Properties of moire´ magnifiers

̈lkel, Reinhard Vo

doi:10.1117/1.601889

Cited by 32 publications

(5 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When AIBN was used instead of DMPD under the same reaction conditions, macromolecules were formed with yields and molar masses comparable to those in literature. 21 Another point worth mentioning is the competition between thermal decay of AIBN and thermolysis of the triazene groups 22 under the conditions needed for this kind of polyaddition. Since at higher temperatures the decomposition of certain particularly substituted triazenes occurs at a considerable rate, great care must be taken when chosing the reaction conditions.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Polysulfides Containing the Triazeno Group and Their Application as Photoresists in Excimer Laser Polymer Ablation

Nuyken¹,

Dähn²,

Ehrfeld³

et al. 1997

Chem. Mater.

View full text Add to dashboard Cite

Two bifunctional unsaturated monomers containing the photosensitive triazene group were synthesized and reacted with dithiols. A radical polyaddition afforded polysulfides which carry the photosensitive chromophores in their backbone. The molar masses reach up to 10 400 g/mol and the glass transitions range between -2 and 39 °C. With respect to their application as dry photoresists for excimer laser ablation, thermo-and photolytical decomposition of monomers and polymers were investigated. TGA measurements revealed that the polymers were stable up to 255 °C, slightly below those of the monomers (270 °C). For photolysis in solution observed by UV/vis spectroscopy, the triazene absorption vanished on a time scale of seconds. Pulsed laser patterning was performed at 193 nm and with PMMA as a reference system. The sensitivity of the resists to irradiation was higher for PMMA and also the structural precision seemed to be slightly better for the standard, both probably owing to the applied wavelength. In contrast, the amount of redeposited material and the roughness of the polymer surface could be improved by using the triazene-containing resists.

show abstract

Section: Resultsmentioning

confidence: 99%

Synthesis of Polysulfides Containing the Triazeno Group and Their Application as Photoresists in Excimer Laser Polymer Ablation

Nuyken¹,

Dähn²,

Ehrfeld³

et al. 1997

Chem. Mater.

View full text Add to dashboard Cite

show abstract

“…Generally, aliasing effects (e.g. wagon-wheel effect) occur when there is an unfit sampling of the signal, which results in a production of the reconstructed signal with different characteristics from the original ones (aliases), or between overlapping transparent objects ( moiré effect ) 18 .…”

Section: Discussionmentioning

confidence: 99%

The Bull’s Eye Pattern of the Tear Film in Humans during Visual Fixation on En-Face Optical Coherence Tomography

Napoli

Nioi

d’Aloja

et al. 2019

Sci Rep

View full text Add to dashboard Cite

The aim of the study was to define and characterize the optical behavior of the tear film during visual fixation in humans on en-face optical coherence tomography (OCT). We included 20 healthy participants, 60% female, aged from 25 to 42 years (33.05 ± 4.97 [mean ± SD]) and ten patients with severe dry eye, 50% female, aged from 26 to 42 years (33.7 ± 5.31). To perform high-resolution tear film imaging, participants were asked to gaze at the internal fixation point in the spectral-domain anterior segment OCT device, and meanwhile scanning session was executed at the following time-points after blinking: at the 2nd, 3rd, 4th, 5th, and 6th second. After one hour, OCT imaging was repeated (second session) by a different operator masked to the study to verify the reliability of results. During each measuring session, a pulse oximetry was used for continuously measuring the heart rate and oxygen saturation (SpO2%). A preliminary experiment was also performed to test the absence of geometric patterns from the anterior surface of a motionless artificial eye. OCT imaging showed a motionless, stable anterior surface of the artificial eye and in dry eye patients. Conversely, in the healthy participants of the study, a bull’s eye pattern of the tear film was detected by OCT at the 2nd, 3rd, 4th, 5th, and 6th second after blinking, respectively, in 45%, 60%, 45%, 60%, and 40% of OCT scans during the first session, and in 35%, 65%, 65%, 60%, and 35% of cases in the second session. Overall, a total of 200 OCT scans were performed in normal human population. A significant correlation was found between the novel tear film pattern and heart rate during the first and the second session (p < 0.01) in healthy eyes. Conversely, no correlation was revealed with SpO2%. Intraclass correlation (ICC) analysis for OCT imaging of the tear film revealed a statistically significant reproducibility of the results (ICC = 0.838; p < 0.01), indicating the high level of reliability of the method, independently of heart rate and SpO2% variables. There exists a novel, geometric pattern of the tear film during visual fixation detectable by en-face OCT, which is mainly evident as heart rate increases. Its discovery implies in turn the presence of a specific vibration (or imperceptible motion) of the tear film that, at present, is not recognized and corrected by the OCT software (in image postprocessing) unlike other eyeball movements.

show abstract

“…Behind each microlens a small image of the object is generated. As a result of the pitch difference between the MLA and pinhole array, p = p L − p P , a Moiré-magnified image [40] is obtained when the pinholes have different amounts of offset with respect to the microlenses sample the micro-images [41]. Each channel corresponds to one field angle in object space.…”

Section: Artificial Apposition Compound Eye Objectivementioning

confidence: 99%

“…Furthermore, they are both chosen in such a way that the focal plane of all cells with their different angles of incidence is fixed at the position of the paraxial image plane (figure 8). This leads to a planarized Moiré-magnified image [4,40,41] in the detector surface. A torus segment with two radii of curvature in perpendicular directions is the most appropriate 3D surface type for such an anamorphic lens.…”

Section: Design and Simulation Of The Artificial Apposition Compound Eyementioning

confidence: 99%

Micro-optical artificial compound eyes

Duparré¹,

Wippermann²

2006

Bioinspir. Biomim.

155

View full text Add to dashboard Cite

Natural compound eyes combine small eye volumes with a large field of view at the cost of comparatively low spatial resolution. For small invertebrates such as flies or moths, compound eyes are the perfectly adapted solution to obtaining sufficient visual information about their environment without overloading their brains with the necessary image processing. However, to date little effort has been made to adopt this principle in optics. Classical imaging always had its archetype in natural single aperture eyes which, for example, human vision is based on. But a high-resolution image is not always required. Often the focus is on very compact, robust and cheap vision systems. The main question is consequently: what is the better approach for extremely miniaturized imaging systems—just scaling of classical lens designs or being inspired by alternative imaging principles evolved by nature in the case of small insects? In this paper, it is shown that such optical systems can be achieved using state-of-the-art micro-optics technology. This enables the generation of highly precise and uniform microlens arrays and their accurate alignment to the subsequent optics-, spacing- and optoelectronics structures. The results are thin, simple and monolithic imaging devices with a high accuracy of photolithography. Two different artificial compound eye concepts for compact vision systems have been investigated in detail: the artificial apposition compound eye and the cluster eye. Novel optical design methods and characterization tools were developed to allow the layout and experimental testing of the planar micro-optical imaging systems, which were fabricated for the first time by micro-optics technology. The artificial apposition compound eye can be considered as a simple imaging optical sensor while the cluster eye is capable of becoming a valid alternative to classical bulk objectives but is much more complex than the first system.

show abstract

Properties of moire´ magnifiers

Cited by 32 publications

References 5 publications

Synthesis of Polysulfides Containing the Triazeno Group and Their Application as Photoresists in Excimer Laser Polymer Ablation

Synthesis of Polysulfides Containing the Triazeno Group and Their Application as Photoresists in Excimer Laser Polymer Ablation

The Bull’s Eye Pattern of the Tear Film in Humans during Visual Fixation on En-Face Optical Coherence Tomography

Micro-optical artificial compound eyes

Contact Info

Product

Resources

About