Cryogenic refractometer for high accuracy measurements of the refractive index of materials

A prototype for a compact and relatively simple system capable to measure the refraction index of glasses, between 0.4 to 1.7 micron, at room and cryogenic temperatures (T=100-300 K), with an absolute precision of few parts of 100'000 has been developed at INAF facilities in Merate. It is based onto the measurement of the deviation angle of monochromatic light passing through a prism sample placed in the cryogenic chamber. The precision of the measurements depends on many factors, in particular the angle measurement and the thermal stability. Different subsystems have been studied to keep all these parameters under accurate control. One of the main issues has been the trade-off between the simplicity of the set-up and the precision of the refractive index measurement.

[1]  G. Molesini,et al.  Measuring the refractive index of vitreous materials at cryogenic temperatures with a spectrometer , 2008 .

[2]  Douglas B. Leviton,et al.  Temperature-dependent refractive index of silicon and germanium , 2006, SPIE Astronomical Telescopes + Instrumentation.

[3]  William L. Wolfe,et al.  Status Of Cryogenic Refractive-Index Measurements , 1980, Optics & Photonics.

[4]  Douglas B. Leviton,et al.  Automation, operation, and data analysis in the cryogenic, high accuracy, refraction measuring system (CHARMS) , 2005, SPIE Optics + Photonics.

[5]  Douglas B. Leviton,et al.  Thermal design considerations for the cryogenic high-accuracy refraction measuring system (CHARMS) , 2003, SPIE Optics + Photonics.

[6]  Douglas B. Leviton,et al.  Cryogenic High-Accuracy Refraction Measuring System (CHARMS): a new facility for cryogenic infrared through far-ultraviolet refractive index measurements , 2004, SPIE Astronomical Telescopes + Instrumentation.

[7]  L. J. Cox.  Ellipsometry and Polarized Light , 1978 .

[8]  Douglas B. Leviton,et al.  Temperature-dependent refractive index of CaF2 and Infrasil 301 , 2007, SPIE Optical Engineering + Applications.

[9]  A M Glass,et al.  Optical Materials , 1987, Science.

[10]  Douglas B. Leviton,et al.  Temperature-dependent absolute refractive index measurements of synthetic fused silica , 2006, SPIE Astronomical Telescopes + Instrumentation.

[11]  Douglas B. Leviton,et al.  Cryogenic high-accuracy absolute prism refractometer for infrared through far-ultraviolet optical materials: implementation and initial results , 2003, SPIE Optics + Photonics.

[12]  W. Wolfe,et al.  Cryogenic refractive indices of ZnSe, Ge, and Si at 10.6 microm. , 1991, Applied optics.

[13]  Douglas B. Leviton,et al.  High accuracy, absolute, cryogenic refractive index measurements of infrared lens materials for JWST NIRCam using CHARMS , 2005, SPIE Optics + Photonics.

[14]  Douglas B. Leviton,et al.  Cryogenic temperature-dependent refractive index measurements of N-BK7, BaLKN3, SF15, and E-SF03 , 2007, SPIE Optical Engineering + Applications.

[15]  Douglas B. Leviton,et al.  Design of a cryogenic high-accuracy absolute prism refractometer for infrared through far-ultraviolet optical materials , 2003, SPIE Astronomical Telescopes + Instrumentation.