Narcissus Effect Research Articles

Thin lens narcissus model in infrared lens design with cooled detectors.

A mathematical model of the narcissus effect in infrared lenses with cooled detectors is discussed. The proposed model enables optical designers to take the narcissus performance of infrared lenses into consideration in the thin lens predesign stage. Third order thin lens aberration theory is the basis for the newly proposed narcissus analysis. Two narcissus metrics are defined in terms of structural parameters of the infrared lens to be designed. The metrics provide an indirect way of controlling narcissus performance in thin lens predesign. A long wave infrared lens is discussed from a narcissus perspective within the proposed model as an example. It is shown that the proposed narcissus model is a very effective way of controlling narcissus performance, starting from the early stages of lens design.

制冷型中波红外偏振成像光学系统设计

In addition to the advantages of traditional infrared intensity imaging, such as long detection distance, all-weather working and good concealment, infrared polarization imaging technology based on the difference between the target and background polarization characteristics can effectively reduce background interference, suppress background clutter, enhance image contrast, improve signal-to-noise ratio, and has broad application prospects. In order to effectively suppress the background clutter interference in the process of air and sea detection, enhance the target detection ability in fog, haze and smoke, as well as the backgrounds of small temperature differences and low illumination, the design of a four channel aperture sharing medium-wave infrared polarization imaging optical system with a focal length of 240 mm was completed. Tolerance analysis was carried out by using Monte Carlo method to ensure the rationality of the precision of optical system processing and assembly. The results of image quality analysis show that the MTF of the optical system is close to the diffraction limit, aberrations have been effectively corrected, and the imaging quality is good. The influence of Narcissus effect on the imaging quality of the cooled infrared optical system was verified by Narcissus analysis. In addition, the optical system proposed has a compact structure and high transmittance, avoiding the use of aspheric surfaces, and has good processing and assembly technique.

Correction Method of Narcissus Effect of Cooled Infrared System Based on Differential Threshold

Correction Method of Narcissus Effect of Cooled Infrared System Based on Differential Threshold

Complacency Leading to Reduced Competitive Intensity in the Indian Information Technology Services Sector Resulting in Diminished Market Opportunity

Indian Information Technology (IT) services sector today commands a huge share of worldwide IT sourcing spend. India stays to be a driving force for worldwide sourcing growth despite rising de-globalization moves across Western economies, challenges posed by East European nations, Russia, China and East Asia. A pertinent question that comes up is how will India take on the rivalry, while the Indian IT services sector seems to be content and complacent. One can see that the hunger for growth which we saw in the late 1990s and the decade of 2000s is fast eroding. India’s incentive to the world market was its economies of scale and cost advantage; however, the disruption created by the extant outsourcing or offshoring business model is fast receding. The Indian IT Services players turned complacent while competing as disruption and differentiation gave them a unique advantage and value proposition. This article builds on various articles in this domain while analysing how complacency affects competitive intensity, in turn resulting in a reduced intensity in market growth opportunity. This article endeavours to evaluate whether Indian IT services sector is trapped in its self-projected image leading to Narcissus effect.

The ‘Narcissus Effect’: Top-down alpha-beta band modulation of face-related brain areas during self-face processing

Self-related information, such as one’s own face, is prioritized by our cognitive system. Whilst recent theoretical developments suggest that this is achieved by an interplay between bottom-up and top-down attentional mechanisms, their underlying neural dynamics are still poorly understood. Furthermore, it is still matter of discussion as to whether these attentional mechanisms are truly self-specific or instead driven by face familiarity. To address these questions, we used EEG to record the brain activity of twenty-five healthy participants whilst identifying their own face, a friend’s face and a stranger’s face. Time-frequency analysis revealed a greater sustained power decrease in the alpha and beta frequency bands for the self-face, which emerged at late latencies and was maintained even when the face was no longer present. Critically, source analysis showed that this activity was generated in key brain regions for self-face recognition, such as the fusiform gyrus. As in the Myth of Narcissus, our results indicate that one’s own face might have the potential to hijack attention. We suggest that this effect is specific to the self and driven by a top-down attentional control mechanism, which might facilitate further processing of personally relevant events.

Design and simulation of a target scene generator with a telecentric structure in the image space.

Due to the high reflectivity of the resistor array in the target scene generator (TSG), the narcissus effect caused by the resistor array is notorious. Based on the paraxial analysis of the resistor array, the telecentric structure in the image space is proposed to reduce the narcissus effect induced by the resistor array. A TSG with the telecentric structure in the image space and a TSG with the nontelecentric structure in the image space, which have same system parameters, are designed and optimized. The nonsequential ray tracing technique is used for both TSGs to evaluate the narcissus effect induced by the resistor array. The simulation results show that using a telecentric structure in the imaging space is an effective method to suppress the narcissus signal caused by the resistor array.

Automated approaches for ROIs extraction in medical thermography: a review and future directions

Historically, the skin temperature has been used as a functional indicator of the processes undergoing inside the body, where the anomalous change in temperature gives indication of illness. Infrared thermography (IRT) is a non-invasive approach which radiometrically measures the temperature distribution on the object’s surface based on emanating IR radiation. In medical field, IRT has been used to diagnose the various problems associated with superficial body parts since 1960s. The clinical abnormalities can be diagnosed by visual and subjective analysis of the thermograms, but human based diagnoses are likely to be influenced by narcissus effect, negligence, visual exhaustion and mental workload. Apart, the deep and objective diagnostic information, like severity and type of a disease can only be obtained by statistically analyse the region of interest (ROI). So, the segmentation of ROI has often been an initial step in medical diagnosis, where the automated approaches lead to fast and highly reproducible analysis. Recent advancement in deep learning opens a new way for effective computer-aided medical diagnosis, several studies have proposed deep learning based automatic segmentation and data classification. This review focuses on the wide range of image processing techniques adopted for automatic segmentation of various clinically significant ROIs, like breast, face, foot, hand etc. In addition, the present efforts are targeted on the selection of characteristic points for an effective automatic segmentation and identification of new areas to carry out the further research. Besides, the basics of medical IRT, need of automatic segmentation and factors which hinder the automatic segmentation in IRT are also discussed.

Design and fabrication of PbTe/BaF2 hydrophobic high-efficiency broad-band antireflection coating on Ge substrate in long-wave infrared region

Hydrophobic high efficiency broad-band antireflection (BBAR) coating in long-wave infrared (LWIR) region (7.5–11 µm) was designed and fabricated on germanium substrate by PVD technique. The multi-layer coating materials used in the design were Lead Telluride (PbTe) as high index material and Barium Fluoride (BaF2) as low index material. Hydrophobic high-efficiency BBAR coating with an average water contact angle of 102° was obtained only by the intrinsic surface roughness of BaF2 layer and without any surface treatment. AFM and FTIR spectrophotometer were used to investigate the surface topography and average reflection of the multi-layer coating, respectively. The average roughness obtained about 13 nm. The average reflection of the hydrophobic high-efficiency BBAR coating was 0.72% in the wavelength range from 7.5 to 11 µm that leads to eliminate Narcissus effect. Infrared optical windows and domes, having hydrophobic BBAR coatings, can effectively be applicable to humid or marine environments.

基于时空估计的冷像校正方法

基于时空估计的冷像校正方法

Influence of the Narcissus effect on the results of the calibration of test stands for measuring the parameters of optoelectronic devices

Influence of the Narcissus effect on the results of the calibration of test stands for measuring the parameters of optoelectronic devices

The tangled link between β‐ and γ‐diversity: a Narcissus effect weakens statistical inferences in null model analyses of diversity patterns

AbstractUnderstanding the structure of and spatial variability in the species composition of ecological communities is at the heart of biogeography. In particular, there has been recent controversy about possible latitudinal trends in compositional heterogeneity across localities (β‐diversity). A gradient in the size of the regional species pool alone can be expected to impose a parallel gradient on β‐diversity, but whether β‐diversity also varies independently of the size of the species pool remains unclear. A recently suggested methodological approach to correct latitudinal β‐diversity gradients for the species pool effect is based on randomization null models that remove the effects of gradients in α‐ and γ‐diversity on β‐diversity. However, the randomization process imposes constraints on the variability of α‐diversity, which in turn force γ‐ and β‐diversity to become interdependent, such that any change in one is mirrored in the other. We argue that simple null model approaches are inadequate to discern whether correlations between α‐, β‐ and γ‐diversity reflect processes of ecological interest or merely differences in the size of the species pool among localities. We demonstrate that this kind of Narcissus effect may also apply to other metrics of spatial or phylogenetic species distribution. We highlight that Narcissus effects may lead to artificially high rejection rates for the focal pattern (Type II errors) and caution that these errors have not received sufficient attention in the ecological literature.

扫描型长波红外连续变焦光学系统

Using infrared scanning system principle,a novel long-wavelength continuous zoom scanning optical system is presented based on 4 × 288 infrared MCT detector dewar cooled assembly. Related optical index parameters are resolved and calculated according to requirements of system,and the optical design parameters and outside view are obtained by the optical design software. The narcissus effect of the scanning optical system are analyzed and optimized. The optical system is composed of zoom telescope,scanning mirror,relay lens,imaging lens and a tertiary imaging system including nine lenses and two reflectors. In order to reduce cost and optical color aberrations,chalcogenide glass lens is used. The optical index is simulated,and the MTF in whole field at Nyquist frequency is over 0. 35 and distortion is below 2%. Finally the system imaging experimental verification is conducted. The results indicate that 30. 8 ~ 154 mm continuous zoom and 100% cold shield efficiency are achieved. High resolution,thermal sensibility,excellent images are validated.

THERMAL IMAGE REFINEMENT APPROACH FOR SCRATCHES ON A MAGNETIC DISK EVALUATED AT VARIOUS ANGLES

Scratch damage on magnetic disks is a major problem in the hard drive industry as it affects the reliability. To address this problem, it is therefore necessary to apply advanced detection techniques. To enhance micro-scratch detection, an infrared camera capturing technique based on heat radiation is proposed in this article. Nevertheless, the captured thermal images may be invisible due to the Narcissus effect as a dark region covering the interested areas. An approach of thermal image refinement is also presented by heating the magnetic disk at various angles of magnetic disk and CaF2 external zoom lens. The thermal image and the emissivity ratio are used to indicate suitable angles and heating times at which the scratch can be clearly detected. It is found that the rotation of the CaF2 external zoom lens can assist the detection of a micro-sized scratch and a heating time of 10 s is sufficient to clearly show scratches if the magnetic disk is set to be aligned in parallel with the CaF2 external zoom lens.

Zeno effect in degree of polarization of a single photon or quantum-state purity of a spin-1/2 system

We describe a version of the Zeno effect where the monitored physical property cannot be represented by a standard operator in the system space and the evolution to be prevented by observation is not unitary. This is the case of quantum-state purity of a spin-1/2 system, which is equivalent to the degree of polarization of a single photon. By a suitable embedding of the system (say, a single photon) in an enlarged space of a pair of photons, pure and fully mixed components lead to orthogonal subspaces, with lack of purity becoming equivalent to entanglement. By imposing desirable properties the representation of the system in the enlarged space is unique. We show that the Zeno effect is possible, and experimentally feasible, in the enlarged space. The peculiarity that photons in identical polarization states are involved in pairs to observe the dynamics of each photon allows us to refer it as the self-Zeno effect or Narcissus effect.

The research of optical windows used in aircraft sensor systems

The optical windows used in aircrafts protect their imaging sensors from environmental effects. Considering the imaging performance, flat surfaces are traditionally used in the design of optical windows. For aircrafts operating at high speeds, the optical windows should be relatively aerodynamic, but a flat optical window may introduce unacceptably high drag to the airframes. The linear scanning infrared sensors used in aircrafts with, respectively, a flat window, a spherical window and a toric window in front of the aircraft sensors are designed and compared. Simulation results show that the optical design using a toric surface has the integrated advantages of field of regard, aerodynamic drag, narcissus effect, and imaging performance, so the optical window with a toric surface is demonstrated to be suited for this application.

基于光学离焦量的致冷型长波变焦红外成像系统冷反射效应的分析与控制

基于光学离焦量的致冷型长波变焦红外成像系统冷反射效应的分析与控制

红外光学系统中衍射面冷反射的分析与评价

The narcissus influence for cooled IR imaging systems is well known and should be considered in the process of optical design. We gave a comprehensive introduction and analysis of the cause of narcissus for IR optical system and pointed the difference between diffractive surface and refractive surface for narcissus intensity evaluation. There will be multi-order diffraction after rays passing through diffractive surface. Considering the diffraction efficiency, we analyzed the narcissus influence for diffractive surface and modified the narcissus evaluation criterion YNI . A MWIR optical system with two diffractive surfaces has been given as a practical example and the narcissus effect for the two diffractive surfaces has been evaluated. The conclusion can be used to calculate and control the narcissus intensity in infrared optical systems with diffractive surfaces.

Evaluation of narcissus for multilayer diffractive optical elements in IR systems

The influence of narcissus effect for multilayer diffractive optical elements (MLDOEs) is evaluated from the viewpoint of diffraction efficiency and the narcissus intensity. A modified paraxial evaluation criterion for the reflected narcissus radiation of MLDOEs has been deduced. A practical 8-12 μm IR optical system designed with one two-layer diffractive element has been given to illustrate the distribution of incident narcissus energy among various diffraction orders in the waveband. The narcissus intensities of the two diffractive surfaces have been calculated for those diffraction orders that have the maximum diffraction efficiency. This method can be used in the process of evaluation and control of the narcissus influence in IR optical systems with MLDOEs.

Calculation and evaluation of narcissus for diffractive surfaces in infrared systems

In infrared optical systems, the narcissus effect for diffractive surfaces should be calculated with specific diffraction orders based on the diffraction efficiency. It is shown in this work that the diffraction order of maximum diffraction efficiency varies with the change of the incident angle and wavelength of the backward-traced narcissus flux. Meanwhile, yni, which is the paraxial evaluation criterion of narcissus intensity for a refractive surface, is modified considering diffraction when a ray passes through diffractive surfaces, and a practical example has been given. The analysis can be used to calculate and control the narcissus intensity in infrared optical systems with diffractive surfaces.

Study on the Use of Motion Compensation Techniques to Determine Heat Sources. Application to Large Deformations on Cracked Rubber Specimens

This paper deals with the determination of the thermal response of elastomeric materials subjected to cyclic loading. In this case, the material undergoes large deformations, so a suitable motion compensation technique has been developed to track the material points and their temperature during the test. Special attention is paid to the Narcissus effect and to the detector matrix of the infrared camera used in the study. Heat sources are then derived from the temperature maps. The thermoelastic inversion phenomenon has been experimentally evidenced during a cyclic test performed on an elastomeric notched specimen. The heat source distribution close to the crack tip has also been deduced from the temperature maps, thus highlighting the relevance of the approach.