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Yeddanapudi Pavan Kumar

Bio: Yeddanapudi Pavan Kumar is an academic researcher from Raja Ramanna Centre for Advanced Technology. The author has contributed to research in topics: Geometrical optics & Curvature. The author has an hindex of 1, co-authored 1 publications receiving 29 citations.

Papers
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Journal ArticleDOI
TL;DR: This work presents what it believes is a new technique for the focal-length measurement of positive lenses using Fizeau interferometery, which utilizes the Gaussian lens equation.
Abstract: We present what we believe is a new technique for the focal-length measurement of positive lenses using Fizeau interferometery. The technique utilizes the Gaussian lens equation. The image distance is measured interferometrically in terms of the radius of curvature of the image-forming wavefront emerging from the lens. The radii of curvature of the image-forming wavefronts corresponding to two different axial object positions of known separation are measured. The focal length of the lens is determined by solving the equations obtained using the Gaussian lens equation for the two object positions. Results obtained for a corrected doublet lens of a nominal focal length of 200.0 mm with a measurement uncertainty of ±2.5% is presented.

31 citations


Cited by
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Journal ArticleDOI
TL;DR: A new laser differential reflection-confocal focal-length measurement (DRCFM) method has high accuracy and strong anti-interference capability and theoretical analyses and experimental results indicate that the DRCFM relative measurement error is less than 10 ppm.
Abstract: A new laser differential reflection-confocal focal-length measurement (DRCFM) method is proposed for the high-accuracy measurement of the lens focal length. DRCFM uses weak light reflected from the lens last surface to determine the vertex position of this surface. Differential confocal technology is then used to identify precisely the lens focus and vertex of the lens last surface, thereby enabling the precise measurement of the lens focal length. Compared with existing measurement methods, DRCFM has high accuracy and strong anti-interference capability. Theoretical analyses and experimental results indicate that the DRCFM relative measurement error is less than 10 ppm.

37 citations

Journal ArticleDOI
TL;DR: LRCFM uses the peak points of confocal response curves to precisely identify the lens focus and vertex of the lens last surface and accurately measures the distance between the two positions to determine the lens focal length.
Abstract: A laser reflection-confocal focal-length measurement (LRCFM) is proposed for the high-accuracy measurement of lens focal length. LRCFM uses the peak points of confocal response curves to precisely identify the lens focus and vertex of the lens last surface. LRCFM then accurately measures the distance between the two positions to determine the lens focal length. LRCFM uses conic fitting, which significantly enhances measurement accuracy by inhibiting the influence of environmental disturbance and system noise on the measurement results. The experimental results indicate that LRCFM has a relative expanded uncertainty of less than 0.0015%. Compared with existing measurement methods, LRCFM has high accuracy and a concise structure. Thus, LRCFM is a feasible method for high-accuracy focal-length measurements.

17 citations

Journal ArticleDOI
TL;DR: A method for measuring the focal length of the lens by a Fizeau interferometer based on the Gaussian imaging equation and the longitudinal displacements of the object point and image point and a precise formula for focal length calculation is deduced.
Abstract: A method for measuring the focal length of the lens by a Fizeau interferometer is proposed. Based on the Gaussian imaging equation and the longitudinal displacements of the object point and image point, a precise formula for focal length calculation is deduced. The longitudinal displacement of the object points is determined by the wavefront difference method with a subnanometer resolution. An experimental system for focal length measurements is set up to verify the principle. The sources of uncertainty in measurement are discussed. Both the positive and negative lens experimental results indicate that the measurement accuracy is less than 0.16% under normal experimental environment.

14 citations

Journal ArticleDOI
TL;DR: It is shown that the proposed method for measuring the focal length and distortion of optical systems using a diffraction grating provides sufficiently accurate results for many practical applications; therefore, it is appropriate for laboratory testing and for industrial applications.
Abstract: The paper presents an experimentally simple, accurate, and inexpensive method for measuring the focal length and distortion of optical systems using a diffraction grating, where both of the properties are determined from the transversal distances of diffraction maximums in one measurement. The proposed approach does not require any special components or any expensive equipment. A detailed theoretical analysis is performed, and the estimation of uncertainties is studied as well. Afterward, the method is demonstrated with a computer simulation and experimental measurement, and compared with commercially available measurement devices. It is shown that the method provides sufficiently accurate results for many practical applications; therefore, it is appropriate for laboratory testing and for industrial applications.

13 citations

Journal ArticleDOI
TL;DR: In this paper, a focal length measurement method by fiber point-diffraction longitudinal interferometry is proposed by applying two different longitudinal displacements for the object point respectively and measuring the corresponding displacements of the image point, the lens focal length is derived by Newton formula.

12 citations