Bandwidth-variable tunable optical filter unit for illumination and spectral imaging systems using thin-film optical band-pass filters

Hennig, Georg; Brittenham, Gary M.; Sroka, Ronald; Kniebühler, Gesa; Vogeser, Michael; Stepp, Herbert

doi:10.1063/1.4803003

Cited by 12 publications

(4 citation statements)

References 18 publications

(39 reference statements)

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“…This technique eliminates the autofluorescence background while retaining the porphyrin fluorescence emission. 1,2,28 Employing two laser diodes at 407 and 425 nm, it shows potential for field diagnosis while removing the need to wash the erythrocytes prior to ZnPP/heme ratio determination. In Fig.…”

Section: Noninvasive Methodsmentioning

confidence: 99%

Medical laser application: translation into the clinics

Sroka¹,

Stepp²,

Hennig³

et al. 2015

J. Biomed. Opt

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Medical laser applications based on widespread research and development is a very dynamic and increasingly popular field from an ecological as well as an economic point of view. Conferences and personal communication are necessary to identify specific requests and potential unmet needs in this multi- and interdisciplinary discipline. Precise gathering of all information on innovative, new, or renewed techniques is necessary to design medical devices for introduction into clinical applications and finally to become established for routine treatment or diagnosis. Five examples of successfully addressed clinical requests are described to show the long-term endurance in developing light-based innovative clinical concepts and devices. Starting from laboratory medicine, a noninvasive approach to detect signals related to iron deficiency is shown. Based upon photosensitization, fluorescence-guided resection had been discovered, opening the door for photodynamic approaches for the treatment of brain cancer. Thermal laser application in the nasal cavity obtained clinical acceptance by the introduction of new laser wavelengths in clinical consciousness. Varicose veins can be treated by innovative endoluminal treatment methods, thus reducing side effects and saving time. Techniques and developments are presented with potential for diagnosis and treatment to improve the clinical situation for the benefit of the patient.

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Section: Noninvasive Methodsmentioning

confidence: 99%

Medical laser application: translation into the clinics

Sroka¹,

Stepp²,

Hennig³

et al. 2015

J. Biomed. Opt

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“…The periodic helical structure of the CLC cell can be changed by various external stimuli such as heat, electric fields or magnetic fields [ 7 , 8 , 9 ]. Due to these characteristics, CLCs have been studied regarding the fabrication of optical devices for various applications such as liquid crystal displays (LCDs), dye lasers, notch filters, optical sensors and mirrors [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. However, when the CLC cell is inclined with respect to the incident beam the reflection band shifts to a shorter wavelength due to the Bragg condition and a higher order reflection band appears [ 12 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Second-Order Reflection Bands from a Cholesteric Liquid Crystal Cell Based on a Wavelength-Swept Laser

Ahn

Kim

et al. 2020

Sensors

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We report the results of an experimental study of the characterization of second-order reflection bands from a cholesteric liquid crystal (CLC) cell that depends on the applied electric field, using a wide bandwidth wavelength-swept laser. The second-order reflection bands around 1300 nm and 1500 nm were observed using an optical spectrum analyzer when an electric field was applied to a horizontally oriented electrode cell with a pitch of 1.77 μm. A second-order reflection spectrum began to appear when the intensity of the electric field was 1.03 Vrms/μm with the angle of incidence to the CLC cell fixed at 36°. The reflectance increased as the intensity of the electric field increased at an angle of incidence of 20°, whereas at an incident angle of 36°, when an electric field of a predetermined value or more was applied to the CLC cell, it was confirmed that deformation was completely formed in the liquid crystal and the reflectance was saturated to a constant level. As the intensity of the electric field increased further, the reflection band shifted to a longer wavelength and discontinuous wavelength shift due to the pitch jump was observed rather than a continuous wavelength increase. In addition, the reflection band changed when the angle of incidence on the CLC cell was changed. As the angle of incidence gradually increased, the center wavelength of the reflection band moved towards shorter wavelengths. In the future, we intend to develop a device for optical wavelength filters based on side-polished optical fibers. This is expected to have a potential application as a wavelength notch filter or a bandpass filter.

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“…The helical structure of CLCs is not only related to its material properties but is also a sensitive function of temperature, electromagnetic field, acoustic field, radiation field, and even biochemical sensing. Therefore, CLCs have been widely applied in sensor fields, especially biosensors [1][2][3][4][5][6][7]. The liquid crystalline state has become ubiquitously recognized in organisms, in which the helical structure of amphiphilic lipids from the plasma membrane is a natural composition containing a lyotropic liquid crystal structure.…”

Section: Introductionmentioning

confidence: 99%

Sensing Characteristics of Side-Polished Fiber Based on the Alterations in Helical Structure of Thermo-Sensitive Cholesteric Liquid Crystals

Han

Jiang

Guo³

2019

Crystals

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Cholesteric liquid crystals (CLCs) are sensitive to environmental temperature changes, and have been employed as a specific intermediary for biosensors. Considering the temperature-dependent structural changes of CLCs, this study aimed to determine the sensing properties of side-polished fibers (SPFs) after coating with CLCs. The experimental results demonstrated that, with regard to the transmitted spectrum, the loss peak of CLC-coated SPFs exhibited a positive linear relationship with temperature changes over a range of 20 to 50 °C. The linear correlation coefficient achieved 97.8% when the temperature increased by 10 °C, and the loss peak drifted by 12.72 nm. The reflectance spectrum of CLCs coated on the polished surface were obtained using optical fiber sensors. The feasibility of measuring the helical structure of CLCs was further verified using SPF transmission spectroscopy. The findings indicated that the transmitted spectrum of SPFs could be adopted to characterize the helical structure of CLCs, which lays a solid foundation for further study on SPF-based biosensors.

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Bandwidth-variable tunable optical filter unit for illumination and spectral imaging systems using thin-film optical band-pass filters

Cited by 12 publications

References 18 publications

Medical laser application: translation into the clinics

Medical laser application: translation into the clinics

Characterization of Second-Order Reflection Bands from a Cholesteric Liquid Crystal Cell Based on a Wavelength-Swept Laser

Sensing Characteristics of Side-Polished Fiber Based on the Alterations in Helical Structure of Thermo-Sensitive Cholesteric Liquid Crystals

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