Interferometric Method For Measurement Research Articles

Verification of Numerical Models Used in Microelectronics Packaging Design by Interferometric Displacement Measurement Methods

Verified/predictive modeling has become an integral part of electronic packaging product development in order to reduce costs and cycle time. In this paper, interferometric displacement measurement methods are utilized to verify the validity of numerical models for microelectronics packaging design. Three optical methods with submicron sensitivities are employed: moire´ interferometry, microscopic moire´ interferometry and Twyman/Green interferometry. The first two provide contour maps of in-plane displacement fields, and the third maps out-of-plane displacement fields. Their high sensitivity and high spatial resolution make them ideally suited for verification of numerical models. By combining numerical modeling and experimental verification until the results merge, numerical models become more accurate and dependable. Then, the models can be applied extensively to optimize the package designs with confidence that the models provide effective information on material and geometry sensitivity.

Interferometric measurement of femtosecond pulse distortion by lenses

An interferometric method for measurement of femtosecond pulse distortion caused by lenses is described. The linear method allows measurements at low intensity with precision approaching 1 fs. Data for several high numerical aperture microscope objective lenses are presented showing single pass wavepacket distortion between 9 and 18 fs.

Direct interferometric measurement of the holographic lens wave aberration

Classical interferometric methods for measurement of wave aberrations of holographic lenses have certain drawbacks. The limited diffraction efficiency of such lenses is the reason. To overcome this problem a new type of interferometer is suggested. The holographic lens under test is a basic element of the interferometer itself. The interference pattern is formed by adding the undiffracted and the diffracted waves.

Nonincremental interferometric fiber-optic measurement method for simultaneous detection of temperature and strain

A nonincremental interferometric fiber-optic measurement method for simultaneous detection of temperature and strain is reported. The method is based on the joint evaluation of the fiber-optical path length and of the fiber dispersion by means of nonincremental interferometric phase readings at two different wavelengths. The joint use of a low-coherence source and of multiple optical filtering of the interference term permits effective setting up of the method. The experimental results prove a strain measurement precision of approximately 10 micro m in the presence of temperature variation of 30 degrees C.

Interferometric method for concurrent measurement of the thermo-optic coefficients of quartz retarders

We present and discuss a Fabry-Perot type interferometric method that permits the concurrent measurement of the thermo-optic coefficients of quartz retarders in the thermal range 25-300 degrees C. The magnitude of both the coefficients is found to increase slightly with increasing temperature.

Simplified dye jet nozzle construction and interferometric method for jet thickness measurement

A jet nozzle construction is presented which is characterized by highest jet quality and simple design. The jet produced when using the nozzle in conjunction with a circular system of original construction is analysed for quality. An interferometric method for jet thickness measurement is outlined and used to measure the thickness of the jet. This method proves to be very useful in measuring the thickness of jets formed by other techniques (such as the one described by Bedard et al.). Some performance parameters of a dye jet laser pumped by a quasi-CW CuBr laser are given.

Interferometric method for concurrent measurement of thermo-optic and thermal expansion coefficients

A Fabry-Perot-type interferometer is described that permits the concurrent measurement of the coefficient of thermal expansion (alpha) and the thermooptic coefficient (dn/dT) of transparent materials. Measurements of the a and the dn/dT of vitreous silica and a heavy-metal fluoride glass show that the technique is accurate, reproducible, and easily performed. In addition, the technique is used to show that the dn/dT of heavy-metal fluoride glasses is negative and temperature dependent. The magnitude of dn/dT is found to increase with increasing temperature.

Single-mode fiber diameter measurements using Lloyd’s mirror

An interferometric method for measurement of the fiber outside diameter with an uncertainty of <1 microm is proposed and experimentally demonstrated. The fringe pattern produced by placing the fiber in contact with a reflecting surface is utilized.

干渉じま計数方式による長尺端度器の測定

Interferometric measurement method is described of long-gauge blocks using a fringe-counting interferometer with a 633-nm wavelength-stabilized He-Ne laser. Two sub-gauges, which are made of usual gauge blocks with V-type graduation lines, are optically-contacted with the both sides of a long-gauge block. Using the NRLM 2-m line standard automatic measuring-machine, several gauge blocks up to 1 m are measured with a resettability of 50 nm, and they are also measured by using a traditional excess-fractions method. The result shows that this new method can determine the length of gauge blocks up to 2 m, within an accuracy of 0.15 μm.

An interferometric method for measurement of the thermal conductivities of solids

An interferometric method is described for the determination of small deformations of a solid surface when heated by a c.w. gaussian laser beam, from which temperature increase and thermal parameters can be derived. A discussion of the method is presented and applied to the measurement of thermal conductivity, for two different situations of an unrestrained or restrained sample heated with a c.w. laser. Experimental results are finally given for a semiconductor crystal of Si.

Interferometric Measurement Method of Ultrasonic Attenuation in Small Liquid Samples

A description and validation of a system to measure ultra- sound attenuation in small samples of biological liquids using a contin- uous wave method is presented. It has been coupled to an existing velocity measurement apparatus. A two-transducer interferometric method is used. The specimen under study is placed in a triangular shaped prismatic sample holder immersed in a reference liquid. The sample holder is moved perpendicular to the ultrasonic beam in order that the acoustic path length m the sample varies. The transmitted and received signals are cross-correlated using an analog correlator com- posed of a mixer followed by a low-pass filter. The output of the correlator is plotted on an X- Y recorder while the sample holder moves across the acoustic beam. A modeling of the system has been achieved so that the attenuation coefficient can be computed numeri- cally from the data read on the recorded curves. In order to validate the method, experiments have been made with two test-liquids: Dow Corning no. 7 10 silicone oil and castor oil. The results are in good agreement with the literature. The reproducibility of the method (about 10 percent) is good in view of the small dimensions of the sample (8 cm3) and the limitations in the performance of the mixer in the high-frequency range.

Interferometric method for chromatic dispersion measurement in a single-mode optical fiber

Chromatic dispersion of a single-mode optical fiber only 1 m long is measured by a newly proposed interferometric method. Interference fringes are produced by two laser beams, one transmitting through the fiber and the other through air. Path length shifts in an interferometer for attaining the visibility maximum are measured by varying optical source wavelengths between 818 and 904 nm. Group delay time differences around 1 ps are measured. The measured results are in good agreement with those measured by the conventional pulse method for the identical 1.3 km long fiber.