The quality of X-ray optics on beamline is a key factor that limits the performance of the beam line to play. For X-ray mirror surface characterization with high accuracy, long trace profiler and NOM for flat or sligh...
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ISBN:
(纸本)9781628419221
The quality of X-ray optics on beamline is a key factor that limits the performance of the beam line to play. For X-ray mirror surface characterization with high accuracy, long trace profiler and NOM for flat or slight curved mirror have been developed. However, these two kind of instruments cannot measure the highly curved mirror since requirement of high precision and that of large range contradict each other. In this paper, we proposed a novel wavefront-coding-based surface slope metrology technique. Four-dimension information of the optics under test, including x-y position and sagittal/tangential angle, is provided. Due to the focused beam used and the high speed DMD (Digital Mirror Device), high spatial resolution of the measurement is obtained. In experiment, we demonstrated this technique by measuring bend-based high energy monochromator developed in BSRF.
Because of obvious drawbacks including serious artefacts and noise in a decoded image, the existing wavefront coding infrared imaging systems are seriously restricted in application. The proposed ultra-precision diamo...
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Because of obvious drawbacks including serious artefacts and noise in a decoded image, the existing wavefront coding infrared imaging systems are seriously restricted in application. The proposed ultra-precision diamond machining technique manufactures an optical phase mask with a form manufacturing errors of approximately 770 nm and a surface roughness value Ra of 5.44 nm. The proposed decoding method outperforms the classical Wiener filtering method in three indices of mean square errors, mean structural similarity index and noise equivalent temperature difference. Based on the results mentioned above and a basic principle of wavefront coding technique, this paper further develops a wavefront coding infrared imaging system. Experimental results prove that our wavefront coding infrared imaging system yields a decoded image with good quality over a temperature range from -40 degrees C to + 70 degrees C.
We have implemented an extended depth of field optical system by wavefront coding with a micromachined membrane deformable mirror. This approach provides a versatile extension to standard wavefront coding based on fix...
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ISBN:
(纸本)9781628414257
We have implemented an extended depth of field optical system by wavefront coding with a micromachined membrane deformable mirror. This approach provides a versatile extension to standard wavefront coding based on fixed phase mask. First experimental results validate the feasibility of the use of adaptive optics for variable depth wavefront coding in imaging optical systems.
wavefront coding is a technology which combination of the optical design and digital image *** inserting a phase mask closed to the pupil plane of the optical system,the wavefront of the system is *** the depth of foc...
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wavefront coding is a technology which combination of the optical design and digital image *** inserting a phase mask closed to the pupil plane of the optical system,the wavefront of the system is *** the depth of focus is extended *** reality the idea is same as the athermalization theory of infrared optical *** this paper,an uncooled infrared dual field optical system with effective focal as 38mm/19 mm,F number as 1.2 of both focal length,operating wavelength varying from 8μm to 12μm was designed.A cubic phase mask was used at the pupil plane to re-modulate the *** the performance of the infrared system was simulated with CODEV as the environment temperature varying from-40 D to 60 *** curve of the optical system with phase mask are compared with the outcome before using phase *** result show that wavefront coding technology can make the system not sensitive to thermal defocus,and then realize the athermal design of the infrared optical system.
wavefront coding technique has been used widely to extend the depth of field of optical systems since it was proposed by Dowski and Cathey in ***,it belongs to computational imaging which
ISBN:
(纸本)9781510607682
wavefront coding technique has been used widely to extend the depth of field of optical systems since it was proposed by Dowski and Cathey in ***,it belongs to computational imaging which
A wavefront coding (WFC) technique provides an extension of the depth of field for a microscopy imaging system with slight loss of image spatial resolution. Through the analysis of the relationship between the inciden...
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A wavefront coding (WFC) technique provides an extension of the depth of field for a microscopy imaging system with slight loss of image spatial resolution. Through the analysis of the relationship between the incidence angle of light at the phase mask and the system pupil function, a mixing symmetrical cubic phase mask (CPM) applied to 5X-40X micro-objectives is optimized simultaneously based on point-spread function (PSF) invariance and nonzero mean values of the modulation transfer function (MTF) near the spatial cut-off frequency. Optimization results of the CPM show that the depth of field of these micro-objectives is extended 3-10 times respectively while keeping their resolution. Further imaging simulations also prove its ability in enhancing the defocus imaging.
Optical transfer functions (OTFs) on various directional spatial frequency axes for cubic phase mask (CPM) with circular and square apertures are investigated. Although OTF has no zero points, it has a very close valu...
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Optical transfer functions (OTFs) on various directional spatial frequency axes for cubic phase mask (CPM) with circular and square apertures are investigated. Although OTF has no zero points, it has a very close value to zero for a circular aperture at low frequencies on diagonal axis, which results in degradation of restored images. The reason for close-to-zero value in OTF is also analyzed in connection with point spread function profiles using Fourier slice theorem. To avoid close-to-zero condition, square aperture with CPM is indispensable in WFC. We optimized cubic coefficient a of CPM and coefficients of digital filter, and succeeded to get excellent de-blurred images at large depth of field.
Artefacts and noise degrade the decoded image of a wavefront coding infrared imaging system, which usually results in the decoded image being inferior to the in-focus infrared image of a conventional infrared imaging ...
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ISBN:
(纸本)9781510601680
Artefacts and noise degrade the decoded image of a wavefront coding infrared imaging system, which usually results in the decoded image being inferior to the in-focus infrared image of a conventional infrared imaging system. The previous letter showed that the decoded image fell behind the in-focus infrared image. For comparison, a bar target experiment at temperature of +20 degrees C and two groups of outdoor experiments at temperatures of +28 degrees C and +70 degrees C are respectively conducted. Experimental results prove that a wavefront coding infrared imaging system can achieve the decoded image being approximating to its corresponding in-focus infrared image.
wavefront coding, a technique of optical-digital hybrid image, can be used to extend the depth of the field. However, it sacrifices the signal-to-noise ratio (SNR) of system at a certain degree, especially on focus si...
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ISBN:
(纸本)9781628417647
wavefront coding, a technique of optical-digital hybrid image, can be used to extend the depth of the field. However, it sacrifices the signal-to-noise ratio (SNR) of system at a certain degree, especially on focus situation. The on-focus modulation transfer function (MTF) of wavefront coding system is much lower than that of generally traditional optical system. And the noise will be amplified in the digital image processing. This paper analyzes characteristics of the SNR of the wavefront coding system in the frequency domain and calculates the rate of noise amplification in the digital processing. It also explains the influence of the image detector noise severely reducing the restored quality of images. In order to reduce noise amplification in the process of image restoration, we propose a modified wiener filter which is more suitable for restoration in consideration of noise suppression. The simulation experiment demonstrates that the modified wiener filter, compared with traditional wiener filter, has much better performance for wavefront coding system and the restored images having much higher SNR in the whole depth of the field.
In this paper, we introduce the novel method to improve the image quality for the optical imaging system with the radially symmetrical phase masks. By introducing 0-pi phase mask into the radially symmetrical one, the...
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In this paper, we introduce the novel method to improve the image quality for the optical imaging system with the radially symmetrical phase masks. By introducing 0-pi phase mask into the radially symmetrical one, the new phase mask is generated, which produces the dark-shape point spread function. By rotating this phase mask with the amplitude mask for different angles, the point spread function is still rotated by the same angle. Moreover, the digital processing is used to restore the high-quality image. The simulation results demonstrated the effectiveness of the proposed method in comparison to the previously radially symmetrical phase mask.
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