masking of Si-PIN-diodes using thin-film optical filters are described. As two examples, a diode array with red, green, and blue filters (RGB) and a UV-sensitive diode are explained in detail. The RGB-filters are made of TiO2SiO2 thin-films and the UV-filter is a metal/dielectric multilayer using HfO2, SiO2, and Al thin-films. Both filter types are self-blocked over a wavelength range from 200 to 1100nm. The optical coatings on the diodes are arranged as pixels with rhombic or rectangular shapes and with a later dimensions of about 20 microns as minimum. The used lift-off technique for patterning the coatings is described briefly. Reactive e-beam evaporation with ion-assistance is used to deposit the optical coatings.

 


Components & Applications

Dielektrischer Spiegel (Patent 1987)

DD 000000292725 A5
Anmeldedatum: 02.07.1987
Veröffentlichungsdatum: 08.08.1991
Hauptklasse: G02B 1/10
Erfinder: Dummernix, Erich; Pfeiffer, Peter; Schallenberg, Uwe; Wurlitzer, Gottfried
Anmelder: CARL ZEISS JENA GMBH
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Graded reflectance mirror design with unconventional profile for excimer laser (1994)

U. B. Schallenberg, H. Uhlig, N. Kaiser
Pure Appl. Opt. 3, 427-434

Very high damage threshold Al2O3/SiO2 dielectric coatings for excimer lasers (1994)

Norbert Kaiser, Hein Uhlig, Uwe B. Schallenberg, Bernhard Anton, Ute Kaiser, Klaus R. Mann, Eric Eva
SPIE Proceedings Volume 2114: Laser-Induced Damage in Optical Materials: Harold E. Bennett; Lloyd L. Chase; Arthur H. Guenther; Brian E. Newnam; M. J. Soileau, Editors, pp.325-334

In the EUREKA EU205 project the target products are industrial excimer lasers in the average power range of one kilowatt or more. The high power optical components and dielectric coatings have to be developed in close adaption to cavity design (optics), beam relay optics, mask imaging optics, and masks. Therefore, we used ultra low loss conventional e-beam evaporation for Al2O3/SiO2 dielectric multilayers. Based on a fundamental coating technique, both multilayer mean background absorption and absorption at localized spikes have been reduced drastically. The resulting KrF laser damage threshold of HR coatings is 16 J/cm2 (1-on-1, 30 ns, EMG-202-MSC). Measurements have been performed with an automated damage testing facility, being part of the EUREKA program. Multilayers have been characterized by Atomic Force Microscopy, Photothermal Microscopy, absorption measurements, and Spectroscopy of Sputtered Neutrals.
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High damage threshold Al2O3 dielectric coatings for excimer lasers (1995)

N. Kaiser, H. UHlig, U.B. Schallenberg, U. Kaiser, K. Mann
Thin Solid Films 260, 86-92

Thin-film plate polarizer with Fabry-Perot filter design (1996)

Uwe B. Schallenberg, Norbert Kaiser
SPIE Proceedings Volume 2776: Developments in Optical Component Coatings, Ian Reid, Editors, pp.336-341

Thin-film plate polarizers with a polarization ratio Tp/Ts > 1000 for single laser wavelengths can be realized if a Fabry-Perot filter is used. The spectral width of the polarization region of the filter polarizer is smaller than that of the usual long-wave pass filter, but there are not the practical difficulties of depositing multilayer systems with a large number of layers having nonquarter-wave thickness. For theoretical analysis, the principle of equivalent layer is extended to the Fabry-Perot design. Experimental results of the Fabry-Perot filter polarizer for different laser wavelengths, and with different coating materials, are presented.

Influence of the number of double layers on the damage threshold of Al2O3/SiO2 and LaF3/MgF2 mirrors at 248 nm (1996)


Eric Eva, Klaus R. Mann, Uwe B. Schallenberg, Norbert Kaiser, Rainer Henking, Detlev Ristau
SPIE Proceedings Volume 2714: 27th Annual Boulder Damage Symposium: Laser-Induced Damage in Optical Materials: 1995, Harold E. Bennett; Arthur H. Guenther; Mark R. Kozlowski; Brian E. Newnam; M. J. Soileau, Editors, pp.499-510

KrF-laser induced damage thresholds (LIDT) of HR stacks were investigated as a function of the number of quarterwave layers. The findings were interpreted in terms of calorimetric absorption measurements and scatter defect density counts as well as an analysis of the standing wave electric field. Higher numbers of high-purity Al2O3/SiO2 layers resulted in enhanced LIDT by shielding the substrate surface increasingly well. Contrary to this, LIDT decreased with increasing numbers of e-beam evaporated LaF3/MgF2 layers. This was accompanied by elevated absorptance, defect density and conditionability at higher stack numbers.

Damage-resistant thin film plate polarizer (1997)

Uwe B. Schallenberg, Norbert Kaiser
SPIE Proceedings Volume 2966: Laser-Induced Damage in Optical Materials: Harold E. Bennett; Arthur H. Guenther; Mark R. Kozlowski; Brian E. Newnam; M. J. Soileau, Editors, pp.243-249

A thin-film polarizer with a high polarization ratio for single laser wavelengths can be realized if a Fabry-Perot filter design is used.THe spectral width of the polarization region of the filter polarizer is smaller than that of the usual long-wave pass filter, but there are not the practical difficulties of depositing multilayer systems with a large number of layers having non-quarter-wave thicknesses. Experimental results of a HfO2/SiO2 Fabry-Perot filter polarizer at 355 nm are presented. The laser-induced damage thresholds of the polarizer are enhanced by minimizing E-field intensities and minimizing absorption.

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Filters

Dielektrischer Langpaßfilter für den ultravioletten Spektralbereich (Patent 1988)

DD 000000295933 A5
Anmeldedatum: 03.10.1988
Veröffentlichungsdatum: 14.11.1991
Hauptklasse: G02B 5/28
Erfinder: Huebelt, Ingrid; Jacob, Gertraud; Pfeifer, Peter; Schallenberg, Uwe; Wurlitzer, Gottfried
Anmelder: ZEISS CARL JENA GMBH
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Interferenzfilter (Patent 1994)

DE 000004442045 C2
Anmeldedatum: 25.11.1994
Veröffentlichungsdatum: 23.04.1998
Hauptklasse: G02B 5/28
Erfinder: Schallenberg, Uwe; Uhlig, Hein
Anmelder: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.

Hauptanspruch:
Interferenzfilter, bei dem in einer Cavity-Anordnung auf beiden Seiten einer Abstands-schicht (HA) Schichtenfolgen aus dielektrischen λ/4-Schichten (H, L) mit alternierend hohem und niedrigem Brechungsindex angeordnet sind und bei dem auf einer der beiden Seiten der Abstandsschicht (HA) in die Schichtenfolge dielektrischer Schichten asymmetrisch zur Abstandsschicht (HA) ein Stützsystem (S) aus mehreren in alternierender Folge jeweils aufeinander angeordneten dielektrischen und metallischen Schichten (M, L) eingefügt ist.
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Shift-free narrowband filters for the UV-B region (1996)

Hein Uhlig, Uwe B. Schallenberg, Norbert Kaiser
SPIE Proceedings Volume 2776: Developments in Optical Component Coatings, Ian Reid, Editors, pp.342-352

Monitoring of stratospherical ozone depletion by filter radiometers calls for narrowband filters with outstanding parameters. At filter wavelengths down to 300 nm narrow bandwidth, high peak transmittance together with high out- of-band blocking especially at longer wavelength are demanded. Furthermore, filters have to be completely free of wavelength shift caused by humidity. Conventional interference filters suffer from such shift because of the water sorption of the evaporated layers. By using plasma ion assisted deposition of zirconia and silica layers we succeeded in manufacturing blocked two-cavity filters with full width at half maximum of 1.7 nm and peak transmittance of 17 percent to NIR optical density is at least 6. There was no decrease in wavelength of such filters by changing relative humidity from 100 percent to 0 percent. Corresponding conventional filters shifted 4.5 nm under the same conditions. The filter performance achieved allows use for the development of sensitive and specific instrumentation for environmental, climate, and meteorological research.
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Advanced induced transmission filters for the UV and the visible range (2001)

U. Schallenberg and S. Jakobs
Optical Interference Coatings, OSA Technical Digest Series (Optical Society of America, 2001), paper TuB6

Designs of metal-dielectric bandpass filters and experimental results of such filters at 248 nm, 300 nm, and 500 nm are described. A new filter concept is discussed to realize patterned and directly on-chip coated bandpass filters.

High-precision longpass filter arrays for miniature spectrometers (2004)

Stefan Jakobs, Uwe B. Schallenberg
SPIE Proceedings Volume 5250: Advances in Optical Thin Films, Claude Amra; Norbert Kaiser; H. Angus Macleod, Editors, pp.663-669

Arrays of longpass filter coatings for high order suppression in miniature spectrometers were produced by plasma-ion assisted deposition and photolithogaphy. The filter edges were imaged by optical microscopy, scanning electron microscopy, and scanning force microscopy. Whereas a positioning accuracy of about 2 microns was achieved, the width of the filter edges varied between 2 and 10 microns.

Steep-edge filter design with equivalent layers (2005)

Uwe B. Schallenberg
SPIE Proceedings Volume 5963: Advances in Optical Thin Films II, Claude Amra; Norbert Kaiser; H. Angus Macleod, Editors, 59630A

Based on a special definition of the edge region of a thin-film interference filter, an approach to design steep-edge filters using the theory of equivalent layers is presented. Some features are discussed using the known theory to meet the topical filter requirements. An example is theoretically outlined and the spectral performance of a manufactured filter is presented.
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Comparison of gradient index and classical designs of a narrow band notch filter (2005)

Vesna Janicki, Marc Lappschies, Björn Görtz, Detlev Ristau, Uwe Schallenberg, Olaf Stenzel, Norbert Kaiser
SPIE Proceedings Volume 5963: Advances in Optical Thin Films II, Claude Amra; Norbert Kaiser; H. Angus Macleod, Editors, 59631O

Rugate structures, as well as gradient refractive index films in general, attract a lot of interest. The gradient index systems may provide advantages in both, optical performance and mechanical properties of the optical coatings. Rugates have shown to be especially interesting for design of notch filters. A lot of theoretical work on design of rugate filters has been done in the last decades. However, only few of the designs could be deposited, which is often caused by practical problems, e.g. preparing materials with the desired refractive index values. In this paper two different gradient refractive index designs are compared to a classical high-low stack. One gradient design is synthesized by an apodized sinusoidal structure that is approximated by homogeneous sublayers. The other one is based on an apodized sinusoidal structure as well, but it is approximated by a hybrid structure, i.e. a combination of linear gradient index ramps between the lowest and the highest refractive index applicable and homogeneous layers of high index values. The two gradient designs take into account the constraints posed by limitations of the real deposition systems. Both designs are compared to a classical high-low stack and the advantages and drawbacks of each approach are commented.
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Verfahren zur Herstellung multispektraler Filtergruppen sowie eine multispektrale Filteranordnung (Patent 2007)

DE 102007011112 A1
Anmeldedatum: 03.03.2007
Veröffentlichungsdatum: 04.09.2008
Erfinder: Fritsch, Holger; Schallenberg, Uwe;Voß, Burkart
Anmelder: Jena-Optronik GmbH, 07745 Jena, DE

Zusammenfassung:
Die Erfindung betrifft ein Verfahren zur Herstellung von multispektralen Filterbaugruppen, die aus mehreren separat beschichteten Filterelementen zusammengesetzt sind, sowie eine Filteranordnung für Zeilenkameras zur multispektralen Bildaufnahme, insbesondere für die Fernerkundung der Erde. Die Aufgabe der Erfindung, eine neue Möglichkeit zur Herstellung von mehrkanaligen multispektralen Filterbaugruppen zu finden, die das Fertigungs- und Kostenrisiko von kompakten multispektralen Filterbaugruppen auch bei zunehmender Anzahl der Spektralkanäle reduziert, wird erfindungsgemäß gelöst, indem Substratbarren (3) aus für die zu filternde Wellenlänge des jeweiligen Filterelements (4) geeignetem optischem Material zuerst durch beliebige Formgebungsverfahren und Bearbeitungsverfahren maßhaltig hergestellt und erst danach unterschiedlich beschichtet, nach ihrer spektralen Güte selektiert und abschließend in geeigneter Weise zusammengesetzt werden.
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High performance notch filter coatings produced with PIAD and magnetron sputtering (2008)

M. Scherer, U. Schallenberg, H. Hagedorn, W. Lehnert, B. Romanov, A. Zoeller
SPIE Proceedings Volume 7101: Advances in Optical Thin Films III, Norbert Kaiser; Michel Lequime; H. Angus Macleod, Editors, 71010I

For Notch Filters, Rugate designs with a small index contrast and apodisation are well known in the literature. The required deposition of gradient index layers or so called flip flop structures is very complicated and difficult to manufacture. Higher order H/L stacks of coating materials with high index contrast result in very thick layer stacks. In our approach we replace the second refractive index by equivalent layers consisting of H/L materials with high index contrast. This leads to a combination of thick (>100nm) and very thin layers. Stable coating processes with dense layers are strict requirements. Another challenge is the accurate thickness control of very thin layers in the nanometer range. Single notch filters were produced with PIAD and broad-band optical monitoring. The most challenging filters were demonstrated with magnetron sputtering and monochromatic optical monitoring. Some outstanding results of single and multiple notch filter coatings will be presented.
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Design and manufacturing of high-performance notch filters (2010)

Uwe Schallenberg, Beatrix Ploss, Marc Lappschies, Stefan Jakobs
SPIE Proceedings Volume 7739: Modern Technologies in Space- and Ground-based Telescopes and Instrumentation, Eli Atad-Ettedgui; Dietrich Lemke, Editors, 77391X

Rugate designs for the realization of notch filters are well known in the literature. The required deposition of gradient index layers is difficult to manufacture. In our approach we apply the equivalent index theory to replace the gradient index profile of a notch filter design. We produce single and multiple notch filters with plasma ion-assisted deposition and broad-band optical monitoring. As examples, a 500nm notch filter for the GREGOR telescope and a 589nm notch filter for the GALACSI instrument of the VLT are discussed. Additionally, a 4-line multiple notch filter and a 218nm notch filter made for fluorescence spectroscopy applications are presented.
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Exclusive examples of high-performance thin-film optical filters for fluorescence spectroscopy made by plasma-assisted reactive magnetron sputtering (2011)

M. Lappschies, U. Schallenberg, S. Jakobs
SPIE Proceedings Volume 8168: Advances in Optical Thin Films IV, Michel Lequime; H. Angus Macleod; Detlev Ristau, Editors, 81680Y

For more than four decades band-pass filters are important components of microscopes used for the fluorescence spectroscopy. During all the time this special field of application has been one of the main drivers for research and development in thin-film optics, particularly for the thin-film design software and the coating technology. With a shortwave pass filter, a multi-notch filter, and a classical band-pass filter as examples of such filters provided for the latest generation of fluorescence microscopes we present the state-of-the-art in coating design and technology. Manufacturing these filters is a great challenge because the required spectral characteristics need necessarily multilayers with up to 300 layers and overall thicknesses up to 30 μm. In addition, the designs require also 3 to 5 nm as thinnest layers and all the layers are completely of non-quarterwave type. The filters were manufactured in a rapid-prototyping regime by a Leybold Helios plant using plasma-assisted reactive magnetron sputtering of thin films of different metal oxides. Designed and real spectra are compared and differences are discussed. Measurement results of other optical and non-optical characteristics as film stress, total integrated scattering, and micro roughness are presented.
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Manufacturing and characterizing of all-dielectric band-pass filters for the short-wave infrared region (2011)

T. Bauer, M. Lappschies, U. Schallenberg, S. Jakobs
SPIE Proceedings Volume 8168: Advances in Optical Thin Films IV, , Michel Lequime; H. Angus Macleod; Detlev Ristau, Editors, 81680Z

Besides the typical channels in the visible and near infrared spectrum, optical remote sensing of the earth from air and space utilizes also several channels in the short-wave infrared spectrum from 1000 nm to 3000 nm. Thin-film optical filters are applied to select these channels, but the application of classical multiple-cavity band-pass filters is impossible. Because of their additional blocking elements they are disallowed due to geometrical or other non-optical reasons. Within the sensitivity region of an MCT detector as typical detector device, the selection and blocking of radiation by the filter has to be provided by a single multilayer system. The spectral region of the SWIR as well as blocking width and depth require necessarily designs with overall thicknesses of more than 20 μm, with layer numbers up to 100. SiO2 and TiO2 were used as thin-film materials deposited with reactive e-beam evaporation under ion assistance in a Leybold SyrusPro box coater. A special challenge was the thickness measurement of the thin films by an optical broadband monitoring device in the visible range. The results of manufacturing and characterizing of such filters are presented by three examples for the center wavelengths of 1375 nm, 1610 nm, and 2190 nm.
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