Optical design of a near-infrared birefringent filter system and measurement of birefringent index of calcite at 1.56 μm

Document Type

Article

Publication Date

6-1-2001

Abstract

We present an optical design of a near-IR (at Fel15648.5 Å) birefringent filter system that is used to form a magnetograph to obtain chromatic images of the sun and measure the solar magnetic field at the Big Bear Solar Observatory (BBSO). This magnetograph consists of an interference prefilter, a polarization analyzer, a wavelength-tunable birefringent filter, and a Fabry-Perot Etalon. This system is expected to achieve a clean narrow pass band of 1/8 Å. It can also be tuned across the spectral line to obtain line profiles of 2-D fields of view. During the design of the tunable near-IR birefringent filter and the testing of its components, we found that the value of the birefringent index μ(ne - no) of calcite at a spectral range near 15648.5 Å is different from the value quoted in the literature. Because the birefringent index is important for the design of optical components, the birefringent index of calcite and its thermal coefficient were measured. Test results of the four pairs of calcite plates used in the birefringent filter are presented.

Identifier

0035358704 (Scopus)

Publication Title

Optical Engineering

External Full Text Location

https://doi.org/10.1117/1.1367350

ISSN

00913286

First Page

1016

Last Page

1023

Issue

6

Volume

40

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