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.

Design of Athermalized Infrared Telephoto Lens

2013 ◽  
Vol 552 ◽  
pp. 8-13
Author(s):  
Yu Zhang ◽  
Ji Yang Shang ◽  
Yue Xu ◽  
Wen Sheng Wang
Keyword(s):  
Image Quality ◽  
Optical System ◽  
Power Distribution ◽  
Focal Length ◽  
Diffraction Limit ◽  
Field Of View ◽  
Optical Systems ◽  
Modulation Transfer ◽  
Full Field ◽  
Telephoto Lens

IR optical system is much more appropriate to be applied in cluttered and formidable conditions. The change of temperature could degrade image quality of the infrared optical system. So the athermalization becomes the difficult part and key factor in the designing of MWIR optical systems for working under temperature range of -40°C~60°C. In this paper, the infrared telephoto lens is designed; it meets the designing requirements and has good image quality. The effective focal length is 240mm and the F-number is 2.The full field of view is 3.2°. In order to balance the chromatic aberration, an aspherical surface is used in the athermalized infrared optical system. Through carefully selected optical material and reasonable optical power distribution, passive optical athermalization can be realized. The curve of MTF is close to diffraction limit. Within the working temperature, the value of MTF at 30cy/mm is always large than 0.6. The results show that the modulation transfer function (MTF) of optical system in all field of view approaches the diffraction limit at different temperature, and 80% energy concentrates in 1 pixel.

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.

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.

Structural Parameters Optimum Design of the New Type of Optical Aiming System

2014 ◽  
Vol 8 (1) ◽  
pp. 208-212
Author(s):  
Deng Xiang ◽  
Liu Kai ◽  
Wang Jidong
Keyword(s):  
Optimum Design ◽  
Working Conditions ◽  
Optical System ◽  
Modulation Transfer Function ◽  
Structural Parameters ◽  
Focal Length ◽  
Angle Measurement ◽  
Measurement Technology ◽  
Modulation Transfer ◽  
New Type

Combination of gyro north-finder, self-collimation photoelectric theodolite can be composed a ground rapid directional aiming system. In the paper, based on the CCD angle measurement technology, the self-collimation optical system is redesigned, focal length of the optical system is calculated, and the appropriate parameters are chosen. Optical conjugate design of the three light paths of light source module, visual module, and CCD receiving module is adopted to synchronize the transmission beams of the three light paths. The simulation and optimum design of light paths in the optical system are achieved by using the ZEMAX software. By analyzing the spot diagram and modulation transfer function (MTF), appropriate structural parameters of the optical system suitable for aiming working conditions are obtained.

Athermalization of Long Focal Length IR Optical Systems by Hydraulics

2013 ◽  
Vol 552 ◽  
pp. 38-43
Author(s):  
Jun Yan Zhao ◽  
Guang Hu Du ◽  
Zhi Peng Qin
Keyword(s):  
Optical System ◽  
Thermal Effects ◽  
Focal Length ◽  
Optical Systems ◽  
Depth Of Focus ◽  
Temperature Changes ◽  
Temperature Range ◽  
Effects Of Temperature

The effects of temperature changes on the focus of IR optical system are described in this paper, and the general methods used for compensation of thermal effects are analyzed. On this basis, the feasibility of athermalization of long focal length IR optical systems by using of hydraulics is studied, and an athermalization design of an uncooled IR optical system with focal length 200mm and F-number 1 is presented. The result shows that within the temperature range from -30 to 50 °C, the defocus of this system is less than the depth of focus.

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.

CALCULATION OF MODULATION TRANSFER FUNCTION OF AN OPTICAL SYSTEM BY USING SKEW RAY TRACING

2009 ◽  
Vol 33 (3) ◽  
pp. 429-442 ◽  
Author(s):  
Kuo-Hwa Tseng ◽  
Chieh Kung ◽  
Te-Tan Liao ◽  
Hao-Peng Chang
Keyword(s):  
Transfer Function ◽  
Ray Tracing ◽  
Optical System ◽  
Modulation Transfer Function ◽  
Image Plane ◽  
Modulation Transfer ◽  
Light Rays ◽  
Intermediate Image ◽  
Pass Through ◽  
And Performance

The resolution and performance of an optical system can be characterized by a quantity known as the modulation transfer function (MTF), which is a measurement of an optical system’s ability to transfer contrast from the specimen to the intermediate image plane at a specific resolution. Accordingly, this study employs skew ray tracing based on a 4 × 4 homogeneous coordinate transformation matrix and Snell’s law to develop a detailed methodology for determining the spot diagram on the image plane when light rays pass through the optical system. And the authors present calculations of the MTF of an optical system by using the spot diagram on the image plane. The numerical results of the proposed methodology are demonstrated using a symmetrical optical system.

The Small Telescopes Performance in the Visual to Near Infrared Wavelengths

2015 ◽  
Vol 771 ◽  
pp. 129-132
Author(s):  
Dhani Herdiwijaya
Keyword(s):  
Optical System ◽  
Near Infrared ◽  
Focal Length ◽  
Low Cost ◽  
Sloan Digital Sky Survey ◽  
Modulation Transfer ◽  
Sky Survey ◽  
Infra Red ◽  
Infrared Wavelengths ◽  
Bar Test

Optical system is important and optimized for highly spatial resolution in certain wavelength bandwidth. We tested three small refractor telescopes with different aperture (two telescopes with 80 mm in diameter and one with 66 mm diameter) and focal-length (544 mm, 400 mm, and 389 mm, respectively) in order to know the resolution from visual to near infra red regions. The images of sinusoidal bar test chart were recorded from CCD detector. The reference filter of Sloan Digital Sky Survey (SDSS) is also attached in front of detector. The filters have the range of G (401-550 nm), R (555-695 nm), I (690-820 nm), Z (>820 nm), Z_s (826-920 nm), and Y (950-1058 nm). The last filter is referred to the limit of quantum efficiency of the detector. The maximum frequency for each pixel from each Modulation Transfer Function (MTF) was performed. We found that smaller diameter telescope is better resolution in the visual wavelength than the wider diameter and longer focal-length. In the near infra red region, the opposite results were obtained. The coating lens quality may affect the wavelength dependences. This study has advantages of selecting low cost and high resolution optical system for different applications, e.g. very young crescent moon observation, etc.

scholarly journals A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical Systems

2020 ◽  
Vol 10 (20) ◽  
pp. 7087
Author(s):  
Jinwon Jung ◽  
Nguyen Van Sy ◽  
Dongkyu Lee ◽  
Seonggun Joe ◽  
Jaihyuk Hwang ◽  
...  
Keyword(s):  
High Resolution ◽  
Optical System ◽  
High Vacuum ◽  
Longitudinal Direction ◽  
Image Resolution ◽  
Optical Systems ◽  
Modulation Transfer ◽  
Small Satellites ◽  
Single Motor ◽  
Flexure Hinges

For earth observation, the optical systems in small satellites are crucial to obtain high- resolution images. However, the alignment between a primary and a secondary mirror in an optical system can be disturbed due to the harsh environments inside vehicles or space (i.e., vibrations, shock loading during launch, dramatic temperature changes, or high vacuum pressure in space). To compensate for such undesired deformations, a focusing mechanism should be embedded into the optical system. In this paper, we propose a novel Single Motor-Driven Focusing mechanism with Flexure Hinges (SMFH), allowing the Flexure Hinge (FlexHe) to displace in the longitudinal direction. The presented FlexHe incorporates radial zig-zag-patterned slits to achieve flexibility, and preloading of the hinge structures to reduce the resulting hysteresis. To investigate an optimal configuration of FlexHe, a numerical simulation is performed by means of ANSYS 19.2. The variation of Modulation Transfer Function (MTF), corresponding to an image resolution, is evaluated by using an optics simulation program (CODE-V). The experimental setups are built by exploiting the fabricated SMFH and five LVDT (Linear Variable Differential Transformer) sensors with a high resolution of 0.031 µm. As a result, hysteresis can be reduced up to 6.52% with a pre-stretched length of 3 µm. The proposed SMFH allows not only the De-space to displace up to 23.93 µm, but also the De-center and the Tilt to achieve the desired displacements of 5.20 µm and 88.45 µrad, respectively. Conclusively, the SMFH shows promising characteristics to embed a feedback control, due to its high resolution (up to 0.1 µm) for De-space with the MTF of 37%.

scholarly journals Optical System for the Transit Spectral Observation of Exoplanet-Atmosphere Characteristics

2021 ◽  
Vol 11 (12) ◽  
pp. 5508
Author(s):  
Fang Wang ◽  
Xuewu Fan ◽  
Hu Wang ◽  
Yue Pan ◽  
Yang Shen ◽  
...  
Keyword(s):  
Optical System ◽  
Signal To Noise Ratio ◽  
Optical Systems ◽  
Optical Parameters ◽  
Optical Index ◽  
Dual Channel ◽  
Performance Requirements ◽  
Reliable Performance ◽  
Parameter Ranges

Optical instrumentation with reliable performance is essential for the research of exoplanet atmosphere characteristics. However, due to long distances and weak signals, exoplanets are difficult to be imaged by traditional optical systems. To this end, a novel optical system based on transit spectroscopy is proposed in this paper. On the basis of the principle of the transit-spectroscopy method and the astronomical parameters of observed targets, the optional parameter ranges of a dedicated optical system are analyzed. The transit signal-to-noise ratio (SNR) is introduced for the determination of telescope aperture and throughput. Furthermore, an example of the optical system with a space telescope and spectrometer is proposed according to the above optical index, which is proven to meet the performance requirements. The optical system is required to cover the wavelength of 0.5–8 m and the field of view (FOV) of 27.9′′ within the diffraction limit. The collecting aperture should be greater than 2 m, and spectral resolutions of two spectrometer channels should approximately be 100 (2–4 m) and 30 (4–8 m). The point-spread function (PSF) of each channel at the minimal wavelength should cover 2 pixels. The telescope and dichroic system provide diffraction-limited input beams with the required aperture, FOV, and wavelength for the spectrometer slits. The simulation results of the optical system show that the spectral resolutions of the dual-channel spectrometer were 111–200 and 43–94. The image points of the spectrometer in each wavelength were smaller than the Airy spot within the slit FOV, and the full width at half-maximum (FWHM) of PSF at λmin provided 2 pixels of 18 m sampling. The feasibility of the demonstrated optical parameters is proven by the design.

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