Stray light characterization with ultrafast time-of-flight imaging

AbstractUnderstanding stray light (SL) is a crucial aspect in the development of high-end optical instruments, for instance space telescopes. As it drives image quality, SL must be controlled by design and characterized experimentally. However, conventional SL characterization methods are limited as they do not provide information on its origins. The problem is complex due to the diversity of light interaction processes with surfaces, creating various SL contributors. Therefore, when SL level is higher than expected, it can be difficult to determine how to improve the system. We demonstrate a new approach, ultrafast time-of-flight SL characterization, where a pulsed laser source and a streak camera are used to record individually SL contributors which travel with a specific optical path length. Furthermore, the optical path length offers a means of identification to determine its origin. We demonstrate this method in an imaging system, measuring and identifying individual ghosts and scattering components. We then show how it can be used to reverse-engineer the instrument SL origins.

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Stray Light Characterization With Ultrafast Time-of-flight Imaging

10.21203/rs.3.rs-273690/v1 ◽

2021 ◽

Author(s):

Lionel Clermont ◽

Wilfried Uhring ◽

Marc Georges

Keyword(s):

Path Length ◽

Imaging System ◽

Time Of Flight ◽

Optical Path Length ◽

Optical Path ◽

Stray Light ◽

Laser Source ◽

Space Telescopes ◽

Characterization Methods ◽

Instance Space

Abstract Understanding stray light (SL) is a crucial aspect in the development of high-end optical instruments, for instance space telescopes. As it drives image quality, SL must be controlled by design and characterized experimentally. However, conventional SL characterization methods are limited as they do not provide information on its origins. The problem is complex due to the diversity of light interaction processes with surfaces, creating various SL contributors. Therefore, when SL level is higher than expected, it can be difficult to determine how to improve the system. We demonstrate a new approach, ultrafast time-of-flight SL characterization, where a pulsed laser source and a streak camera are used to record individually SL contributors which travel with a specific optical path length. Furthermore, the optical path length offers a means of identification to determine its origin. We demonstrate this method in an imaging system, measuring and identifying individual ghosts and scattering components. We then show how it can be used to reverse-engineer the instrument SL origins.

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PROCEDURE ENABLING SIMULATION AND IN-DEPTH ANALYSIS OF OPTICAL EFFECTS IN CAMERA-BASED TIME-OF-FLIGHT SENSORS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-2-83-2018 ◽

2018 ◽

Vol XLII-2 ◽

pp. 83-89

Author(s):

M. Baumgart ◽

N. Druml ◽

M. Consani

Keyword(s):

Path Length ◽

Time Of Flight ◽

Optical Path Length ◽

Optical Path ◽

Light Sources ◽

Simulation Approach ◽

Optical Signals ◽

Sensor Performance ◽

Depth Analysis ◽

Detailed Simulation

This paper presents a simulation approach for Time-of-Flight cameras to estimate sensor performance and accuracy, as well as to help understanding experimentally discovered effects. The main scope is the detailed simulation of the optical signals. We use a raytracing-based approach and use the optical path length as the master parameter for depth calculations. The procedure is described in detail with references to our implementation in Zemax OpticStudio and Python. Our simulation approach supports multiple and extended light sources and allows accounting for all effects within the geometrical optics model. Especially multi-object reflection/scattering ray-paths, translucent objects, and aberration effects (e.g. distortion caused by the ToF lens) are supported. The optical path length approach also enables the implementation of different ToF senor types and transient imaging evaluations. The main features are demonstrated on a simple 3D test scene.

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Design and Characterisation of a Fast Steering Mirror Compensation System Based on Double Porro Prisms by a Screw-Ray Tracing Method

Sensors ◽

10.3390/s18114046 ◽

2018 ◽

Vol 18 (11) ◽

pp. 4046 ◽

Cited By ~ 5

Author(s):

Yu-Hao Chang ◽

Chien-Sheng Liu ◽

Chih-Chun Cheng

Keyword(s):

Ray Tracing ◽

Path Length ◽

Degrees Of Freedom ◽

Optical Path Length ◽

Compensation System ◽

Optical Path ◽

Laser Source ◽

Ray Tracing Method ◽

Set Up ◽

Tracing Method

This study proposes a novel FSM compensation system for four degrees of freedom (DOF) laser errors compensation, which has the advantage of shorter optical path length, fewer elements and an easier set-up process, meaning that it can be used at different locations. A commercial software, Zemax, is used to evaluate the function of the proposed FSM compensation system and the mathematical modelling of the proposed FSM compensation system is established by using a skew-ray tracing method. Finally, the proposed FSM compensation system is then verified experimentally using a laboratory-built prototype and the result shows that the proposed FSM compensation system achieves the ability to compensate the 4 DOF of the laser source.

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Automatic Control of Optical Path Length for Improving Power of Pulse Fiber Lasers

IEEJ Transactions on Electronics Information and Systems ◽

10.1541/ieejeiss.139.113 ◽

2019 ◽

Vol 139 (1) ◽

pp. 113-118

Author(s):

Ryo Amano ◽

Minoru Yoshida

Keyword(s):

Automatic Control ◽

Fiber Lasers ◽

Path Length ◽

Optical Path Length ◽

Optical Path

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Investigation of particulate systems using optical pathlength spectroscopy

MRS Proceedings ◽

10.1557/proc-627-bb1.6 ◽

2000 ◽

Vol 627 ◽

Author(s):

Gabriel Popescu ◽

Aristide Dogariu

Keyword(s):

Path Length ◽

Random Media ◽

Michelson Interferometer ◽

Industrial Process ◽

Optical Path Length ◽

Industrial Applications ◽

Optical Path ◽

Interference Signal ◽

Optical Length ◽

Reference Mirror

ABSTRACTIn many industrial applications involving granular media, knowledge about the structural transformations suffered during the industrial process is desirable. Optical techniques are noninvasive, fast, and versatile tools for monitoring such transformations. We have recently introduced optical path-length spectroscopy as a new technique for random media investigation. The principle of the method is to use a partially coherent source in a Michelson interferometer, where the fields from a reference mirror and the sample are combined to obtain an interference signal. When the system under investigation is a multiple-scattering medium, by tuning the optical length of the reference arm, the optical path-length probability density of light backscattered from the sample is obtained. This distribution carries information about the structural details of the medium. In the present paper, we apply the technique of optical path-length spectroscopy to investigate inhomogeneous distributions of particulate dielectrics such as ceramics and powders. The experiments are performed on suspensions of systems with different solid loads, as well as on powders and suspensions of particles with different sizes. We show that the methodology is highly sensitive to changes in volume concentration and particle size and, therefore, it can be successfully used for real-time monitoring. In addition, the technique is fiber optic-based and has all the advantages associated with the inherent versatility.

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Measurement of the effective optical path length of diffusing integrating cavities using time-resolved spectroscopy

Applied Optics ◽

10.1364/ao.57.003519 ◽

2018 ◽

Vol 57 (13) ◽

pp. 3519 ◽

Cited By ~ 1

Author(s):

Xue Zhou ◽

Jia Yu ◽

Lin Wang ◽

Zhiguo Zhang

Keyword(s):

Path Length ◽

Optical Path Length ◽

Optical Path ◽

Time Resolved ◽

Time Resolved Spectroscopy ◽

Effective Optical Path Length

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Non-Traditional Applications of near Infrared Spectroscopy Based on the Optical Characteristic Models for a Biological Material Having Cellular Structure

Journal of Near Infrared Spectroscopy ◽

10.1255/jnirs.119 ◽

1998 ◽

Vol 6 (1) ◽

pp. 41-46 ◽

Cited By ~ 6

Author(s):

Satoru Tsuchikawa

Keyword(s):

Biological Material ◽

Path Length ◽

Cellular Structure ◽

Process Model ◽

Near Infrared ◽

Traditional Approach ◽

Nir Spectroscopy ◽

Optical Path Length ◽

Optical Path ◽

The Mean

Non-destructive measurements, based on near infrared (NIR) spectroscopy, on biological material with a cellular structure like wood require a non-traditional approach. We have developed new concepts to model the optical properties of a sample having cellular structure, for the illumination conditions of the spectrometer available to us. A set of optical models, which consisted of the directional characteristics models, the light-path models and the equivalent surface roughness model was proposed to clarify the behaviour of light propagation in a wood sample. Furthermore, the mean optical path length, which was derived by incorporating the nth power cosine model of radiant intensity into the diffusion process model in consideration of the parallel beam component of incident light, was calculated. By introducing the concept of equivalent sample thickness, compatible with the mean optical path length, into the Kubelka–Munk theory, generalised input/output equations for radiation were constructed. In this non-traditional application of NIR spectroscopy, these optical concepts make it possible to analyse both the physical condition and chemical composition of a biological material with a cellular structure.

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