scholarly journals Thermal Properties of Bayfol® HX200 Photopolymer

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5498
Author(s):  
Pierre-Alexandre Blanche ◽  
Adoum H. Mahamat ◽  
Emmanuel Buoye

Bayfol® HX200 photopolymer is a holographic recording material used in a variety of applications such as a holographic combiner for a heads-up display and augmented reality, dispersive grating for spectrometers, and notch filters for Raman spectroscopy. For these systems, the thermal properties of the holographic material are extremely important to consider since temperature can affect the diffraction efficiency of the hologram as well as its spectral bandwidth and diffraction angle. These thermal variations are a consequence of the distance and geometry change of the diffraction Bragg planes recorded inside the material. Because temperatures can vary by a large margin in industrial applications (e.g., automotive industry standards require withstanding temperature up to 125°C), it is also essential to know at which temperature the material starts to be affected by permanent damage if the temperature is raised too high. Using thermogravimetric analysis, as well as spectral measurement on samples with and without hologram, we measured that the Bayfol® HX200 material does not suffer from any permanent thermal degradation below 160°C. From that point, a further increase in temperature induces a decrease in transmission throughout the entire visible region of the spectrum, leading to a reduced transmission for an original 82% down to 27% (including Fresnel reflection). We measured the refractive index change over the temperature range from 24°C to 100°C. Linear interpolation give a slope 4.5×10−4K−1 for unexposed film, with the extrapolated refractive index at 0°C equal to n0=1.51. This refractive index change decreases to 3×10−4K−1 when the material is fully cured with UV light, with a 0°C refractive index equal to n0=1.495. Spectral properties of a reflection hologram recorded at 532 nm was measured from 23°C to 171°C. A consistent 10 nm spectral shift increase was observed for the diffraction peak wavelength when the temperature reaches 171°C. From these spectral measurements, we calculated a coefficient of thermal expansion (CTE) of 384×10−6K−1 by using the coupled wave theory in order to determine the increase of the Bragg plane spacing with temperature.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guangzhong Ma ◽  
Runli Liang ◽  
Zijian Wan ◽  
Shaopeng Wang

AbstractQuantification of molecular interactions on a surface is typically achieved via label-free techniques such as surface plasmon resonance (SPR). The sensitivity of SPR originates from the characteristic that the SPR angle is sensitive to the surface refractive index change. Analogously, in another interfacial optical phenomenon, total internal reflection, the critical angle is also refractive index dependent. Therefore, surface refractive index change can also be quantified by measuring the reflectivity near the critical angle. Based on this concept, we develop a method called critical angle reflection (CAR) imaging to quantify molecular interactions on glass surface. CAR imaging can be performed on SPR imaging setups. Through a side-by-side comparison, we show that CAR is capable of most molecular interaction measurements that SPR performs, including proteins, nucleic acids and cell-based detections. In addition, we show that CAR can detect small molecule bindings and intracellular signals beyond SPR sensing range. CAR exhibits several distinct characteristics, including tunable sensitivity and dynamic range, deeper vertical sensing range, fluorescence compatibility, broader wavelength and polarization of light selection, and glass surface chemistry. We anticipate CAR can expand SPR′s capability in small molecule detection, whole cell-based detection, simultaneous fluorescence imaging, and broader conjugation chemistry.


1990 ◽  
Vol 29 (3) ◽  
pp. 191 ◽  
Author(s):  
Takeshi Kato ◽  
Hiroaki Inoue ◽  
Yasushi Takahashi ◽  
Koji K. Ishida

1989 ◽  
Vol 157 ◽  
Author(s):  
T. Bremer ◽  
P.R. Ashley ◽  
R. Irmscher ◽  
Ch. Buchal

ABSTRACTSingle crystalline substrates of LiNb03 have been implanted with 48Ti ions at 200 keV and doses up to 4 × 1017 cm−2. The implants have been performed at wafer temperatures of 77 K, 300 K and 620 K. Immediate subsequent processing at 1273 K in wet oxygen ambient led to good epitaxial regrowth at all doses, if sufficient time was allowed. The maximum observed extraordinary refractive index change after regrowth Δne=0.04, indicating a solubility limit of 3.3×l021 Ti cm−3 corresponding to 18 % of Nb5+ replaced by Ti4+.


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