skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Simple focal-length measurement technique with a circular Dammann grating

Abstract

A novel technique for focal-length measurements with a circular Dammann grating is presented. In the back focal plane of the lens under test, a one-order circular Dammann grating with limited aperture will produce double-humped radial rings. The separation between the two lobes varies with the displacement of the observed plane from the focal plane of the lens. By searching for the position at which the separation is minimal, the focal point of the lens can be located and hence the back focal length can be determined. Experimental results demonstrated that this method is efficient and can be used effectively for a quick check of focal length.

Authors:
; ;
Publication Date:
OSTI Identifier:
20854005
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Optics; Journal Volume: 46; Journal Issue: 1; Other Information: DOI: 10.1364/AO.46.000044; (c) 2007 Optical Society of America; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; APERTURES; DIFFRACTION GRATINGS; LENGTH; LENSES; TESTING

Citation Formats

Zhao Shuai, Wen, J.F., and Chung, P.S. Simple focal-length measurement technique with a circular Dammann grating. United States: N. p., 2007. Web. doi:10.1364/AO.46.000044.
Zhao Shuai, Wen, J.F., & Chung, P.S. Simple focal-length measurement technique with a circular Dammann grating. United States. doi:10.1364/AO.46.000044.
Zhao Shuai, Wen, J.F., and Chung, P.S. Mon . "Simple focal-length measurement technique with a circular Dammann grating". United States. doi:10.1364/AO.46.000044.
@article{osti_20854005,
title = {Simple focal-length measurement technique with a circular Dammann grating},
author = {Zhao Shuai and Wen, J.F. and Chung, P.S},
abstractNote = {A novel technique for focal-length measurements with a circular Dammann grating is presented. In the back focal plane of the lens under test, a one-order circular Dammann grating with limited aperture will produce double-humped radial rings. The separation between the two lobes varies with the displacement of the observed plane from the focal plane of the lens. By searching for the position at which the separation is minimal, the focal point of the lens can be located and hence the back focal length can be determined. Experimental results demonstrated that this method is efficient and can be used effectively for a quick check of focal length.},
doi = {10.1364/AO.46.000044},
journal = {Applied Optics},
number = 1,
volume = 46,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • 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 nominalmore » focal length of 200.0 mm with a measurement uncertainty of {+-}2.5% is presented.« less
  • As the technology for manufacturing radial diffraction gratings improves, there will be increasing interest in using high-groove-density radial gratings as scales for precision interferometer-type rotary encoders. If efficiency in optical designs is to be optimized, the focusing properties of these gratings must be understood. We use analytical geometry to investigate the focusing properties of a radial diffraction grating illuminated by laser light diverging from a pointlike source. We compare the results with experiments that we performed with a state-of-the-art custom radial grating, and we obtain excellent agreement with our calculations, which improve on earlier analytical work. {copyright} 1999 Optical Societymore » of America« less
  • A transmission-grating-sampled circular dichroism absorption spectroscopy (TGS-CDAS) and its theoretical model are developed sensitively to measure decay dynamics of a transient spin grating (TSG). A binary transmission grating with the same period as TSG is set behind TSG. It allows only a same small part of each period in TSG measured by circular dichroism absorption effect of a probe. In this way, the zero average of spin-dependent effects measured over a whole period in TSG is avoided so that TGS-CDAS has a high sensitivity to spin evolution in TSG. Spin transport experiments are performed on GaAs/AlGaAs quantum wells. Experimental resultsmore » prove the feasibility and reliability of TGS-CDAS.« less
  • We use the laser-induced grating technique to measure the thermal diffusivity and speed of sound of hydrothermal solutions. In this noninvasive optical techniques, a transient gradient is produced in the hydrothermal solution by optical absorption from two crossed, time-coincident nanosecond laser pulses. The grating is probed by measuring the diffraction efficiency of a third laser beam. The grating relaxes via thermal diffusion, and the thermal diffusivity is determined by measuring the decay of the grating diffraction efficiency as a function of the pump-probe delay time. In addition, intense pump pulses produce counterpropagating acoustic waves that appear as large undulations inmore » the transient grating decay spectrum. The speed of sound in the sample is simply the grating fringe spacing divided by the undulation period. The cell is made from a commercial high-pressure fitting and is equipped with two diamond windows for optical access. Results are presented for dilute dye/water solutions with T = 400{degrees}C and pressures between 20 and 70 MPa.« less
  • The thermal diffusivity of methanol, ethanol, and their aqueous solutions was measured at atmospheric pressure and temperature. The measurements were performed with a laser-induced thermal grating technique. The aqueous solutions have weight fractions of 20,40,60, and 80%. Systematic errors were taken into consideration, and corrections were made to the measured values. Focused laser beams were used, which notably intensify the diffracted signal, reduce the back-ground zero, and justify neglecting the heterodyne term of the diffracted signal, thus simplifying the data evaluation. hence, the accuracy of the measurements was improved significantly. The overall accuracy of the measurements is estimated to bemore » better than 1.5%.« less