Temperature-Based Long-Term Stabilization of Photoacoustic Gas Sensors Using Machine Learning.

In this study, we address the challenge of estimating the resonance frequency of a photoacoustic detector (PAD) gas cell under varying temperature conditions, which is crucial for improving the accuracy of gas concentration measurements. We introduce a novel approach that uses a long short-term memory network and a self-attention mechanism to model resonance frequency shifts based on temperature data. To investigate the impact of the gas mixture temperature on the resonance frequency, we modified the PAD to include an internal temperature sensor.

Interferon alpha-2b treatment for exophytic nasal papillomas and human papillomavirus infection.

Objectives: Exophytic Sinonasal Papilloma (ESP) is a benign tumor of the sinonasal tract. Complete surgical excision by endoscopic surgery is the treatment of choice. However, a high recurrence rate (36% at 5-year follow-up) is associated with this method, which may indicate the presence of microorganisms such as Human Papillomavirus (HPV).

Signal Enhancement of a Differential Photoacoustic Cell by Connecting the Microphones via Capillaries.

Differential photoacoustic spectroscopy (DPAS) cells are usually excited on the first longitudinal ring mode, with a microphone situated in the middle of each of the two resonator tubes. However, it is known from other photoacoustic spectroscopy cell designs that connecting the microphones via a capillary can lead to signal enhancement. By means of finite element method (FEM) simulations, we compared such a photoacoustic spectroscopy (PAS) cell with a capillary to a DPAS cell with a capillary attached to each of the two resonators and showed that the behavior of both systems is qualitatively the same: In both the PAS and the DPAS cell, in-phase and anti-phase oscillations of the coupled system (resonator-capillary) can be excited.

Types of spectroscopy and microscopy techniques for cancer diagnosis: a review.

Cancer is a life-threatening disease that has claimed the lives of many people worldwide. With the current diagnostic methods, it is hard to determine cancer at an early stage, due to its versatile nature and lack of genomic biomarkers. The rapid development of biophotonics has emerged as a potential tool in cancer detection and diagnosis.

Application of machine learning and laser optical-acoustic spectroscopy to study the profile of exhaled air volatile markers of acute myocardial infarction.

Conventional acute myocardial infarction (AMI) diagnosis is quite accurate and has proved its effectiveness. However, despite this, discovering more operative methods of this disease detection is underway. From this point of view, the application of exhaled air analysis for a similar diagnosis is valuable.

Nanosecond optical parametric oscillator with midinfrared intracavity difference-frequency mixing in orientation-patterned GaAs.

We report on efficient midinfrared difference-frequency generation (DFG) in orientation-patterned GaAs by intracavity mixing the signal and idler pulses of a narrowband nanosecond optical parametric oscillator based on periodically poled . The maximum average DFG output power reached 215 mW at 8.15 µm for a repetition rate of 35 kHz.

Narrow-band periodically poled lithium niobate nonresonant optical parametric oscillator.

We report on a narrowband, nonresonant periodically poled lithium niobate (PPLN) optical parametric oscillator using a volume Bragg grating (VBG) as the spectral narrowing element. Pumping by a Nd:YVO laser at 1.06 μm, a maximum output power of 4.

Intracavity difference-frequency mixing of optical parametric oscillator signal and idler pulses in BaGaSe.

An overall quantum conversion efficiency of 7.8% is achieved by intracavity mixing the signal and idler of a 1.064 μm pumped Rb:PPKTP optical parametric oscillator in BaGaSe.

Widely tunable in the mid-IR BaGaSe optical parametric oscillator pumped at 1064 nm.

A BaGaSe nanosecond optical parametric oscillator (OPO) shows extremely wide idler tunability in the mid-IR (2.7-17 μm) under 1.064 μm pumping.

Rb:PPKTP optical parametric oscillator with intracavity difference-frequency generation in AgGaSe.

A 1.064 μm pumped Rb:PPKTP optical parametric oscillator (OPO) generates mid-IR radiation by intracavity mixing the resonant signal and idler waves in AgGaSe. The ∼6  ns pulses at ∼7  μm have an energy of 670 μJ at 100 Hz, equivalent to an average power of 67 mW.

Intracavity-pumped, cascaded AgGaSe₂ optical parametric oscillator tunable from 5.8 to 18 µm.

A AgGaSe2 nonlinear crystal placed in a coupled cavity is intracavity pumped by the ~1.85-µm signal pulses of a 1.064-µm pumped Rb:PPKTP doubly-resonant optical parametric oscillator (OPO) operating at a repetition rate of 100 Hz.

Screening of patients with bronchopulmonary diseases using methods of infrared laser photoacoustic spectroscopy and principal component analysis.

A human exhaled air analysis by means of infrared (IR) laser photoacoustic spectroscopy is presented. Eleven healthy nonsmoking volunteers (control group) and seven patients with chronic obstructive pulmonary disease (COPD, target group) were involved in the study. The principal component analysis method was used to select the most informative ranges of the absorption spectra of patients' exhaled air in terms of the separation of the studied groups.