A Precise MTF Measurement Method of Programmable Optical Systems

2013 ◽  
Vol 552 ◽  
pp. 497-501
Author(s):  
Yu Long Song
Keyword(s):  
Optical System ◽  
Measurement Method ◽  
Image Sensor ◽  
Time Sequence ◽  
Measurement Methods ◽  
Test Equipment ◽  
Optical Systems ◽  
Coded Aperture ◽  
Program Logic ◽  
And Performance

The programmable coded aperture has been applied to the optical systems to enhance their functionality and performance. Therefore, the optical system is programmable. It means that the optical system could be changed momentarily. Conventionally, during MTF measurement, the optical system is fixed. The system under test and the test equipment have no relation of time- sequence. The image sensor sample of test equipment can be random. But In the programmable optical system, the aperture style and its duration in a frame period have a impact on the system MTF. Conventional MTF measurement methods can’t be used to test accurately the MTF of programmable optical system. In this paper, we propose a method and design a system which can test precisely MTF of the programmable optical system. In this method the sample of a sensor would be synchronized with the coded aperture program logic, which ensures the precision of MTF measurement.

Comparison of Design and Spatial Stability of Two Kinds of Optical Systems for Stereoscopic Mapping Camera

2013 ◽  
Vol 760-762 ◽  
pp. 368-372
Author(s):  
Tian Jin Tang ◽  
Wei Jun Gao
Keyword(s):  
Optical System ◽  
Linear Array ◽  
Focal Length ◽  
Optical Systems ◽  
Modulation Transfer ◽  
Working Temperature ◽  
Edge Field ◽  
Performance Requirements ◽  
And Performance ◽  
Structure Layout

To achieve a certain precision when mapping in accord with a particular proportion or scale with stereo mapping camera, the change of chief ray height of the edge field due to the fluctuation of working temperature is required to be within the range of microns, and at the meantime the size and structure layout of three-linear array stereo mapping camera are determined directly by the configuration of optical system. Based on the requirements of refractive optical system with long focal length, academic calculation and actual optical designs based on two typical configurations for stereoscopic mapping camera are made,the actual working temperature and performance requirements are also taken into consideration, the results including the modulation transfer function, distortion and stability comparison are also given.

MODELING AND PERFORMANCE EVALUATION OF OPTICAL SYSTEMS USING SKEW RAY TRACING

2007 ◽  
Vol 31 (2) ◽  
pp. 143-156
Author(s):  
Te-Tan Liao ◽  
Jing-Fung Lin
Keyword(s):  
Ray Tracing ◽  
Optical System ◽  
Monochromatic Light ◽  
Merit Function ◽  
Optical Systems ◽  
Optical Aberrations ◽  
Algebra Approach ◽  
Homogeneous Transformation Matrix ◽  
Overall Performance ◽  
And Performance

This paper applies a computational geometric algebra approach based on a 4 x 4 homogeneous transformation matrix to model optical systems and to evaluate their performance. In the proposed approach, the directions of the refracted/reflected rays at each boundary in the optical system are determined using skew ray tracing based upon Snell’s law. The differential changes in the image coordinates caused by optical aberrations are derived for both polychromatic and monochromatic light by applying a sensitivity analysis approach. Finally, a merit function is constructed comprising five individual defect items in order to evaluate the overall performance of a generic optical system. The proposed analytical approach provides a comprehensive and robust approach for the modeling and evaluation of optical systems.

scholarly journals A Novel Focal Length Measurement Method for Center-Obstructed Omni-Directional Reflective Optical Systems

2019 ◽  
Vol 9 (11) ◽  
pp. 2350 ◽  
Author(s):  
Hojong Choi ◽  
Joo-Youn Jo ◽  
Jae-Myung Ryu
Keyword(s):  
Optical System ◽  
Measurement Method ◽  
Focal Length ◽  
Tolerance Analysis ◽  
Field Of View ◽  
Optical Systems ◽  
Wide Field ◽  
Surveillance Camera ◽  
Length Measurements ◽  
Design Software

An omni-directional optical system can be used as a surveillance camera owing to its wide field angle. In cases in which a system is designed with a central screen obscuring structure to increase the resolution of the off-axis field, however, the conventional methods cannot be used to measure the effective focal length (EFL). We assumed the actual and theoretical distortion values of the fabricated optical system to be the same and determined the system’s EFL by finding the minimum deviation point of the measured and theoretical distortions. The feasibility of the determined EFL was verified through a tolerance analysis of the system. For these precise measurements we also analyzed the sources of error. To verify our proposed measurement method, we measured the focal length of a center-obstructed omni-directional reflective optical system with an 80–135° field of view (FOV). The EFL from the measurement was 0.3739 mm and was only approximately 11 µm different from the EFL calculated using the design software. Thus, the reliability of focal length measurements in omni-directional optical systems was improved.

Atomic Resolution in Crystal Aperture Stem

1990 ◽  
Vol 48 (1) ◽  
pp. 236-237
Author(s):  
J T Fourie
Keyword(s):  
Optical System ◽  
Spherical Aberration ◽  
Three Dimensional ◽  
Transmission Function ◽  
Optical Systems ◽  
Bragg Angle ◽  
Electron Optical System ◽  
Intimate Contact ◽  
Diffraction Effects ◽  
Design Aspect

The attempts at improvement of electron optical systems to date, have largely been directed towards the design aspect of magnetic lenses and towards the establishment of ideal lens combinations. In the present work the emphasis has been placed on the utilization of a unique three-dimensional crystal objective aperture within a standard electron optical system with the aim to reduce the spherical aberration without introducing diffraction effects. A brief summary of this work together with a description of results obtained recently, will be given.The concept of utilizing a crystal as aperture in an electron optical system was introduced by Fourie who employed a {111} crystal foil as a collector aperture, by mounting the sample directly on top of the foil and in intimate contact with the foil. In the present work the sample was mounted on the bottom of the foil so that the crystal would function as an objective or probe forming aperture. The transmission function of such a crystal aperture depends on the thickness, t, and the orientation of the foil. The expression for calculating the transmission function was derived by Hashimoto, Howie and Whelan on the basis of the electron equivalent of the Borrmann anomalous absorption effect in crystals. In Fig. 1 the functions for a g220 diffraction vector and t = 0.53 and 1.0 μm are shown. Here n= Θ‒ΘB, where Θ is the angle between the incident ray and the (hkl) planes, and ΘB is the Bragg angle.

Assessing bias, precision, and agreement in method comparison studies

2019 ◽  
Vol 29 (3) ◽  
pp. 778-796 ◽  
Author(s):  
Patrick Taffé
Keyword(s):  
Measurement Method ◽  
Method Comparison ◽  
Estimation Procedure ◽  
Measurement Methods ◽  
Repeated Measurements ◽  
Confidence Bands ◽  
The Other ◽  
Reference Standard ◽  
Simultaneous Confidence Bands ◽  
Index Of Agreement

Recently, a new estimation procedure has been developed to assess bias and precision of a new measurement method, relative to a reference standard. However, the author did not develop confidence bands around the bias and standard deviation curves. Therefore, the goal in this paper is to extend this methodology in several important directions. First, by developing simultaneous confidence bands for the various parameters estimated to allow formal comparisons between different measurement methods. Second, by proposing a new index of agreement. Third, by providing a series of new graphs to help the investigator to assess bias, precision, and agreement between the two measurement methods. The methodology requires repeated measurements on each individual for at least one of the two measurement methods. It works very well to estimate the differential and proportional biases, even with as few as two to three measurements by one of the two methods and only one by the other. The repeated measurements need not come from the reference standard but from either measurement methods. This is a great advantage as it may sometimes be more feasible to gather repeated measurements with the new measurement method.

Research on Online Measurement Method of Hole Diameter and Position

2013 ◽  
Vol 347-350 ◽  
pp. 197-200
Author(s):  
Yu Gong ◽  
Jing Cai Zhang ◽  
Hong Qi Liu
Keyword(s):  
Comparative Analysis ◽  
Measurement System ◽  
Measurement Method ◽  
Measurement Methods ◽  
Hole Diameter ◽  
Laser Sensor ◽  
Online Measurement ◽  
Online Detection ◽  
Ccd Imaging ◽  
Inductive Sensor

In this paper, research on measurement methods of hole during the parts online detection has been made. Both diameter and position of the hole are going to be detected in the same measurement system. In order to obtain higher accuracy and efficiency, a comparative analysis test of using the contact probes, the inductive sensor, the laser sensor, the forward and back lighting CCD imaging have been achieved. Results show that the contact measurement using inductive sensor is more suitable for the system, for the reason that it has higher reliability and efficiency.

Cross Calibration by FFT Equalization

1997 ◽  
Vol 119 (2) ◽  
pp. 236-242 ◽  
Author(s):  
K. Peleg
Keyword(s):  
Measurement Method ◽  
Functional Relationship ◽  
Measurement Methods ◽  
New Method ◽  
Measurement Systems ◽  
True Value ◽  
Calibration Problem ◽  
Regression Techniques ◽  
The Cross ◽  
Cross Calibration

The classical calibration problem is primarily concerned with comparing an approximate measurement method with a very precise one. Frequently, both measurement methods are very noisy, so we cannot regard either method as giving the true value of the quantity being measured. Sometimes, it is desired to replace a destructive or slow measurement method, by a noninvasive, faster or less expensive one. The simplest solution is to cross calibrate one measurement method in terms of the other. The common practice is to use regression models, as cross calibration formulas. However, such models do not attempt to discriminate between the clutter and the true functional relationship between the cross calibrated measurement methods. A new approach is proposed, based on minimizing the sum of squares of the differences between the absolute values of the Fast Fourier Transform (FFT) series, derived from the readings of the cross calibrated measurement methods. The line taken is illustrated by cross calibration examples of simulated linear and nonlinear measurement systems, with various levels of additive noise, wherein the new method is compared to the classical regression techniques. It is shown, that the new method can discover better the true functional relationship between two measurement systems, which is occluded by the noise.

A novel velocity measurement method based on contact image sensor

2021 ◽  
Author(s):  
Xiaoxian Lian ◽  
Yichao Zhu ◽  
Lijing Zhang ◽  
Lianyou Lai ◽  
weijian xu
Keyword(s):  
Velocity Measurement ◽  
Measurement Method ◽  
Image Sensor

scholarly journals Comparison of three measurement methods of saturated hydraulic condutivity

2006 ◽  
Vol 3 (3) ◽  
pp. 987-1019 ◽  
Author(s):  
C. Fallico ◽  
E. Migliari ◽  
S. Troisi
Keyword(s):  
Hydraulic Conductivity ◽  
Measurement Method ◽  
Sandy Loam ◽  
Measurement Methods ◽  
Soil Core ◽  
Statistical Parameters ◽  
Factors Affecting ◽  
Average Value ◽  
Constant Head ◽  
Log Normal

Abstract. After pointing out the importance of the saturated hydraulic conductivity (ks) measurements and the difficulties and uncertainties that are present, and after recalling salient aspects of three well-known measurement methods of this parameter (i.e. constant-head tension infiltrometer (TI) method, constant-head pressure infiltrometer (PI) method and soil core (SC) estimates method), the results of an investigation on data which were obtained during a measurement campaign on an area of 800 m2, on a sandy loam hillslope, located in Southern Italy, were carried out again here. Three sets of values of ks, obtained with these measurement methods, were analyzed statistically, verifying that the log-normal distribution describes these better than the normal one; moreover, the more significant statistical parameters of each set were compared (average value , amplitude A, coefficient of variation CV and standard deviation SD), individualizing the more significant differences. The greatest value of hydraulic conductivity was found with method (PI), while the smallest with (SC) and the intermediate with (TI); these differences were translated into macroporosity and into the influence of the single measurement method. Moreover, referring to the possible factors affecting the results, the importance can be noted of the structure, the texture and the soil events, in terms of utilization, which can affect the measure of ks leading often to very different values even for similar soils, but with a different history, independently of the coincidence of the measurement points and they can be determining to explain the differences affecting the results obtained in analogous investigations by other researchers. Having confirmed that generalization is not possible, the need was emphasized to adopt the necessary devices relating to the specific measurement method, case by case, and to carefully explain the obtained results, in the light of the peculiarities and the limits of each situation. Finally, the results of similar statistical analysis carried out on a greater number of ks values, measured through the (TI) and (PI) methods are shown in this paper, with some statistical considerations on the increasing of the measurements number.

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