Gunnar Ritt’s research while affiliated with Fraunhofer Institute of Optronics, System Technologies and Image Exploitation and other places

What is this page?


This page lists works of an author who doesn't have a ResearchGate profile or hasn't added the works to their profile yet. It is automatically generated from public (personal) data to further our legitimate goal of comprehensive and accurate scientific recordkeeping. If you are this author and want this page removed, please let us know.

Publications (45)


Optical limiting performance of nanoparticles in liquid and solid media
  • Conference Paper

September 2009

·

87 Reads

·

12 Citations

Proceedings of SPIE - The International Society for Optical Engineering

Stefanie Dengler

·

Gunnar Ritt

·

Bernd Eberle

We present our investigation of the optical limiting behaviour of different metal and semiconductor nanoparticles in liquid and solid media. Nonlinear transmission measurements were performed by the use of nanosecond laser pulses at 532 nm and 1064 nm. For the various nanoparticles in liquid media large differences in the limiting response were found. Foremost the solid state samples are promising in terms of laser protection devices.


Protection of optical systems against laser radiation

September 2009

·

116 Reads

·

27 Citations

Proceedings of SPIE - The International Society for Optical Engineering

Both the increasing use of laser devices on the battlefield and the misuse of laser devices in civil environments (e.g. dazzling of pilots during approach) necessitate laser protection devices. Conventional laser protection filters based on absorption or interference effects only work in narrow wavelength bands and are usually not neutral in colour. Thus, they are not appropriate for such scenarios. Optical power limiting devices based on nonlinear optical effects (nonlinear absorption, nonlinear refraction, induced scattering) were proposed to offer broadband laser protection without disturbing the visual colour impression. Usually, optical nonlinear materials are examined in laboratory setups which are different from realistic optical systems. We report on the integration of nonlinear laser protection devices into different optical systems to prove the performance of limiting for commonly used optical systems.


Wideband protection filter (WPF) integrated within optical systems

October 2008

·

57 Reads

·

2 Citations

Proceedings of SPIE - The International Society for Optical Engineering

G. Ritt

·

B. Eberle

·

·

[...]

·

Laser radiation may lead to permanent damage of the human eye when it is exposed to high power irradiation, especially when using magnifying optics such as binoculars, sights or periscopes. Into such an optical system we integrated a novel passive solid-state threshold-triggered Wideband Protection Filter (WPF) that blocks the transmission only if the power exceeds a certain threshold. At input powers below threshold, the filter has high transmission over the whole spectral band. However, when the input power exceeds the threshold power, transmission is decreased dramatically. We demonstrate the WPF integration within a typical optical system and the influence of system parameters on the protection capability of the filter.


Figure 1. Field experiment at WTD 91. The picture was taken from the position of the IR camera. The weather station is located on the left. Objects included a wooden mast, a medal mast, a brick wall, a wooden hut, a lattice mast as well as tarmac, gravel, concrete and bare earth surfaces. Dots mark the positions of thermistors. 
Figure 3. Some of the objects used for the observer experiments. From left to right: Trees, houses, cables, lattice masts, towers (images not to scale)
Figure 4: A selection of backgrounds used in the observer experiments. From left to right: Farmland, sky, homogenous (used as a stand-in for snow), forest Type A, forest Type B, grassland.
Figure 6. Observers during the experiments at the Bückeburg German Army Aviation School in October 2006.
Perception range prediction for IR pilot sight
  • Article
  • Full-text available

May 2008

·

144 Reads

·

2 Citations

Proceedings of SPIE - The International Society for Optical Engineering

The increasing use of IR pilot sight in helicopters calls for a reliable prediction of perception ranges for a variety of objects, especially those needed for orientation and those posing as a potential hazard, like power poles, masts, isolated trees etc. Since the visibility of objects in the IR depends mainly on the temperature differences between those objects and a given background and only marginally on illumination, range prediction techniques used for the visual range or light-amplified vision are only of very limited use. While range predictions based on the Johnson criterion do offer some insight into expected ranges, the inherently nominal nature of distance estimates thus obtained hampers their use for an actual field-deployable pre-flight consulting procedure. In order to overcome those limitations, long-term simultaneous measurements of relevant objects and background temperatures and weather data were carried out and used for temperature prediction from prevalent weather conditions. Together with a perception model derived from extensive observer experiments based on synthetic images of the UH Tiger Pilot Sight Unit we developed a perception range prediction package which is currently evaluated by the weather service of the Bundeswehr. We will present results from the observer experiments together with the derived perception models. These are then compared to actual perception ranges as obtained from flight experiments.

Download

Novel filter providing human eye and optical sensors protection from the visible into the IR

April 2008

·

49 Reads

·

12 Citations

Proceedings of SPIE - The International Society for Optical Engineering

We introduce into optical systems, susceptible to be interrupted or damaged from laser, novel passive solid-state threshold-triggered Wideband Protection Filter (WPF) that blocks the transmission only if the power exceeds a certain threshold. We present new protection capabilities of our latest filter composed of improved technology. The WPF can be readily used for protection of detectors, cameras, or eye safety.


Citations (37)


... There exists a potential risk that these images are maliciously intercepted by hackers during online transmission, leading to the unintended breaches of sensitive privacy information [22,23]. Harnessing large sized PSFs has shown great potential in mitigating the aforementioned safety hazards [24][25][26][27][28][29][30]. However, the increasing spatial size of PSF not only poses significant challenges for high-quality image restoration, but also reduces the utilization of sensor pixels, thereby diminishing the versatile of camera and limiting its field of view (FOV). ...

Reference:

OpSecureCam: optically enhanced secure camera via an engineering point spread function
Laser Protection via Jointly Learned Defocus and Image Reconstruction
  • Citing Preprint
  • January 2025

... There exists a potential risk that these images are maliciously intercepted by hackers during online transmission, leading to the unintended breaches of sensitive privacy information [22,23]. Harnessing large sized PSFs has shown great potential in mitigating the aforementioned safety hazards [24][25][26][27][28][29][30]. However, the increasing spatial size of PSF not only poses significant challenges for high-quality image restoration, but also reduces the utilization of sensor pixels, thereby diminishing the versatile of camera and limiting its field of view (FOV). ...

Development of a sensor hardened against laser damage independent of wavelength by off-focus imaging
  • Citing Conference Paper
  • November 2024

... 7 Research on laser dazzling of thermal infrared sensors is less common because visible and near-infrared lasers pose more immediate safety risks and are more prevalent in civilian life, driving more research in those areas. [8][9][10][11][12][13] The critical papers in mid-infrared laser dazzle stem from almost twenty years before in the research of Schleijpen and colleagues in the NATO SCI-139 research group. [14][15][16] However, the effects observed for the quantum detectors, whether visible or infrared, are based on the same physics and thus, exhibit similar trends. ...

Laser Safety—What Is the Laser Hazard Distance for an Electro-Optical Imaging System?

... In the military shooting training background, it was possible to find sixteen scientific publications ( [2], [8], [14], [15], [20], [24], [26], [30], [32], [38], [42], [43], [45], [47], [48], and [51]) in the last five years that address the application of virtual reality in this instructional activity (considering the Scopus and Web of Science (WoS) databases). Although there is this current discussion on the subject, the authors have not yet found any work that evaluates the application of a commercial Head-Mounted Display (HMD) in military pistol shooting training. ...

Simulating laser dazzling using augmented and virtual reality
  • Citing Conference Paper
  • September 2021

... Therefore, these possible health risks during free field usage must be quantified. The reflections from the target materials can evoke Nominal Ocular Hazard Distances (NOHD) amounting from meters up to several kilometers, depending on the material properties and laser parameters [13,33,34]. This can cause permanent eye and skin damage, as well as injury to operators [33]. ...

Laser safety assessments supported by analyses of reflections from metallic targets irradiated by high-power laser light

... Besides, there is a wide span of damage threshold in Table. 1, which is mainly due to different experimental scenarios (eg. 10 s irradiation time in Ref. [10] or single shot in most of the other references) and different criteria for the damage threshold. [16,17] Theoretically, the silicon-based camera is considered to have no response to 1550 nm. However, there have been reported cases of 1550 nm LiDAR burning out cameras. ...

Impact of threshold assessment methods in laser-induced damage measurements using the examples of CCD, CMOS, and DMD

... A simple model of laser eye glare together with calculations for laser safety applications based on newly defined maximum glare exposure (MDE) and nominal eye glare distance (NODD) values are presented in [44]. In this study, an intraocular scattering model Analogous enabling studies as for the eye dazzle effect were conducted for camera sensors [45]. ...

Correction: Ritt, G. Laser Safety Calculations for Imaging Sensors. Sensors 2019, 19, 3765

... In Figure 5, we can recognize how the MPE S and MDE S vary with distance. Following the curves starting from large distance values, the exposure limits are quite constant, which correspond to the minimum values as given by Equations (13) and (18). For closer distances from about~40 m to~4 m, the exposure limits increase strongly (for the given example) with the decreasing distance. ...

Estimation of Lens Stray Light with Regard to the Incapacitation of Imaging Sensors

... Within this context, lasers can be maliciously used to disrupt or permanently damage cameras in diverse scenarios such as autonomous vehicles and drones [3][4][5][6]. To protect imaging system from laser damage, previous studies have explored techniques including multi-channel spectral compensation [7], liquid crystal-based switchable optical devices [8], phase-change material optical limiters [9], metamaterials [10], and integration time adjustment [11]. Despite their contributions, current technologies based on limiting principles still encounter challenges in achieving instantaneous and high dynamic range laser protection while maintaining real-time imaging. ...

Use of complementary wavelength bands for laser dazzle protection
  • Citing Article
  • January 2020

Optical Engineering