Surface measurement with Shack-Hartmann wavefront sensing technology

Li, X.; Zhao, Liping; Fang, Zhijie; Asundi, Anand; Yin, Xiaoming

doi:10.1117/12.814541

Cited by 7 publications

(6 citation statements)

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“…The initial usage of the Shack-Hartmann Wavefront Sensor (SHWS) is in astronomical imaging. The application of this sensor in metrology, ophthalmic imaging and other research areas has been widely explored [1,24,25] since it is made available in the market due to the advancement of technology. Specifically, it is used to measure aberrations on the corneal surface [26] and the lens of the eye.…”

Section: The Gated Shack-hartmann (Gsh) Wavefront Sensing In Multi-lamentioning

confidence: 99%

“…For simplicity, as shown in Figure 1, only the Shack-Hartmann lenslet array, gated camera and collimating lenses are involved in the measurement. The system is based on the design from recent researches [5,24] but it is coupled with a gated camera/sensor [35] to measure the time necessary for the light to propagate within the interfaces. It is assumed to be (but not limited) non-interferometric wavefront sensing approach, that only discrete reflection or diffraction was observed at the interface.…”

Section: The Gated Shack-hartmann (Gsh) Wavefront Sensing In Multi-lamentioning

confidence: 99%

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Method for distortion correction of multi-layered surface reconstruction using time-gated wavefront sensing approach

Tan

Wang

Han³

et al. 2013

J. Eur. Opt. Soc.-Rapid Publ.

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In order to estimate the multi-layer surface profile and to detect the inter-layer surfaces defects, gated wavefront sensing approach has been proposed in the previous works [1,2]. However, the proposed methodology measures the wavefront that has been distorted by its prior surfaces (reflected wavefront) or post surfaces (transmitted wavefront). Analysis has to be performed to estimate the multi-layer wavefront sensing by taking into consideration the multi-layer surfaces condition. For reflected wavefront, the bottom layer(s) wavefront is (are) being distorted twice via separate interface points while traveling back to the lenslet arrays through our observation for the slope and phase measurement. The subsequent reconstructed surfaces are not accurate and corrected. Thus, a discrete layer correction technique for the surface reconstruction has been proposed to enhance the reconstruction accuracy by using the upper/top layer's wavefront information. This paper discusses on the case of 2-layer system, where the reflected wavefront from the bottom layer has been distorted and its surface reconstruction has been corrected. The results show that the distortion is significant and the correction is deemed necessary for industrial application such as in wafer warpage inter-layer profile estimation.

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Section: The Gated Shack-hartmann (Gsh) Wavefront Sensing In Multi-lamentioning

confidence: 99%

Section: The Gated Shack-hartmann (Gsh) Wavefront Sensing In Multi-lamentioning

confidence: 99%

Method for distortion correction of multi-layered surface reconstruction using time-gated wavefront sensing approach

Tan

Wang

Han³

et al. 2013

J. Eur. Opt. Soc.-Rapid Publ.

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“…The output wavefront approximates two times the surface profile. A more detailed description of the wavefront simulation can be found in [11].…”

Section: Optical System For Surface Measurementmentioning

confidence: 99%

“…A commonly used tool to measure the surface profile is a stylus instrument [3]. However, a non-contact measurement instrument is preferred to a contact instrument for most surface [11]). measurement applications.…”

Section: Introductionmentioning

confidence: 99%

Automatic centroid detection and surface measurement with a digital Shack–Hartmann wavefront sensor

Yin¹,

Zhao²,

Li³

et al. 2009

Meas. Sci. Technol.

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With the breakthrough of manufacturing technologies, the measurement of surface profiles is becoming a big issue. A Shack-Hartmann wavefront sensor (SHWS) provides a promising technology for non-contact surface measurement with a number of advantages over interferometry. The SHWS splits the incident wavefront into many subsections and transfers the distorted wavefront detection into the centroid measurement. So the accuracy of the centroid measurement determines the accuracy of the SHWS. In this paper, we have presented a new centroid measurement algorithm based on an adaptive thresholding and dynamic windowing method by utilizing image-processing techniques. Based on this centroid detection method, we have developed a digital SHWS system which can automatically detect centroids of focal spots, reconstruct the wavefront and measure the 3D profile of the surface. The system has been tested with various simulated and real surfaces such as flat surfaces, spherical and aspherical surfaces as well as deformable surfaces. The experimental results demonstrate that the system has good accuracy, repeatability and immunity to optical misalignment. The system is also suitable for on-line applications of surface measurement.

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“…The device that measures the aberrations in the wavefront is termed as wavefront sensor, and the technique of measuring the unknown phase profile o r t he e stimation o f t he w avefront i s k nown a s w avefront s ensing. For the past few decades, wavefront sensors have played a significant r ole i n d iverse a reas s uch a s: i n a stronomy to build adaptive optics for astronomical telescopes, 1 in ophthalmology for perfect correction of human vision, [2][3][4] in the semiconductor industry for analysis of flatness o f t he surface, 5,6 a nd i n s urface a nd t hickness profile measurement. [7][8][9] It has also been used in free-space optical communication to transmit and receive the data accurately.…”

Section: Introductionmentioning

confidence: 99%

Improvement in wavefront measurement accuracy in grating array-based zonal wavefront sensors by modulating the intensity profile of the incident beam

Kumar¹,

Choudhury²,

Sherpa³

et al. 2023

Practical Holography XXXVII: Displays, Materials, and Applications

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The wavefront measurement accuracy of a grating array based zonal wavefront sensor (GAWS) can be affected by the non-uniform focal spot array and unwanted orders in the detector plane. The non-uniform focal spot array is the outcome of the non-uniform nature of the incident illumination beam’s intensity profile. This paper describes a method that dynamically modulates the laser beam’s intensity using computer generated holography, making the focal spot array uniform and eliminating unwanted spots in a detector plane, thereby enhancing the accuracy of the wavefront measurement. Here, we present proof-of-principle simulation results that demonstrate the working of the proposed improvements in GAWS.

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Surface measurement with Shack-Hartmann wavefront sensing technology

Cited by 7 publications

References 0 publications

Method for distortion correction of multi-layered surface reconstruction using time-gated wavefront sensing approach

Method for distortion correction of multi-layered surface reconstruction using time-gated wavefront sensing approach

Automatic centroid detection and surface measurement with a digital Shack–Hartmann wavefront sensor

Improvement in wavefront measurement accuracy in grating array-based zonal wavefront sensors by modulating the intensity profile of the incident beam

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