Abstract

The optical scheme of a near-field dual-beam mode-mismatched thermal-lens detector for capillary electrophoresis with a crossed-beam configuration employing a multimode HeCd laser (325 nm) as an excitation source was optimized. It is shown that a multimode laser can be successfully used as an excitation source in thermal lensing with minimal deviations in thermal responses from Gaussian excitation sources. An equation for diffraction thermal-lens theory for near-field measurements is deduced, and the experimental results agree with the deduced equation. The temperature rise in the capillary was estimated, and the exponential decrease of the signal with time for static conditions and low flow velocities was explained. The optimum configuration of the detector from the viewpoint of the maximum sensitivity and beam sizes was found. The detector provides a significant improvement in the detection limits for model compounds absorbing at 325 nm (nitrophenols) compared to the results obtained with a commercial absorbance detector operating at the same wavelength.

Laser-induced fluorescence detector with a fiber-coupled micro GRIN lens for capillary electrophoresis

Oluwatosin O. Dada
Appl. Opt. 59(16) 4849-4855 (2020)

On-column refractive-index detection based on retroreflected beam interference for capillary electrophoresis

Yanzhuo Deng and Bincheng Li
Appl. Opt. 37(6) 998-1005 (1998)

Terahertz-capillary electrophoresis (THz-CE) for direct detection of separated substances in solutions

Keiko Kitagishi, Takayuki Kawai, Masayoshi Tonouchi, and Kazunori Serita
Opt. Mater. Express 14(2) 472-482 (2024)

Pulsed mode thermal lens effect detection in the near field via thermally induced probe beam spatial phase modulation: a theory

J. F. Power
Appl. Opt. 29(1) 52-63 (1990)

Laser-based refractive-index detection for capillary electrophoresis: ray-tracing interference theory

Beat Krattiger, Alfredo E. Bruno, H. Michael Widmer, Martial Geiser, and René Dändliker
Appl. Opt. 32(6) 956-965 (1993)