Measurement of refractive index profile of GRIN glasses
25 Sep 2001-Vol. 4417, pp 483-488
TL;DR: In this paper, a method for measurement of refractive index profile of a GRIN system is developed based on a longitudinal interferometer using a birefringent lens, the fringe pattern so generated is made to traverse through the sample under test.
Abstract: A method for measurement of refractive index profile of a GRIN system is developed based on a longitudinal interferometer using a birefringent lens. The fringe pattern so generated is made to traverse through the sample under test. The modification of the fringes gives a measure of the refractive index profile. The fringe patterns both in presence and absence of the test samples are grabbed by a CCD camera and further processed by a computer. The basic software required for the same is being developed. Some experimental results are presented.
Citations
More filters
TL;DR: Two groups of periodic sinusoidal segments recorded by a fast complementary metal-oxide semiconductor camera are modified, and their associated phases are derived with the unique technique, and the refractive index can be obtained.
Abstract: A linearly/circularly polarized heterodyne light beam coming from a heterodyne light source with an electro-optic modulator in turn enters a modified Twyman–Green interferometer to measure the surface plane of a GRIN lens. Two groups of periodic sinusoidal segments recorded by a fast complementary metal-oxide semiconductor camera are modified, and their associated phases are derived with the unique technique. The data are substituted into the special equations derived from the Fresnel equations, and the refractive index can be obtained. When the processes are applied to other pixels, the full-field refractive-index distribution can be obtained similarly. Its validity is demonstrated.
9 citations
TL;DR: In this article, an approach to the selection of glasses for the formation of GRIN structures was proposed and verified using a set of designed glasses and numerical simulation of the structures, where concentration dependences of the diffusion coefficient (diffusion nonlinearity) of the glasses were determined and studied.
5 citations
15 Jun 2009
TL;DR: In this article, an alternative method for measuring the refractive index distribution of a GRIN lens is presented based on the Fresnel's equations and the heterodyne interferometry.
Abstract: Based on the Fresnel’s equations and the heterodyne interferometry, an alternative method for measuring the refractive index distribution of a GRIN lens is presented. A light coming from the heterodyne light source passes through a quarterwave plate and is incident on the tested GRIN lens. The reflected light passes through an analyzer and an imaging lens; finally it enters a CMOS camera. The interference signals produced by the components of the s- and the p-polarizations are recorded and they are sent to a personal computer to be analyzed. In order to measure the absolute phases of the interference signals accurately, a special condition is chosen. Then, the interference signals become a group of periodic
4 citations
Cites methods from "Measurement of refractive index pro..."
...Although several techniques [1-5] have been proposed for measuring refractive index, almost all of them are suitable only for one-point measurement....
[...]
TL;DR: Based on the Fresnel's equations and the phase-shifting method, an alternative method for measuring the refractive index distribution of a GRIN lens is presented in this article, where an electro-optical modulator is used as a phase shifter.
Abstract: Based on the Fresnel's equations and the phase-shifting method, an alternative method for measuring the refractive index
distribution of a GRIN lens is presented. A linearly/circularly polarized light in order enters a modified Twyman-Green
interferometer, in which an electro-optical modulator is used as a phase shifter. In the interferometer, the light beam is
divided by a beam-splitter into two beams, a reference beam and a test beam. After they are reflected by a plane mirror
and the tested GRIN lens, respectively, they are combined together and pass through an analyzer. The analyzer extracts
the same polarized components to interfere each other, and the
full-field interference signals produced by the
components of the s- and the p-polarizations can be obtained. The full-field interference signals are taken by a CMOS
camera. The phase differences can be obtained by using the four-step phase-shifting interferometric method. Substituting
these two groups of data into special equations derived from Fresnel equations, and the two-dimensional refractive index
distribution of the GRIN lens can be calculated. Its validity is demonstrated and has some merits such as simple optical
configuration, easy operation and high resolution.
1 citations
Cites background from "Measurement of refractive index pro..."
...Several apparatus [3-9] have been developed to measure the two-dimensional refractive index of the optical waveguide or the GRIN lens, and they have good results....
[...]
TL;DR: In this article, an alternative method for measuring the index profile of the GRIN lens is proposed based on Fresnel's equations and the common-path phase-shifting interfermetry.
Abstract: An alternative method for measuring the index profile of the GRIN lens is proposed based on Fresnel's equations and the common-path phase-shifting interfermetry. A light beam composing of the right- and the left- circularly polarized components is obliquely incident on the tested GRIN lens and the reflected light passes through an analyzer. The light is collected and imaged by an imaging lens to a CMOS camera. Four interferograms under different additional phases are taken and Carre's phase-shifting method is used to calculate the full-field phase distribution. Next, the estimated data are substituted into the special equations derived from the Fresnel's equations, and the index profile of the GRIN lens can be obtained. Its validity has been demonstrated. It has both merits of the common-path interferemetry and the phase-shifting interferemetry.
1 citations
Cites methods from "Measurement of refractive index pro..."
...Although several techniques [1-5] have been proposed for measuring refractive index, almost all of them are suitable only for one-point measurement....
[...]