Showing papers on "Stray light published in 2023"
TL;DR: In this article , the influence of material surface treatment on stray light was studied; the stray light analysis and optimization of the whole link of light transmission were carried out, and targeted suppression measures such as front baffle, field stop, special structure baffle and reflective inner baffle were adopted.
Abstract: The wide-spectrum integrated imaging method can simultaneously obtain the spectral information of different spectral bands of the same target, which is conducive to the realization of the high-precision detection of target characteristics, and can simultaneously obtain more comprehensive elements such as the structure, shape, and microphysical parameters of the cloud. However, for stray light, the same surface has different characteristics at different wavelengths, and a wider spectral band means more complex and diverse sources of stray light, which renders the analysis and suppression of stray light more difficult. In this work, according to the characteristics of the visible-to-terahertz integrated optical system design scheme, the influence of material surface treatment on stray light was studied; the stray light analysis and optimization of the whole link of light transmission were carried out. For the sources of stray light in different channels, targeted suppression measures such as front baffle, field stop, special structure baffle, and reflective inner baffle were adopted. The simulation results indicate that when the off-axis field of view was greater than 10°. The point source transmittance (PST) of the terahertz channel is on the order of 10−4, the visible and infrared channels are less than 10−5, and the final terahertz PST was on the order of 10−8, while visible and infrared channels were lower than 10−11. Here, we present a method for stray light suppression based on conventional surface treatments for broadband imaging systems.
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TL;DR: In this article , the authors quantified the impact of spectral stray light on SIF retrieval using a high-resolution imaging spectrometer, and found that the effect of stray light contributions from the canopy and reference spectra could cancel out if obtained from the same instrument.
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TL;DR: In this paper , the on-orbit operation of the star sensor was simulated, and the signal to noise ratio (SNR) was used as the index and test parameter to evaluate its stray light suppression ability.
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TL;DR: In this article , a freeform telescope with an effective focal length of 84mm, a large numerical aperture of 0.25, and a wide field of view (FoV) of 20° was designed.
Abstract: Currently, the emission of greenhouse gases is one of humanity's leading threats. To accurately and efficiently measure greenhouse gas levels in the atmosphere, we must develop imaging spectrometer systems with larger numerical apertures (NAs). However, designing a telescope with a large NA is difficult in this system. This paper presents a design strategy for aperture expansion to create a freeform telescope with a large NA. We compared different off-axis reflective telescopes and chose the Korsch structure, which has obvious advantages because of its wide field of view (FoV), large NA, and low stray light. Moreover, based on the influence of the position of the freeform surface in the aberration correction, we propose to use a single freeform surface to reduce the cost and increase manufacturability. A freeform telescope with an effective focal length of 84 mm, a large NA of 0.25, and a wide FoV of 20° is successfully designed. The modulation transfer function of the system is better than 0.62, the maximum distortion is controlled to be less than 0.486%, and the incident angle of the beam on the image plane is less than 10°. The design result shows that the instrument has wide FoV, large NA, low stray light, and high performance. At the same time, the design strategy in this paper provides an effective method for the telescope design of the imaging spectrometer with a large NA.
1 citations
TL;DR: In this paper , the authors proposed a crosstalk suppression method based on a stop array to reasonably suppress the stray light in a microlens array system, which can aid in realizing fast beam deflection owing to the lateral displacement between arrays.
Abstract: The microlens array (MLA) system can aid in realizing fast beam deflection owing to the lateral displacement between arrays. The MLA system has the advantages of miniaturization and good functionality. However, during system operation, crosstalk beams are generated between each microlens array unit, introducing additional stray light, thus affecting the imaging contrast of the system. Therefore, this study uses the matrix operation method to trace the paraxial ray to trace the optical system and analyzes the generation mechanism of crosstalk stray light in the MLA system. Furthermore, this study proposes a crosstalk suppression method based on a stop array to reasonably suppress stray light. Finally, an example of an infrared array scanning infrared optical system is considered so as to verify the correctness and feasibility of the proposed crosstalk stray light suppression method. Therefore, this paper introduces the stray light suppression principle to guide the optical design process of the system, providing a theoretical basis for the design and analysis of the microlens array scanning and search system.
TL;DR: In this paper , the authors present lessons learned and various technical elements to consider for stray light (flare) testing of digital imaging systems, including the radiometric (e.g., brightness) and geometric qualities of the light source and setup.
Abstract: Stray light (also called flare) is any light that reaches the detector (i.e., the image sensor) other than through the designed optical path. Depending on the mechanism causing stray light, it can introduce phantom objects (ghosts) within the scene, reduce contrast over portions of the image, and effectively reduce system dynamic range. These factors can adversely affect the application performance of the camera and, therefore, stray light measurement is to be included in the upcoming IEEE-P2020 standard for measuring automotive image quality. The stray light of a camera can be measured by capturing images of a bright light source positioned at different angles in (or outside of) the camera’s field of view and then processing those captured images into metric images with associated summary statistics. However, the setup and light source can have a significant impact on the measurement. In this paper, we present lessons learned and various technical elements to consider for stray light (flare) testing of digital imaging systems. These elements include the radiometric (e.g., brightness) and geometric (e.g., size) qualities of the light source and setup. Results are to be presented at the conference.
TL;DR: In this article , a new polarized SHWFS (p-SHWFS) based on the principle of polarization imaging was proposed, which utilized the difference of state of polarization (SoP) between signal and stray light to improve the image contrast.
Abstract: Shack-Hartmann wavefront sensor (SHWFS) has been widely used in adaptive optics (AO) systems to detect phase distortion characteristics. In laser communication, target detection, vision optics and other application fields, the performance of SHWFS is affected by bright skylight and scattered light, which restricted the working ability of the AO system severely. Therefore, this paper proposes a new polarized SHWFS (p-SHWFS) based on the principle of polarization imaging, which utilize the difference of state of polarization (SoP) between signal and stray light to improve the image contrast. The p-SHWFS can be composed simply by a micro-lens array and a linear polarization camera. The camera uses four directional polarizing filters at 0°, 135°, 45° and 90° on every four pixels. Thus, the degree of linear polarization (DoLP) and angle of linear polarization (AoLP) for the incident wavefront can be analyzed, and the signal-to-background ratio (SBR) can be improved in some certain depending on the difference of SoP. In this paper, we introduce the basic principle of the p-SHWFS and validate the feasibility and accuracy improvement by numerical simulation and practical experiments. The experimental results show that the p-SHWFS can improve obviously the measurement accuracy under strong stray light when the difference of SoP exists. That may give us some initial reference to reduce the influence of stray light in laser communication, target detection, vision optics and other application fields.
06 Jul 2023
TL;DR: In this paper , a plug-and-play (PnP) algorithm was proposed to restore the object through scattering media under the non-darkroom environment, which is established via the generalized alternating projection (GAP) optimization framework, Fienup phase retrieval (FPR) method, and FFDNeT.
Abstract: Imaging through scattering media is a fascinating subject in the computational imaging domain. The methods based on speckle correlation imaging have found tremendous versatility. However, a darkroom condition without any stray light is required because the speckle contrast is easily disturbed by ambient light, which can lead to the reduction in object reconstruction quality. Here, we report a plug-and-play (PnP) algorithm to restore the object through scattering media under the non-darkroom environment. Specifically, the PnPGAP-FPR method is established via the generalized alternating projection (GAP) optimization framework, Fienup phase retrieval (FPR) method, and FFDNeT. The proposed algorithm is demonstrated experimentally and shows significant effectiveness and flexible scalability, which describe the potential for its practical applications.
TL;DR: In this paper , the authors describe the process through which stray light analysis should be performed in optical systems involving image slicers, and describe how to determine all ray paths, compute cross-talk on the pupil mirrors due to scattering, quantify the ghost images' intensity, and determine baffle positions.
Abstract: We describe the process through which stray light analysis should be performed in optical systems involving image slicers. We detail how scattering models should be used depending on how the image slicer assembly will be fabricated. Our work describes how to determine all ray paths, compute cross-talk on the pupil mirrors due to scattering, quantify the ghost images’ intensity, and determine baffle positions. In the example given, an ABg model is applied to all mirror arrays separately, before considering their contributions altogether. We also consider diffraction due to the image slicer’s narrow slice apertures, which contribute to unwanted light in the system by causing cross-talk on the pupil mirrors. Using Fourier optics, this quantity is computed and compared with cross-talk caused by scattering. Our work represents a useful asset for optical engineers who work on image slicer-based systems and want to analyze stray light, by providing a clear and exhaustive procedure to follow to obtain accurate estimates.
TL;DR: In this paper , the authors demonstrate a compact and long focal length imaging system for building detection, which relies on two groups of correction elements to correct aberrations in order to avoid the use of aspheres.
TL;DR: In this paper , a universal algorithm for designing a panoramic annular lens (PAL) system free from stray light is proposed, which allows designers to eliminate troublesome stray light paths by optimizing lens parameters at an early stage of optical design.
Abstract: In this work, a universal algorithm for designing a panoramic annular lens (PAL) system free from stray light is proposed. The impact of a given stray light path to the optical system could be estimated without running a full stray light analysis process, which allows designers to eliminate troublesome stray light paths by optimizing lens parameters at an early stage of optical design. A 360° ×(40°-100°) PAL system is designed and implemented to verify the proposed method. Simulation shows that the point source transmittance (PST) decreases by 2 orders of magnitude at a specific field-of-view (FoV) range after optimizing the system. Experimental results show perfect consistency with the simulation predictions, which indicate that two types of stray light are totally eliminated in the demonstrated system. This stray light analysis and suppression method provides a promising approach for the research and development of ultra-wide angle high performance optical systems.
23 Jan 2023
TL;DR: In this paper , a simple and effective stray light correction method based on automatic region division was designed to find the specific area affected by stray light and get the boundary of different regions.
Abstract: Stray light contamination is an important factor affecting the nighttime remote sensing image quality, especially affecting the quantitative application of low-light-level remote sensing data. VIIRS Day/Night Band(DNB) data is the most widely used nighttime low-light-level data in the world. However, the stray light contamination impacts the DNB sensor’s nighttime scenes. In this paper, we analyzed the characteristics of VIIRS DNB stray light and designed a simple and effective stray light correction method based on automatic region division. We preprocessed the data that meet certain solar zenith angle (SZA) requirements to obtain the true stray light data. An automatic region division method according to the SZA is designed to find the specific area affected by stray light and get the boundary of different region. Polynomial curve fitting based on least square method was used to get the mathematical model of the stray light. Then the mathematical model was used to do the stray light correction. We use the DNB northern hemisphere Earth view data to verify this method. Experimental result shows that the proposed method can effectively remove stray light and restore the surface information while preserving the radiation information.
TL;DR: In this article , the design method of a special-shaped aperture diaphragm and entrance baffle, black baffle surface testing, simulating, selection, and stray light suppression analysis process is presented.
Abstract: The space-agile optical composite detection (SOCD) system with a pointing mirror possesses flexible and fast response ability. Like other space telescopes, if the stray light is not properly eliminated, it may result in a false response or noise that floods the real light signal due to the low illuminance and large dynamic range of the target. The paper shows the optical structure layout, the decomposition of the optical processing index and roughness control index, the stray light suppression requirements, and the detailed stray light analysis process. The pointing mirror and ultra-long afocal optical path increase the difficulty of stray light suppression in the SOCD system. This paper presents the design method of a special-shaped aperture diaphragm and entrance baffle, black baffle surface testing, simulating, selection, and stray light suppression analysis process. The special-shaped entrance baffle has a significant effect on the suppression of stray light and reduced dependence on the platform posture of the SOCD system.
TL;DR: In this paper , a precise optical mockup of the ITER EC H&CD equatorial launcher (EL) is fabricated in order to experimentally verify the characteristics of 170 GHz beam transmission.
06 Jul 2023
TL;DR: Saviouk and Diémoz as discussed by the authors developed an algorithm for stray light correction based on the physics of the instrument response to stray light which adds light from longer wavelengths to shorter ones, which can also be used to improve other calculations: the sulphur dioxide column, the aerosol optical depth, the effective temperature of the ozone layer or any other products.
Abstract: Abstract. Brewer ozone spectrophotometers have become an integral part of the global ground-based ozone monitoring network collecting data since the early 1980s. The double monochromator Brewer version (MkIII) was introduced in 1992. With the Brewer hardware being so robust, both single and double monochromator instruments are still in use. The main difference between the single Brewers and the double Brewers is the much lower stray light in the double instrument. Laser scans estimate the rejection level of the single Brewers to be 10-4.5 while the doubles improve this to 10-8, virtually eliminating the effects of stray light. For a typical single monochromator Brewer, stray light leads to an underestimation of ozone of approximately 1 % at 1000 DU ozone SCD and can exceed 5 % at 2000 DU, while underestimation of sulphur dioxide reaches 30 DU when no sulphur dioxide is present. This is because even a small additional stray light at shorter wavelengths significantly reduces the slant ozone at large values. An algorithm for stray light correction based on the physics of the instrument response to stray light which adds light from longer wavelengths to shorter ones has been developed. The simple assumption is that count rates measured at any wavelength have a contribution from stray light from longer, and thus brighter, wavelengths because of the ozone cross-section gradient leading to a rapid change in intensity as a function of wavelength. Using the longest measured wavelength (320 nm) as a proxy for the overall brightness provides an estimate of this contribution. The sole parameter, in the order of 0.2 to 0.6 %, that describes the percentage of light at the longest wavelength to be subtracted from all channels is determined by matching ozone calculations from the single and the double monochromator Brewers. Removing this additional count rate from the signal mathematically before deriving ozone corrects for the extra photons scattering within the instrument that produces the stray light effect. Analysing historical data from co-located single and double monochromator Brewers can provide an estimate of how the stray light contribution changes over time in an instrument. The corrected count rates of the measured wavelengths can also be used to improve other calculations: the sulphur dioxide column, the aerosol optical depth, the effective temperature of the ozone layer or any other products. Also presented, is an initial analysis of signs consistent with the stray light effect in the double monochromator Brewers. A multi-platform code to correct the count rates for stray light and saving the corrected values in a new B-file for use with any existing Brewer data analysis software is available to the global Brewer user community at https://zenodo.org/record/8097039 (Savastiouk and Diémoz, 2023).
01 Jan 2023
TL;DR: In this paper , a cooperative learning model namely two stay-two stray is used to improve student achievement in social studies learning process, which is based on the innovation of the learning process which is still not quite right.
Abstract: This research is based on the innovation of the social studies learning process which is still not quite right so it has an impact on student achievement. For the improvement effort, a Cooperative Learning model namely two stay-two stray is used. This research uses qualitative and quantitative appro
TL;DR: In this article , the Fourier-space magneto-optical Kerr effect (MOKE) was used to map the intensity distribution for a wide range of incident and reflected wave vectors, in combination with fitting procedure of the light intensity maps to the analytical expression of the Kerr effect under linear approximation.
Abstract: The magneto-optical Kerr effect (MOKE) is widely exploited in laboratory-based setups for the study of thin films and nanostructures, providing magnetic characterization with good spatial and temporal resolutions. Due to the complex coupling of light with a magnetic sample, conventional MOKE magnetometers normally work by selecting a small range of incident wave-vector values, focusing the incident light beam to a small spot, and recording the reflected intensity at that angular range by means of photodetectors. Using this approach, additional methodologies and measurements are required for full vectorial magnetic characterization. Here, we computationally investigate a Fourier-space MOKE setup, where a focused beam ellipsometer using high numerical aperture optics and a camera detector is employed to simultaneously map the intensity distribution for a wide range of incident and reflected wave vectors. We employ circularly incident polarized light and no analyzing optics, in combination with a fitting procedure of the light intensity maps to the analytical expression of the Kerr effect under linear approximation. In this way, we are able to retrieve the three unknown components of the magnetization vector as well as the material' s optical and magneto-optical constants with high accuracy and short acquisition times, with the possibility of single-shot measurements. Fourier MOKE is thus proposed as a powerful method to perform generalized magneto-optical ellipsometry for a wide range of magnetic materials and devices.
TL;DR: Zhang et al. as mentioned in this paper proposed an accurate and highly robust method (ETH) for STL suppression of space surveillance telescope, which is called the enhanced top-hat transform.
Abstract: Wide field and long exposure time can effectively improve the ability of space surveillance telescope to detect weak space targets. However, this is easily affected by stray light, resulting in the effective target submerged in the background of stray light. Based on the basic theory of Mathematical morphology, this paper proposes an accurate and highly robust method (ETH) for stray light suppression of space surveillance telescope, which is called the enhanced Top-Hat transform. Firstly, we define the Generalized Top-Hat transform according to the traditional Top-Hat transform. Secondly, we improve the background estimation of the traditional opening, introduce the closing to realize the multi-scale micro adjustment, and analyze the influence of the multi-scale micro adjustment on the stray light suppression and space weak targets segmentation. Finally, we introduce the noise suppression factor to reduce the residual noise in the stray light. In the field experiment, the method can effectively eliminate the interference of stray light, and greatly improves the local signal-to-noise ratio of space targets. It also shows that in a very low signal-to-noise ratio, this method can accurately and effectively segment space weak targets, and has strong robustness.
TL;DR: In this paper , the authors measured the optical property of epoxy to calculate the Mie scattering effect and developed eight types of samples by changing the ratio in the absorber material, which can be used to mitigate the stray light of a millimeter wave telescope with any shapes.
Abstract: We recently developed and characterized an absorber for millimeter wavelengths. To absorb a millimeter wave efficiently, we had to develop a low reflection and high absorption material. To meet these requirements, we added polystyrene beads in the epoxy for multiscattering in the absorber. The typical diameter of polystyrene beads corresponded to the scale of Mie scattering for photon multiscattering in the absorber. The absorber consists of epoxy, carbon black, and expanded polystyrene beads. The typical size of the expanded polystyrene beads is consistent with the peak of a cross-section of Mie scattering to increase the mean free path in the absorber. By applying this effect, we successfully improved the absorber’s performance. In this paper, we measured the optical property of epoxy to calculate the Mie scattering effect. Based on the calculation results, we developed eight types of samples by changing the ratio in the absorber material. To compare the eight samples, we characterized the reflectance and transmittance of the absorber in a millimeter wavelength. The measured reflectance and transmittance of a 2 mm thick sample with optimized parameters are, respectively, less than 20% and 10%. We also measured the transmittance in a submillimeter wavelength. The measured transmittance is less than 1%. The shape of absorber can be modified for any shape, such as chip and pyramidal shapes. This absorber can be used to mitigate the stray light of a millimeter wave telescope with any shapes.
TL;DR: In this paper , a more refined assessment of the EC stray radiation interaction with ITER first wall and diagnostics has been described, following update of the diffuse stray radiation model and update of ITER ECRH&CD system optics parameters.
Abstract: The ITER ECRH&CD system is composed by 24 gyrotrons at 170 GHz that will deliver 20 MW at the plasma. Up to 6.7 MW will be injected in the empty vacuum vessel at the beginning of each plasma discharge to provide the gas breakdown. In that phase and when the plasma absorption is non ideal, a certain level of EC non-absorbed power, usually addressed as stray radiation, will be present. The EC stray radiation interaction with ITER first wall and diagnostics has been described in preliminary works. A more refined assessment is here described, following update of the diffuse stray radiation model and update of the launchers optics parameters. The optical design of the EC equatorial launcher has been entirely redesigned to optimize the power deposition and minimize interaction with the launcher structures. The updated parameters for the 24 launched beams are now available and have been used to estimate the interaction of the beams to be used for the breakdown phase with the tokamak structures. The preliminary stray radiation model described every opening of the tokamak as a “black” hole, that is a perfect power sink. Refining this crude description, using for the openings a “grey” hole model, provide a better agreement with benchmarks from other alternative models. Examples of stray radiation estimates performed for various ITER structures, systems and diagnostics are discussed.
TL;DR: In this paper , the effects of combined roughness, mirror contamination, and surface imperfections were considered and a unified physical scattering model was constructed to estimate the stray light of the telescope system.
Abstract: In the field of space optics, correct estimation of the amount of stray light is necessary to evaluate system performance and guide the selection of the correct design. Given the noise target of several picometers on distance measurements, this configuration is very sensitive to stray-light noise; thus, stray-light estimation is an important part of the design process. For complex optical systems, stray-light simulations can be performed by using specific optical analysis software (FRED, Tracepro, ASAP), which require expensive licenses and excessive computing time. Herein, we consider the effects of combined roughness, mirror contamination, and surface imperfections, construct a unified physical scattering model and simulate it. According to the analysis, the stray light of the telescope system is less than 1010 of the outgoing laser power.These considerations apply to various optical systems.
08 Feb 2023
TL;DR: In this paper , the authors presented the design method of special shaped aperture diaphragm and heterosexual entrance baffle, black baffle surface testing, simulating and selection, and stray light suppression analysis process.
Abstract: The space-agile optical composite detection system with pointing mirror possesses flexible and fast response ability. Just like other space telescopes, if the stray light is not properly eliminated, it may result in a false response or noise flooding the real light signal due to the low illuminance and large dynamic range of target. The paper shows the optical structure layout, the decomposition of the optical figure profile and roughness profile index, the stray light suppression requirements, and the detailed stray light analysis process. Pointing mirror and ultra-long afocal optical path increase the difficulty of stray light suppression in space-agile optical detection system. This paper will present the design method of special shaped aperture diaphragm and heterosexual entrance baffle, black baffle surface testing, simulating and selection, and stray light suppression analysis process. The special-shaped entrance baffle has a significant effect on the suppression of stray light, and reduced dependence on platform posture.
08 Feb 2023
TL;DR: In this article , the authors presented the design method of special shaped aperture diaphragm and heterosexual entrance baffle, black baffle surface testing, simulating and selection, and stray light suppression analysis process.
Abstract: The space-agile optical composite detection system with pointing mirror possesses flexible and fast response ability. Just like other space telescopes, if the stray light is not properly eliminated, it may result in a false response or noise flooding the real light signal due to the low illuminance and large dynamic range of target. The paper shows the optical structure layout, the decomposition of the optical figure profile and roughness profile index, the stray light suppression requirements, and the detailed stray light analysis process. Pointing mirror and ultra-long afocal optical path increase the difficulty of stray light suppression in space-agile optical detection system. This paper will present the design method of special shaped aperture diaphragm and heterosexual entrance baffle, black baffle surface testing, simulating and selection, and stray light suppression analysis process. The special-shaped entrance baffle has a significant effect on the suppression of stray light, and reduced dependence on platform posture.
15 Mar 2023
TL;DR: TOM as discussed by the authors is a multilayer hermetically sealed transparent module that can be embedded in the anterior surface of an eyeglass lens or removably attached thereto.
Abstract: NSR demonstrates two prototypes of Transparent Optical Module based on Micro OLED and Micro LED custom displays. Near eye Transparent Optical Module (TOM) will solve the challenge integrating the imaging module of today’s AR technologies into the design of everyday eyewear frames and optics by replacing the light engine and optical engine with a single multilayer hermetically sealed transparent module that can be embedded in the anterior surface of an eyeglass lens or removably attached thereto. The real image and the virtual image are viewed through the point of regard on the eyeglass lens. Optics employ active or passive micro lens arrays. TOM is a thin (<2mm), lightweight, and power efficient module. We are discussing eye box, image quality and management of stray light effects of TOM’s design.
28 Feb 2023
TL;DR: In this article , an automatic calibration algorithm is proposed to reduce the depth error caused by internal stray light in amplitude-modulated continuous wave (AMCW) coaxial scanning light detection and ranging (LiDAR).
Abstract: In this paper, an automatic calibration algorithm is proposed to reduce the depth error caused by internal stray light in amplitude-modulated continuous wave (AMCW) coaxial scanning light detection and ranging (LiDAR). Assuming that the internal stray light generated in the process of emitting laser is static, the amplitude and phase delay of internal stray light are estimated using the Gaussian mixture model (GMM) and particle swarm optimization (PSO). Specifically, the pixel positions in a raw signal amplitude map of calibration checkboard are segmented by GMM with two clusters considering the dark and bright image pattern. The loss function is then defined as L1-norm of difference between mean depths of two amplitude-segmented clusters. To avoid overfitting at a specific distance in PSO process, the calibration check board is actually measured at multiple distances and the average of corresponding L1 loss functions is chosen as the actual loss. Such loss is minimized by PSO to find the two optimal target parameters: the amplitude and phase delay of internal stray light. According to the validation of the proposed algorithm, the original loss is reduced from tens of centimeters to 3.2 mm when the measured distances of the calibration checkboard are between 1 m and 4 m. This accurate calibration performance is also maintained in geometrically complex measured scene. The proposed internal stray light calibration algorithm in this paper can be used for any type of AMCW coaxial scanning LiDAR regardless of its optical characteristics.
23 Jan 2023
TL;DR: In this article , the design and experimental verification of stray light suppression is also the key link in the design of aerospace optical remote sensor in orbit, and comprehensive simulation verification is carried out through the light path tracking method.
Abstract: The stray light is one of the main factors affecting the imaging quality of optical remote sensor. The design and experimental verification of stray light suppression is also the key link in the design of aerospace optical remote sensor. This article based on the development needs of aerospace cameras in orbit, the stray light suppression analysis and product assurance of imaging remote sensing cameras with RC configuration as the optical system (or main optical system) were studied in a quantitative way. First of all, the stay light characteristics of such cameras were revealed in a quantitative way, the design and addition of the optimal stray light suppression structures were completed, and comprehensive simulation verification was carried out through the light path tracking method. Secondly, in the design stage, in strict accordance with the control requirements of the development of aerospace remote sensing camera, the necessary and reasonable product guarantee control point is set up by PDCA cycle method. Finally, through laboratory stray light qualitative tasting and on-orbit verification, the full-link verification of camera stray light suppression is completed. This paper can provide a reference for stray light suppression design and process quality control of large-caliber optical remote sensors.
TL;DR: Wang et al. as mentioned in this paper proposed a shadowless projection mapping system for interactive applications in which a target surface is frequently occluded from a projector with a user's body, and they proposed a delay-free optical solution for this critical problem.
Abstract: This paper presents a shadowless projection mapping system for interactive applications in which a target surface is frequently occluded from a projector with a user's body. We propose a delay-free optical solution for this critical problem. Specifically, as the primary technical contribution, we apply a large format retrotransmissive plate to project images onto the target surface from wide viewing angles. We also tackle technical issues unique to the proposed shadowless principle. First, the retrotransmissive optics inevitably suffer from stray light, which leads to significant contrast degradation of the projected result. We propose to block the stray light by covering the retrotransmissive plate with a spatial mask. Because the mask reduces not only the stray light but the achievable luminance of the projected result, we develop a computational algorithm that determines the shape of the mask to balance the image quality. Second, we propose a touch sensing technique by leveraging the optically bidirectional property of the retrotransmissive plate to support interaction between the user and the projected contents on the target object. We implement a proof-of-concept prototype and validate the above-mentioned techniques through experiments.