Birefringent Interferometer Research Articles

Fourier approach to absolute spectroradiometry

The application of Fourier spectroscopy to absolute spectroradiometry in the visible region is discussed, and a description is given of a quartz birefringent interferometer developed for this purpose. The instrument has been used to measure the spectral transmittance of several broadband filters and to intercompare the relative spectral responsivities of two silicon photodiodes. Preliminary measurements of the spectral transmittance of the interferometer are also presented.

A new technique for the measurement of ternary molecular diffusion coefficients in liquid systems

AbstractA double Savart plate birefringent interferometer was used to study the diffusional behavior of the ternary system. Acetone (1) – Benzene (2) – Methanol (3). The ternary diffusion coefficients were measured at 9 composition points covering the entire ternary diagram. The binaries forming the borders of the ternary diagram were also studied. The ternary diffusion coefficients at one composition point of the ternary system Actone (1) – Benzene (2) – Carbon tetrachloride (3) were measured and compared with previously reported data of Cullinan and Toor(18), obtained by diaphragm cell method. Validity of the birefringent interferometric measurements when applied to the ternary liquid systems was confirmed through this comparison.

Return-pass Birefringent Fabry-Pérot Filters

Filters are proposed which use a single birefringent Fabry-Perot interferometer and a return pass. For a successful device, the birefringence of the cavity material must be high but not out of the range of available materials. Systems employing either linear or circular birefringence are discussed.

On the composition of martian surface materials

Observations were made of Mars with the birefringent interferometer. These observations when combined with spectra of the Sun show that Mars has an extremely strong band at 3.1 μ. This band is presumably produced by hydrated minerals on the surface of Mars. A search was also made for the limonite band at 8800 Å with a photoelectric spectrometer. This band had a depth which was at most only 2% to 3%. Because of the weakness of this band iron oxides are not considered to be the primary constituent of the surface material.

Infrared Interferometric Spectroscopy of Stars and Planets from 1.9 μ to 4.0 μ

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Infrared Interferometric Spectroscopy of Stars and Planets from 1.9 μ to 4.0 μ Boyce, Peter B. ; Sinton, William M. Abstract The infrared birefringent interferometer described in the paper by Sinton and Boyce has been used on the 69-in. teiescope of the Ohio Wesleyan and Ohio State Universities at Lowell Observatory and on the 200-in. telescope of the Mount Wilson and Palomar Observatories during the past two years. Over 250 interferograms have been obtained of more than 40 stars and the four bright planets. The majority of spectra extend from 1.9 P to 2.5 P. Cooling the lead sulfide detectors with liquid nitrogen extends the range to 4.0 P but with reduced sensitivity. The maximum resolution is 20 cm~1. The interferograms have been processed on an IBM 7094 computer. It takes about 15 sec to compute both the unapodized and linearly apodized spectra from one interferogram. The computed spectrum of o Ceti clearly shows the depression due to stellar water vapor lines of high rotational excitation. Six other stars, U Orionis, K Leonis, T Cephei, K Cassiopiae, x Cygni, and HD 207076, show strong water absorption. One of the most prominent stellar features is the group of CO bands begining at 2.293 P. The strength of this group shows a variation with spectral class, first appearing at KS III and increasing in strength toward later classes. The spectrum of P Cephei (M2 Ia) shows stronger CO bands than p Peg (M2 III) and also shows stellar water vapor absorption which does not appear with this strength until M6 in the giants. The spectra of seven carbon stars show much smaller CO bands than would be expected for their spectral class. With an integration time of 2 sec per point, which correcponds to 20 min per interferogram, the limit for the interferometer on the 69-in. telescope is at Johnson infrared magnitude K = 0 for dry ice cooling. Thus, more than 100 stars are bright enough to give reasonably good spectra with the present instrument. It is felt that interference spectroscopy has proved to be a valuable and practical technique for recording infrared spectra. This program has been in part supported by the National Science Foundation. Publication: The Astronomical Journal Pub Date: 1964 DOI: 10.1086/109440 Bibcode: 1964AJ.....69R.534B full text sources ADS |

Recent infrared spectra of Mars and Venus

Infrared spectra of Mars and Venus are discussed with regard to the composition of these two planets' atmospheres. The evidence for carbon monoxide in the Venus atmosphere is presented. The transparency of the Venus cloud level is found to be less than 0·1 per cent between 3 and 4 μ. Spectra of Mars are analyzed for the CO 2 content of that planet's atmosphere. A new instrument, a birefringent interferometer that has just been put into operation, is described briefly.

Some Quantitative Measurements of Path Differences and Gradients by Means of Phase Contrast and New Interferometric Devices*

The phase contrast method has initiated much work in microscopy, and outside this field we have applied it in the design of a differential refractometer for gases and liquids. This instrument has undergone modifications during the last few years and is now applicable for registration of streaming liquids and measurements of stationary fluids (E. Djurle). With the electronics operating as a null indicator the analysis of heavy water in ordinary water is made possible within 0.001%. For phase gradients within a cell containing liquids the phase contrast method presents some difficulties; an ideal solution is the birefringence interferometer proposed by Jamin but in the shape now advised by Francon. It is shown how this method is applied for accurate registration of a gradient by means of an electronic null method, and for the specific information required for obtaining diffusion constants with extremely simple methods. An isotropic compensator for microscopy has been introduced (L. Johansson), by means of which measurements are made on biological specimens rapidly and accurately that the accuracy by a color-matching method based on this compensator comes out to plus or minus 10 A (L. Johansson-B. Afzelius).