Two-wavelength holographic interferometer

Lam, Philip; Gaskill, Jack D.; Wyant, James C.

doi:10.1364/ao.23.003079

Cited by 24 publications

(4 citation statements)

References 3 publications

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“…The angle θ is plotted as a function of λ 1 according to Eqs. (5) and 6 (red curve) and 0.5 χ = (blue curve). Each curve simulates the experimental procedure through which δα is readjusted as λ 1 is changed in order to keep the same value of χ.…”

Section: Interferogram Positioning and Distance Between Planesmentioning

confidence: 99%

“…Due to the employ of fringe pattern evaluation procedures [1][2][3] such as phase shifting and phase unwrapping, whole-field interferometric methods, like holography [4][5][6] and DSPI [7,8] (digital speckle pattern interferometry), enable fast and precise reconstruction of wavefronts as a whole with a precision up to λ/100 in cases of low optical noise [9]. The rotation-source [10,11] and the heterodyne (two-color or multi-wavelength) methods [12][13][14] are among the most promising interferometric whole-field techniques for surface contouring.…”

Section: Introductionmentioning

confidence: 99%

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Positioning and localization of two-wavelength interferograms for wavefront reconstruction  with volume holographic media

Barbosa¹

2010

Opt. Express

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This work studies both theoretically and experimentally the formation of the contour interference patterns generated by a two-wavelength real-time holographic interferometer. The resulting contour interference fringes are due to the intersection of the measured surface with parallel, equally spaced planes of constant elevation. The theoretical analysis describes how the spatial frequency of the elevation planes, their angular position, and the localization of the fringes depend on parameters of the optical setup. A theoretical model for fringe localization is developed and confirmed by the experiments, showing a strong dependence of the interferogram position on the slope of the studied surface. Due to the thick Bi(12)TiO(20) crystal employed as the storage medium the Bragg selectivity of the holographic readout is also considered.

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Section: Interferogram Positioning and Distance Between Planesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Positioning and localization of two-wavelength interferograms for wavefront reconstruction  with volume holographic media

Barbosa¹

2010

Opt. Express

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“…They also have a very fast turnaround time. Photorefractive crystals have a lot of potential as a high-resolution recording medium (Lam et al, 1984;Uhrich and Hesselink 1988); however, the optical setup is more complex, and getting a high-quality crystal is not as easy as getting other recording materials. A very promising recording medium is the use of high-resolution detector arrays or charge-coupled device (CCD) cameras to record a hologram directly.…”

Section: Interferometers Using Real Hologramsmentioning

confidence: 99%

Testing of Aspheric Wavefronts and Surfaces

Malacara

Creath²,

Schmit

et al. 2006

Optical Shop Testing

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Aspheric wavefronts with spherical aberration are produced by optical systems using spherical as well as aspherical surfaces. Aspheric surfaces are used in optical systems in order to improve aberration correction and, frequently, to decrease the number of optical elements needed to make this correction satisfactorily. However, if these surfaces are tested while being isolated from the rest of the optical system to which they belong, they frequently produce aspherical wavefronts. The interferometric testing and measurement of aspherical wavefronts are not as simple as in the case of spherical or flat wavefronts.To test aspherics, often a null test is issued. The usual definition of a null test is that which produces a fringe-free field when the desired wavefront is obtained. Then, if a tilt between the wavefront under test and the reference wavefront is added and the paraxial curvature of them are equal, straight and parallel fringes are obtained. Under these conditions, any deviation from straightness of the fringes is a graphical representation of the wavefront deformation. This is the ideal testing procedure because the desired wavefront is easily identified and measured with high accuracy. There are several methods to obtain this null test, but sometimes this is not simple and may even be a source of possible errors.Typically, if a quantitative retrieval of the wavefront is desired, the interferogram is imaged onto a CCD detector. Then, the straightness of the fringes for a perfect wavefront is useful but not absolutely necessary. However, the minimum fringe spacing should be larger than twice the pixel size in the detector. This is the wellknown Nyquist condition, which may be impossible to satisfy if the wavefront has a strong asphericity.In a Fizeau or Twyman-Green interferogram, a strong rotationally symmetric aspheric wavefront has many fringes when taken at the paraxial focus setting as shown in Figure 12.1(a). By adding a small curvature to the wavefront, that is, by adding defocusing, the minimum fringe spacing can be slightly reduced. For

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“…There have been many reports of shape measurement using digital holography, [1][2][3] but techniques are needed to measure heights that exceed the wavelength of light. Many methods for phase unwrapping 4,5) and two-wavelength methods [6][7][8] have been proposed for the shape measurement of objects larger than the wavelength of the light source used in interferometry and digital holography. [9][10][11][12][13] A digital holographic method with lateral views for dynamic-shape changes of a solder paste has been proposed.…”

Section: Introductionmentioning

confidence: 99%

Digital holography with a set of two close wavelengths for height measurement of solder bumps

Ishigaki

Mamiya²,

Hayasaki

2020

Jpn. J. Appl. Phys.

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Digital holography with two wavelengths that are close to each other is applied to the height measurement of solder bumps having a spherical specular surface and a height of several tens of micrometers. To meet industrial requirements, the error should be less than about 1 μm, and therefore the two wavelengths should have a difference of just a few nanometers for digital holographic measurement. In this research, an optical system in which two beams with wavelengths that are close to each other travel in opposite directions when they enter and exit the interferometer was developed for the first time. The main feature of the optical system is that it requires no special optical element for separating the two wavelengths. In this paper, we describe the position calibration of two cameras that support two-wavelength measurement, the accuracy evaluation of the digital holography, and the height measurement of the solder bumps. © 2020 The Japan Society of Applied Physics 2.2. Digital holography with two-wavelength method Digital holography using the two-wavelength method is reviewed here. First, interference fringes are captured with two wavelengths λ 1 and λ 2 , respectively. Two

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Two-wavelength holographic interferometer

Cited by 24 publications

References 3 publications

Positioning and localization of two-wavelength interferograms for wavefront reconstruction  with volume holographic media

Positioning and localization of two-wavelength interferograms for wavefront reconstruction  with volume holographic media

Testing of Aspheric Wavefronts and Surfaces

Digital holography with a set of two close wavelengths for height measurement of solder bumps

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Two-wavelength holographic interferometer

Cited by 24 publications

References 3 publications

Positioning and localization of two-wavelength interferograms for wavefront reconstruction with volume holographic media

Positioning and localization of two-wavelength interferograms for wavefront reconstruction with volume holographic media

Testing of Aspheric Wavefronts and Surfaces

Digital holography with a set of two close wavelengths for height measurement of solder bumps

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Product

Resources

About

Positioning and localization of two-wavelength interferograms for wavefront reconstruction  with volume holographic media

Positioning and localization of two-wavelength interferograms for wavefront reconstruction  with volume holographic media