Reducing the stray light of holographic gratings by shifting the substrate a short distance in the direction parallel or perpendicular to the exposure interference fringes

2017 ◽  
Vol 15 (10) ◽  
pp. 100501 ◽  
Author(s):  
Donghan Ma Donghan Ma ◽  
Lijiang Zeng Lijiang Zeng
Keyword(s):  
Short Distance ◽  
Stray Light ◽  
Direction Parallel ◽  
Holographic Gratings ◽  
Interference Fringes

Diamond turning fabrication of an ultra-compact endoscope

2016 ◽  
Vol 5 (4) ◽  
Author(s):  
Chih-Yu Huang ◽  
Rongguang Liang
Keyword(s):  
Optical System ◽  
Low Cost ◽  
High Accuracy ◽  
Diamond Turning ◽  
Fabrication Process ◽  
Stray Light ◽  
Assembly Process ◽  
Interference Fringes ◽  
Compact Size ◽  
Endoscope System

AbstractIn this paper, we propose a technique by integrating mechanical mounts into lens elements to fulfill a self-aligned and self-assembled optical system. To prove this concept, we designed, fabricated, and tested an ultra-compact endoscope that adopts this technique. By taking advantages of the specially designed fixture and observing the interference fringes between the lens and fixture, we developed a method to minimize decenter and tilt between the two surfaces of the endoscope lens during the diamond turning fabrication process. The integrated mechanical mounts provide an easy assembly process for the endoscope system while maintaining high accuracy in system alignment. With the application of heat shrink tube as the endoscope system holder and to block stray light, the proposed endoscope system has the advantages of low cost, compact size, and high imaging quality.

Low-stray-light concave holographic gratings processed by combining the methods of photoresist hot-melting and oxygen-ion ashing

2020 ◽  
Vol 59 (13) ◽  
pp. 3942
Author(s):  
Hui-Kang Chen ◽  
Zheng-Ji Ni ◽  
Yuan-Shen Huang ◽  
Bang-Lian Xu ◽  
Da-Wei Zhang
Keyword(s):  
Stray Light ◽  
Holographic Gratings ◽  
Oxygen Ion

Interference fringes arising from strong coupling in multiple exposure thick absorption holographic gratings

1984 ◽  
Vol 62 (1) ◽  
pp. 92-96
Author(s):  
Jean J. A. Couture ◽  
R. A. Lessard
Keyword(s):  
Strong Coupling ◽  
Diffraction Efficiency ◽  
Angular Separation ◽  
Multiple Exposure ◽  
Recording Medium ◽  
Holographic Gratings ◽  
Interference Fringes ◽  
Spatial Frequencies

Multiplex holograms can generate modulated interference fringes imaged onto the surface of the recording medium whenever the N reconstructed object waves have a small angular separation. At this reconstruction stage, a strong coupling arises due to the vicinity of the recorded gratings and the small differences of their spatial frequencies. Diffraction efficiency expressions describing the effects of such a coupling are deduced.

Analytic integration of contrast transfer functions

1988 ◽  
Vol 46 ◽  
pp. 822-823
Author(s):  
Peter Rez
Keyword(s):  
Wave Function ◽  
Transfer Function ◽  
Transfer Functions ◽  
Spherical Aberration ◽  
Continuous Distribution ◽  
Objective Lens ◽  
Direction Parallel ◽  
Scattering Angle ◽  
Analytic Integration ◽  
Image Position

In high resolution microscopy the image amplitude is given by the convolution of the specimen exit surface wave function and the microscope objective lens transfer function. This is usually done by multiplying the wave function and the transfer function in reciprocal space and integrating over the effective aperture. For very thin specimens the scattering can be represented by a weak phase object and the amplitude observed in the image plane is1where fe (Θ) is the electron scattering factor, r is a postition variable, Θ a scattering angle and x(Θ) the lens transfer function. x(Θ) is given by2where Cs is the objective lens spherical aberration coefficient, the wavelength, and f the defocus.We shall consider one dimensional scattering that might arise from a cross sectional specimen containing disordered planes of a heavy element stacked in a regular sequence among planes of lighter elements. In a direction parallel to the disordered planes there will be a continuous distribution of scattering angle.

Quanitative aspects of electron diffraction using electron holography

1995 ◽  
Vol 53 ◽  
pp. 616-617
Author(s):  
E. Völkl ◽  
L.F. Allard ◽  
B. Frost ◽  
T.A. Nolan
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Software Package ◽  
Spatial Coherence ◽  
Electron Holography ◽  
Image Intensity ◽  
Interference Fringes ◽  
Complex Image ◽  
The Difference ◽  
Recorded Image

Off-axis electron holography has the well known ability to preserve the complex image wave within the final, recorded image. This final image described by I(x,y) = I(r) contains contributions from the image intensity of the elastically scattered electrons IeI (r) = |A(r) exp (iΦ(r)) |, the contributions from the inelastically scattered electrons IineI (r), and the complex image wave Ψ = A(r) exp(iΦ(r)) as:(1) I(r) = IeI (r) + Iinel (r) + μ A(r) cos(2π Δk r + Φ(r))where the constant μ describes the contrast of the interference fringes which are related to the spatial coherence of the electron beam, and Φk is the resulting vector of the difference of the wavefront vectors of the two overlaping beams. Using a software package like HoloWorks, the complex image wave Ψ can be extracted.

Silicon Fringe Sample Metrology—A Thickness Measurement Technique

2013 ◽  
Author(s):  
Mark Kimball
Keyword(s):  
Temperature Dependence ◽  
Temperature Coefficient ◽  
Measurement Technique ◽  
Thickness Measurement ◽  
Sample Thickness ◽  
Index Of Refraction ◽  
Interference Fringes ◽  
Noncontact Method ◽  
Thickness Variations

Abstract Silicon’s index of refraction has a strong temperature coefficient. This temperature dependence can be used to aid sample thinning procedures used for backside analysis, by providing a noncontact method of measuring absolute sample thickness. It also can remove slope ambiguity while counting interference fringes (used to determine the direction and magnitude of thickness variations across a sample).

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