Query: Confocal laser scanning holographic microscopy of buried structures

Candidate papers:

abstract: In this paper, we present a confocal laser scanning holographic microscope for the investigation of buried structures. The multimodal system combines high diffraction limited resolution and high signal to noise ratio with the ability of phase acquisition. The amplitude and phase imaging capabilities of the system are shown on a test target. For the investigation of buried integrated semiconductor structures, we expand our system with an optical beam induced current modality that provides additional structure sensitive contrast. We demonstrate the performance of the multimodal system by imaging the buried structures of a microcontroller through the silicon backside of its housing in reflection geometry.
author_names: Lena Schnitzler

Krisztian Neutsch

Falk Schellenberg

Martin R Hofmann

Nils Gerhardt
title: Confocal laser scanning holographic microscopy of buried structures.
venue: Applied optics
year: 2021

abstract: Abstract In this paper, we present different optical metrology approaches for the investigation of buried technical structures. Contactless, potentially fast and non destructive techniques such as optical beam induced current (OBIC) confocal laser scanning microscopy (CLSM) and digital holographic microscopy (DHM) are described. Their properties are illustrated by investigating the buried structures of a microcontroller.
author_names: Lena Goring

Markus Finkeldey

Falk Schellenberg

Carsten Brenner

Martin R Hofmann

Nils Gerhardt
title: Optical metrology for the investigation of buried technical structures
year: 2017

abstract: In the paper the advantages of two different microscopic techniques, namely digital holographic microscopy (DHM) and Confocal Laser Scanning Microscopy (CLSM) have been combined with the aim to investigate HeLa cell culture in terms of statistical analysis of area of subcellular structures of HeLa cells and related to them dry mass estimation. To assure the proper statistical representation of the cells both measurements comprised of multiple fields of view (FoVs) stitched together to form two FoVs with overlapping regions. The results suggest a strong linear correlation of nucleoli dry mass to their projection area, a result that is promising in terms of its biological relevance.
author_names: Piotr Stepien

Tytus Bernas

Wojciech Krauze

Hanna Sas-Nowosielska

Malgorzata Kujawinska
title: Multi modal quantitative analysis of HeLa cells using digital holographic microscopy and confocal laser scanning microscopy
venue: Speckle: International Conference on Speckle Metrology
year: 2018

abstract: Abstract. The tympanic membrane (TM) is an important hearing component that when ruptured causes severe hearing difficulty. It has been mainly characterized mechanically by measuring its displacements, vibration modes, impedance, and thickness. The objective of this research is to determine the relationship of the TM's thickness obtained with confocal laser scanning microscopy (with scans along the Z axis) with the magnitude of the TM's surface displacements measured with sound stimuli of 1.8, 5.2, and 12 kHz using digital holographic interferometry. In order to correlate the data, three regions of four healthy cats' TMs are studied, with a particular finding that the thickness is not the same in these regions and, among samples, a feature readily noticed in the magnitudes of the displacements. Through the relationship of the data from the TM's surface displacements with its thickness, it is now possible to confidently detect pathological changes in its structure by simply quantifying the magnitude of the former, a characteristic corroborated by the Pearson correlation coefficient (r)
author_names: Cynthia V Santiago-Lona

Maria del Socorro Hernandez-Montes

Mauricio Fernando Jurado Moreno

Valeria Piazza

Manuel de la Torre

Carlos Andres Perez-Lopez

Fernando Mendoza-Santoyo

Anaid Sierra

Jesus Esquivel
title: Tympanic membrane displacement and thickness data correlation using digital holographic interferometry and confocal laser scanning microscopy
venue: Optical Engineering
year: 2019

abstract: We present a high speed, phase sensitive, line scanning reflectance confocal interference microscope. We achieved rapid confocal imaging using a fast line scan camera and quantitative phase imaging using off axis digital holography on a 1D, line by line basis. In our prototype system, a He Ne laser ~1.2 mW) was used to demonstrate the principle of operation. Using a 20 kHz line scan rate (1024 pixels per line scan) we achieved a video rate frame rate of 20 Hz for 1024x500 pixel en face confocal images (20 MHz total pixel rate) By using an objective lens of a NA 0.65, we achieved an axial and lateral resolution of ~3.5 micrometers and ~0.8 micrometers, respectively. By z stack imaging of a custom silicon target with a stepped structure, we confirmed that the axial sectioning of the interference microscope is similar to that of a traditional line scan confocal microscope (our microscope with the reference arm blocked) The utility of phase sensitive holographic detection in line scan confocal was demonstrated in two ways. First, using a custom axial height phantom fabricated using chrome deposition, we demonstrated variations in phase corresponding to heights in the 100 nm range with a contrast to noise ratio of ~31 dB. Second, we demonstrate digital refocusing of an out of focus holographic image. The mechanism of confocality in our line scan system is 1D physical pinholing. Our ongoing work aims to add an additional mechanism of confocality by using low spatial coherence sources to impose interferometric pinholing.
author_names: Changgeng Liu

Sebastian Knitter

Zhilong Cong

Ikbal Sencan

Hui Cao

Michael A Choma
title: High speed line scanning confocal holographic microscopy for quantitative phase imaging (Conference Presentation)
venue: SPIE BiOS
year: 2016

abstract: Laser scanning confocal microscopy, advantageous as a non destructive spatial imaging technique, has been used to probe the internal photonic crystal lattice structure of micron scale core fluorescein labeled shell corona silica microspheres that had been crystallized within anisotropically etched relief patterns in the 100 surface of silicon wafers. Using this method it was possible to determine the three dimensional positioning of individual microspheres that had been allowed to self assemble within the confines of square and rectangular shaped pyramidal microwells with sub micron lateral and vertical spatial resolution. This methodology confirmed that microspheres underwent vectorial crystal growth in the form of a face centered cubic lattice inside the pyramidal microwells in which the 100 face of the photonic crystal was oriented parallel to the 100 surface of the silicon wafer. Furthermore it was feasible to visualize both external and internal defects buried within photonic crystal lattices in the planarized opal patterned chips.
author_names: Vladimir Kitaev

Sebastien Fournier-Bidoz

San Ming Yang

Geoffrey A Ozin
title: Internal photonic crystal lattice structures of planarized opal patterned chips probed by laser scanning confocal fluorescence microscopy
year: 2002

abstract: A novel colloidal model system is developed for the purpose of achieving simultaneous three dimensional (3D) confocal imaging and optical tweezing of impurity probe particles embedded in a dense material of colloidal host particles. First, the colloidal host particles are developed from 3 trimethoxysilyl propylmethacrylate (TPM) and the solvent mixture is tuned to match the refractive index and the density of the particles. A sedimentation diffusion equilibrium profile of the TPM particles was imaged in 3D to establish suitability of the system for 3D confocal laser scanning microscopy, and to study its phase behaviour and particle dynamics. Then, core shell particles, which consist of a high refractive index core and a TPM shell, are synthesised to be used as the impurities. The versatility of the two step coating procedure with TPM has been demonstrated on several core materials, and the optical properties of the core shell particle are established using digital holographic microscopy and their optical trapping strengths. Together with the TPM host particles, the core shell particles are shown to be suitable impurity probes in dense colloidal materials, as they can be manipulated using optical tweezers in all three dimensions, whilst the structure and dynamics of the surrounding host particles can be imaged simultaneously using fast confocal laser scanning microscopy. Subsequently, to demonstrate the capability of the TPM based colloidal model system, the depletion potential of a pair of core shell probe particles embedded in a sea of TPM host particles has been measured using optical tweezing. This is derived from comparing the direct pair potential between the core shell particles in a TPM refractive index matching solvent, and the potential of mean force for the core shell particles embedded in a dense fluid region of the TPM host particles. Direct visualisation of the liquid structures of the TPM host particles in the binary system around the probe particles has been linked to the form of the depletion potential, and its oscillatory nature as a function of the particle separation. Lastly, the formation of colloidal dumbbell particles is discussed. The dumbbell formation has been rationalised in terms of the total surface energy of droplet formation on spherical surfaces and the calculations are compared with experimental results from coating various seed particles with TPM. Using optically anisotropic dumbbell particles and tuning the refractive index of the dispersion medium, a preliminary two trap experiment has been conducted which shows unusual trapping behaviour when a time delayed feedback trapping trajectory has been applied.
author_names: Yanyan Liu
title: Colloidal particles for confocal microscopy and optical tweezing
year: 2017

abstract: Abstract The morphology, optical, spectroscopic and electrical characterization of mm long graphite pillars created by picosecond pulsed laser irradiation (l 800 nm and 1 kHz of repetition rate) buried in single crystal CVD diamond to be employed as electrodes in a 3D diamond detector, is reported. The array of graphitized columns 2.5 mm long, with a diameter of 10 mm consisted of two rows spaced by 110 mm with 12 pillars in each, which formed an interdigitated electrode structure embedded in the diamond crystal bulk. The presence of stressed regions along and between pillars were clearly shown with optical polarized microscopy, in a black field configuration. Confocal micro Raman and photoluminescence analysis has been employed to scan local stresses, both generated around the graphitic wires and also developed on the pillars' plane. Defected/stressed regions with diameter of the order of 10 mm surrounding the individual pillars was measured, and paired carbon interstitials (3H defects) were also revealed. For the investigated structure, detrimental effects induced by such structural defects, clearly produced by laser induced diamond graphite transition, as well as the presence of a relatively high voltage drop along the graphitized pillars related to their own geometry have been reflected on the charge carriers collection performances evaluated under MeV b particles. The creation of electronic active states within the diamond bandgap, as emphasized by spectral photoconductivity characterization, would play a fundamental role in lowering lifetime of generated carriers and then the detector collection efficiency. Indeed, states located in the middle of the diamond bandgap, acting as efficient recombination centers and decreasing the lifetime of generated carriers, drastically reduce the mean drift path of carriers and then the overall detector collection efficiency, as evaluated in the examined structure even at the highest applied voltages (up to 600 V)
author_names: A A Khomich

K K Ashikkalieva

A P Bolshakov

Taras Kononenko

Victor G Ralchenko

V I Konov

Pietro Oliva

Gennaro Conte

Stefano Salvatori
title: Very long laser induced graphitic pillars buried in single crystal CVD diamond for 3D detectors realization
year: 2018

abstract: Abstract Thin inorganic barrier films deposited on plastics are essential to provide protection from moisture and oxygen aided degradation while maintaining a flexible substrate. Mechanical bending of the barrier films, causes stress induced cracks that may lead to significant reduction or loss of barrier protection. In situ characterization of film cracking on the nanoscale, transparent, and conformal atomic layer deposited (ALD) thin films is challenging especially when these films are in a buried layer structure. We developed a technique that can inspect in real time the cracking of the stressed barrier films using laser scanning confocal microscopy. The in situ inspection avoids the inaccurate measurement of the crack onset strain associated with the crack "close up" phenomenon. SU8 cover coat is applied to form a buried ALD layer structure and in situ inspection demonstrates the cracking of the ALD film in real time underneath the cover coat. This technique is nondestructive, versatile, and allows rapid and large area inspection of different types of barrier films.
author_names: Yadong Zhang

Ronggui Yang

Steven M George

Yung-Cheng Lee
title: In situ inspection of cracking in atomic layer deposited barrier films on surface and in buried structures
year: 2011

abstract: Multi scan femtosecond laser writing has been used for the fabrication of high contrast buried channel waveguides in Neodymium doped YAG ceramics. The fabricated structures have been demonstrated to be capable of light confinement in the near infrared. Confocal fluorescence microscopy has been used to elucidate the femtosecond assisted modifications induced in the Nd:YAG network. Based on the obtained fluorescence images the mechanisms leading to the refractive index increment at the modified zone have been discussed. The near infrared laser properties of the fabricated structures have been also investigated. Since the pioneering work of Davis et al. direct laser writing (DLW) with subpicosecond pulses has become a well established and versatile technique for the microprocessing of transparent media for integrated optics applications. Because of its inherent advantage for three dimensional (3D) processing inside the bulk of substrates, ultrafast DLW has already been used for the straightforward demonstration of numerous photonic devices such as 3D photonic crystals, photonic lanterns, integrated gratings, and near field lenses. Ultrafast DLW has also been proved to be an almost universal technique for waveguide (WG) writing in almost any transparent material. Within the field of solid state lasers, Neodymium doped ceramic yttrium aluminum garnet (Nd:cYAG) is of special relevance. So far, the DLW process in Nd:YAG has been based on the direct creation of surface or volume damage, and on the use of the collateral strained regions as waveguide cores. Indeed, the fabricated structures were found to retain the outstanding spectroscopic properties of Neodymium ions in the as fabricated YAG ceramics. As a matter of fact the fabricated waveguides were found to be highly efficient laser sources. Most of the structures reported up to now were based on the refractive index changes produced by the combination of lattice damage at focus (refractive index decrease) and lattice compression in the surroundings of damage volumes (this yielding to a refractive index increment) This approach, although demonstrated to provide excellent results, has the main drawback that propagating radiation along the waveguides has a non negligible overlap with damage volumes leading to residual propagation losses. In addition, the stress based waveguides fabricated in Nd:cYAG were not able of optical confinement for wavelengths longer than 1300 nm. 8 cm 1 1.5 cm 1 P012
author_names: J Martinez de Mendibil

Antonio Benayas

Daniel Jaque

Ajoy Kar

Airan Rodenas

Eugenio Cantelar
title: Step index Nd:YAG ceramic buried channel waveguides fabricated by direct laser writing
year: 2015