Jan Hergesel

I am a PhD student and researcher at the Technical University of Liberec, Faculty of Mechatronics, Informatics, and Interdisciplinary Studies. I obtained my Ing. degree in 2024 and my Bc. degree in 2022 from the same faculty. My research focuses on flicker perception and measurement.

RESEARCH, TEACHING, or OTHER INTERESTS

Electrical and Electronic Engineering, Software

Scopus Publications

Flicker Visibility and Irritability Threshold Measurements
Leoš Kukačka, Jana Svobodová, Jakub Nečásek, Sára Svobodová, Jan Hergesel, Pascal Dupuis, Laurent Canale, Dominik Dušek, Michal Vik, Jan Meyer, Robert Stiegler, Jiří Drápela
IEEE Transactions on Industry Applications, 2026
The IEC flicker observer model, or light flickermeter, is an algorithm whose purpose is to assess the severity of flicker produced by artificial lighting. Historically, it was developed by extraction from the voltage flickermeter, and it is thus based on experiments with incandescent lamps. This paper is one in a series of papers focused on verifying the light flickermeter performance for LED light sources. Flicker perceptibility (visibility) and irritability thresholds are measured in conditions taking into account peripheral vision. A new flicker irritability threshold measurement procedure is presented. The data are then compared to the thresholds indicated by the light flickermeter. The paper presents a detailed and complete verification of the flickermeter thresholds both in terms of the flicker severity measure (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Pst) as well instantaneous flicker (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Pinst) and brings a comprehensive understanding of what these two quantities actually represent.
Flicker Visibility With Different Spectra of White Light
Leoš Kukačka, Jan Hergesel, Jakub Nečásek, Petr Bílek, Michal Vik, Robert Stiegler, Morteza Pourarab, Jan Meyer, Jiří Drápela
IEEE Transactions on Industry Applications, 2025
The standard flickermeter (voltage flickermeter) algorithm commonly used for the evaluation of flicker severity in current electromagnetic compatibility standards originates from the 1980s. It was developed to mimic irritation of an average human observer by flickering incandescent lamp as a reference light source and optimized to voltage fluctuations caused by arc furnaces. However, the algorithm is questionable as the situation in the grid changed since the 1980s; many modern devices are being connected to the grid, creating voltage distortion patterns which are not properly recognized by the voltage flickermeter. In addition, incandescent lamps have been largely replaced by discharge lamps and later by LEDs. Transitioning the algorithm from incandescent lamp light to LED light requires detailed revision of every part of the algorithm. This paper is concerned with verifying the frequency weighting function of the average human observer which is one of the bases of the voltage flickermeter, as well as of the derived light flickermeter. Flicker sensitivity of 34 human observers is measured with two different light sources (LED warm and neutral white, incandescent lamp) and compared with the frequency weighting function used in the current specification of the flickermeters in standards. Finally, an optimization of the weighting function is proposed based on the findings.
Critical Flicker Frequency and Auditory Stimuli - Procedure Settings
Leoš Kukačka, Michaela Chmelařová, Jan Hergesel, Pascal Dupuis, Georges Zissis
IEEE Transactions on Industry Applications, 2024
The standing standardized measure for the assessment of flicker severity, the light flickermeter (IEC TR 61547-1:2020), evaluates the flicker irritability level in reference conditions as a necessary simplification. This misestimates the actual level in the presence of other factors known to influence flicker visibility. One such factor is noise, which interacts with the visual system under specific circumstances. However, direct effect of noise or any auditory stimuli on the flicker visibility threshold is not yet understood. This article is concerned with the design of experiments aimed at determining whether the critical flicker frequency (CFF) is subject to change when the observer is exposed to pulsating sounds. The article describes the work done in designing the experiments and also reveals data from a preliminary campaign. Data collected so far are insufficient to establish a direct link between pulsating sound and CFF, but are used to adjust the conditions of a wider campaign. Mathematical tools are developed to evaluate the experiment results using a probabilistic framework.
Comparison of Procedures for Measuring the Temporal Contrast Sensitivity Function
Leoš Kukačka, Jan Hergesel, Jakub Nečásek Petr Bílek, Michal Vik, Jan Meyer, Robert Stiegler, Jiří Drápela
2023 IEEE Sustainable Smart Lighting World Conference and Expo Ls18 2023, 2023
The IEC voltage flickermeter and light flickermeter are algorithms used to estimate the severity of flicker produced by artificial lighting systems. The algorithm was developed around incandescent lamps. In an effort to revise and update the algorithm to be compatible also with LED lamps, the flicker sensitivity curve needs to be verified with white light produced by LEDs, which have a distinct spectrum.This paper is concerned with comparing two distinct approaches to measure the flicker sensitivity of human observers. Traditionally, the flicker sensitivity (Temporal Contrast Sensitivity Function – TCSF) is measured by the Method of Adjustments, where the observer adjusts the stimulus intensity until they are satisfied with finding the flicker visibility threshold. In this paper, the method is compared to Two Alternative Forced Choice tests driven by a dynamic QUEST algorithm in terms of accuracy, speed, friendliness towards the observer, and the information yield in general.
Flicker Visibility with Different Spectra of White Light
Leoš Kukačka, Jan Hergesel, Jakub Nečásek, Petr Bílek, Michal Vik, Jan Meyer, Robert Stiegler, Morteza Pourarab, Jiří Drápela
2023 IEEE Industry Applications Society Annual Meeting IAS 2023, 2023
The standard flickermeter algorithm commonly used for the evaluation of flicker severity in current electromagnetic compatibility standards originates from the 1980s. It was developed with an incandescent lamp as a reference light source and optimized to voltage fluctuations caused by arc furnaces. However, the algorithm is questionable as the situation in the grid changed since the 1980s; many modern devices are being connected to the grid, creating voltage distortion patterns which are not properly recognized by the flickermeter. Moreover, incandescent lamps have been largely replaced by LEDs and discharge lamps. Transitioning the algorithm from incandescent lamp light to LED light requires detailed revision of every part of the algorithm, This paper is concerned with verifying the frequency weighting function which is a basis of Block 3 of voltage flickermeter and Block B of light flickermeter. Flicker sensitivity of over 30 human observers is measured with two different light sources (warm and neutral white) and compared with the frequency weighting function used in the current standards.
Critical Flicker Frequency and Auditory Stimuli-Procedure Settings
Leos Kukacka, Michaela Chmelarova, Jan Hergesel, Pascal Dupuis, Georges Zissis
Conference Record IAS Annual Meeting IEEE Industry Applications Society, 2022
This paper concerns with the design of experiments aimed at determining whether the critical flicker frequency (CFF) is subject to change when the observer is exposed to pulsating sounds. The paper describes the work done in designing the experiments and also reveals data from a preliminary campaign. Data do not form a basis to prove a direct link between pulsating sound and CFF, but can be used to better adjust the conditions before the full campaign.

RECENT SCHOLAR PUBLICATIONS

Flicker Visibility and Irritability Threshold Measurements
L Kukacka, J Svobodova, J Necasek, S Svobodova, J Hergesel, P Dupuis, ...
IEEE Transactions on Industry Applications , 2025
2025.0
Citations: 2
Interpretation of Flicker Severity Metrics Produced by the Light Flickermeter
L Kukačka, J Hergesel, J Drápela, J Meyer, R Stiegler, J Nečásek
CIE Midterm Meeting, Vienna , 2025
2025.0
Coherence of Flicker Visibility and Perceptibility Threshold Definitions by CIE and IEC
J Hergesel, L Kukačka, J Drápela, J Meyer, R Stiegler, J Nečásek
CIE Midterm Meeting, Vienna , 2025
2025.0
Flicker visibility with different spectra of white light
L Kukačka, J Hergesel, J Nečásek, P Bílek, M Vik, R Stiegler, M Pourarab, ...
IEEE Transactions on Industry Applications , 2025
2025.0
Citations: 6
Critical Flicker Frequency and Auditory Stimuli – Procedure Settings
L Kukačka, M Chmelařová, J Hergesel, P Dupuis, G Zissis
IEEE Transactions on Industry Applications 60 (1), 1938-1945 , 2023
2023.0
Citations: 3
Comparison of Procedures for Measuring the Temporal Contrast Sensitivity Function
L Kukačka, J Hergesel, P Bílek, J Nečásek, M Vik, J Meyer, R Stiegler, ...
2023 IEEE Sustainable Smart Lighting World Conference & Expo (LS18), 1-6 , 2023
2023.0
Citations: 5
Critical Flicker Frequency and Auditory Stimuli - Procedure Settings
L KUKAČKA, M CHMELÁŘOVÁ, J HERGESEL, P DUPUIS, G ZISSIS
IEEE Industry Applications Society Annual Meeting , 2022
2022.0
Citations: 2
Comparison of Procedures for Measuring the Temporal Contrast Sensitivity Function
L KUKAČKA, J HERGESEL, J NEČÁSEK, P BÍLEK, VIK Michal, J MEYER
2023 IEEE Sustainable Smart Lighting World Conference & Expo (LS18), 1-6 , 0
Citations: 2
Řídicí program pro experiment na měření prahu viditelnosti f likru na klasických žárovkách
J Hergesel
Technical University of Liberec , 0
Realizace Experimentů pro měření vjemu flikru u žárovek
J Hergesel, J Nečásek, P Bílek, L Kukačka

MOST CITED SCHOLAR PUBLICATIONS

Flicker visibility with different spectra of white light
L Kukačka, J Hergesel, J Nečásek, P Bílek, M Vik, R Stiegler, M Pourarab, ...
IEEE Transactions on Industry Applications , 2025
2025.0
Citations: 6
Comparison of Procedures for Measuring the Temporal Contrast Sensitivity Function
L Kukačka, J Hergesel, P Bílek, J Nečásek, M Vik, J Meyer, R Stiegler, ...
2023 IEEE Sustainable Smart Lighting World Conference & Expo (LS18), 1-6 , 2023
2023.0
Citations: 5
Critical Flicker Frequency and Auditory Stimuli – Procedure Settings
L Kukačka, M Chmelařová, J Hergesel, P Dupuis, G Zissis
IEEE Transactions on Industry Applications 60 (1), 1938-1945 , 2023
2023.0
Citations: 3
Flicker Visibility and Irritability Threshold Measurements
L Kukacka, J Svobodova, J Necasek, S Svobodova, J Hergesel, P Dupuis, ...
IEEE Transactions on Industry Applications , 2025
2025.0
Citations: 2
Critical Flicker Frequency and Auditory Stimuli - Procedure Settings
L KUKAČKA, M CHMELÁŘOVÁ, J HERGESEL, P DUPUIS, G ZISSIS
IEEE Industry Applications Society Annual Meeting , 2022
2022.0
Citations: 2
Comparison of Procedures for Measuring the Temporal Contrast Sensitivity Function
L KUKAČKA, J HERGESEL, J NEČÁSEK, P BÍLEK, VIK Michal, J MEYER
2023 IEEE Sustainable Smart Lighting World Conference & Expo (LS18), 1-6 , 0
Citations: 2
Interpretation of Flicker Severity Metrics Produced by the Light Flickermeter
L Kukačka, J Hergesel, J Drápela, J Meyer, R Stiegler, J Nečásek
CIE Midterm Meeting, Vienna , 2025
2025.0
Coherence of Flicker Visibility and Perceptibility Threshold Definitions by CIE and IEC
J Hergesel, L Kukačka, J Drápela, J Meyer, R Stiegler, J Nečásek
CIE Midterm Meeting, Vienna , 2025
2025.0
Řídicí program pro experiment na měření prahu viditelnosti f likru na klasických žárovkách
J Hergesel
Technical University of Liberec , 0
Realizace Experimentů pro měření vjemu flikru u žárovek
J Hergesel, J Nečásek, P Bílek, L Kukačka