Thermal lens spectrometry

1990 ◽  
Vol 333 (1628) ◽  
pp. 165-166
Keyword(s):  
Refractive Index ◽  
Thermal Lens ◽  
Radiative Decay ◽  
Local Heating ◽  
Refractive Index Change ◽  
Spectrophotometric Analysis ◽  
Thermal Lens Spectrometry ◽  
Interaction Volume ◽  
Beam Sample ◽  
Pinhole Aperture

Thermal lens spectrometry is a laser-based technique that can be used for extremely sensitive spectrophotometric analysis in nanolitre volumes of solutions. In thermal lens spectrometry (Jun Shen & Snook 1989 a) a laser is used to excite chromophores in solution. Non-radiative decay routes of the excited chromophore leads to local heating of the solvent which in turn leads to a refractive index change in the beam/sample interaction volume. For most solvents the change in refractive index with temperature is negative (— d n /d T )which causes the solution to behave as a diverging lens. For a gaussian beam profile this causes a reduction in beam intensity at the beam centre which can be monitored in the far field of the thermal lens using a pinhole aperture and photomultiplier detector.

scholarly journals Critical angle reflection imaging for quantification of molecular interactions on glass surface

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guangzhong Ma ◽  
Runli Liang ◽  
Zijian Wan ◽  
Shaopeng Wang
Keyword(s):  
Refractive Index ◽  
Small Molecule ◽  
Molecular Interactions ◽  
Glass Surface ◽  
Critical Angle ◽  
Dynamic Range ◽  
Refractive Index Change ◽  
Label Free ◽  
Index Change ◽  
Sensing Range

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.

Optical properties of benzene and derivatives by the single beam thermal lens technique

2017 ◽  
Vol 26 (02) ◽  
pp. 1750025 ◽  
Author(s):  
M. K. Biswas ◽  
P. K. Das ◽  
E. Hoque ◽  
S. M. Sharafuddin ◽  
S. K. Das ◽  
...  
Keyword(s):  
Thermal Lens ◽  
Continuous Wave ◽  
Refractive Index Change ◽  
Optical Nonlinearity ◽  
Index Change ◽  
Single Beam ◽  
Cw Laser ◽  
Ion Laser ◽  
Benzene Toluene ◽  
Long Pulse

The present work studies the optical nonlinearity exhibited by the material (for Continuous Wave (CW) laser or long pulse) due to the change in thermal properties of the material on illumination. Thermal lens (TL) technique has been used to measure the refractive index change due to the formation of TL along with other thermo-optic properties of the material in solution. A CW Ar-ion laser has been used as light source and the laser beam was chopped at 25[Formula: see text]Hz frequency to obtain 12[Formula: see text]ms pulse to observe the formation of the TL within the sample. The [Formula: see text] value have been calculated by the TL technique for Benzene, Toluene and Dimethylaniline (DMA) in toluene and Benzene. The [Formula: see text] value is found to be in the order of 10[Formula: see text] to 10[Formula: see text][Formula: see text]cm2[Formula: see text]W[Formula: see text].

InP-based optical switch module operating through carrier-induced refractive index change

1990 ◽  
Vol 29 (3) ◽  
pp. 191 ◽  
Author(s):  
Takeshi Kato ◽  
Hiroaki Inoue ◽  
Yasushi Takahashi ◽  
Koji K. Ishida
Keyword(s):  
Refractive Index ◽  
Optical Switch ◽  
Refractive Index Change ◽  
Index Change ◽  
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