Calibration of spatially modulated snapshot imaging polarimeter based on phase-shift interferometry.

The snapshot imaging polarimeters (SIPs) using spatial modulation have gained increasing popularity due to their capability of obtaining all four Stokes parameters in a single measurement. However, the existing reference beam calibration techniques cannot extract the modulation phase factors of the spatially modulated system. In this paper, a calibration technique based on a phase-shift interference (PSI) theory is proposed to address this issue. The proposed technique can accurately extract and demodulate the modulation phase factors through measuring the reference object at different polarization analyzer orientations and performing a PSI algorithm. Using the snapshot imaging polarimeter with modified Savart polariscopes as an example, the basic principle of the proposed technique is analyzed in detail. Subsequently, the feasibility of this calibration technique was demonstrated by a numerical simulation and a laboratory experiment. This work provides a different perspective for the calibration of a spatially modulated snapshot imaging polarimeter.

Demodulation of polarization information for a spatially modulated snapshot imaging polarimeter based on the coherent demodulation theory.

The snapshot imaging polarimeter (SIP) using spatial modulation can obtain all the Stokes parameters of the target through a single measurement. During demodulating of the polarization information of the target, the reference light calibration method is generally used, including a bandpass filter. In this work, a method to demodulate the target polarization information is proposed, which is based on the coherence demodulation theory. Additionally, this method includes a multiplier and a low-pass filter. Taking a spatially modulated SIP using modified Savart polariscopes as an example, a detailed theoretical analysis of the method is derived, and the computer simulation and experiments are carried out to verify the method's feasibility. To the best of our knowledge, this work provides a novel method for demodulating polarization information of spatially modulated SIPs.

Medical empirical research on forest bathing (Shinrin-yoku): a systematic review.

AIMS: This study focused on the newest evidence of the relationship between forest environmental exposure and human health and assessed the health efficacy of forest bathing on the human body as well as the methodological quality of a single study, aiming to provide scientific guidance for interdisciplinary integration of forestry and medicine. METHOD: Through PubMed, Embase, and Cochrane Library, 210 papers from January 1, 2015, to April 1, 2019, were retrieved, and the final 28 papers meeting the inclusion criteria were included in the study. RESULT: The methodological quality of papers included in the study was assessed quantitatively with the Downs and Black checklist. The methodological quality of papers using randomized controlled trials is significantly higher than that of papers using non-randomized controlled trials (p < 0.05). Papers included in the study were analyzed qualitatively. The results demonstrated that forest bathing activities might have the following merits: remarkably improving cardiovascular function, hemodynamic indexes, neuroendocrine indexes, metabolic indexes, immunity and inflammatory indexes, antioxidant indexes, and electrophysiological indexes; significantly enhancing people's emotional state, attitude, and feelings towards things, physical and psychological recovery, and adaptive behaviors; and obvious alleviation of anxiety and depression. CONCLUSION: Forest bathing activities may significantly improve people's physical and psychological health. In the future, medical empirical studies of forest bathing should reinforce basic studies and interdisciplinary exchange to enhance the methodological quality of papers while decreasing the risk of bias, thereby raising the grade of paper evidence.