Birefringence in a transparent material caused by stress. Infrared birefringence imaging of residual stress and bulk defects in multicrystalline silicon vidya ganapati,1 stephan schoenfelder,1,2,3 sergio castellanos,1 sebastian oener,4 ringo koepge,2,3 aaron sampson,1 matthew a. For a practical laser system, it is important to know how the induce birefringence may affect the performance of the laser. Stress induced absorption of a birefringence reduced polymer optical fiber with doped core keigo uzawa1, takamichi tozaki1, kentaro yano2, eisuke nihei3, and rei furukawa1 1department of engineering science, graduate school of informatics and engineering, the university of electrocommunications 151 chofugaoka. While birefringent effects in plastic optics are thoroughly investigated, other applications which involve plastics will benefit from this study. An inhomogeneity of the birefringence within the seam is. Probing stressinduced optical birefringence of glassy polymers by whispering gallery modes light localization karolina milenko, stavros pissadakis, georgios gkantzounis. This can also be called double refraction of light. Then, the calculated stress induced birefringence was converted into. This then allows for any arbitrary input polarization state to be rotated into any desired output polarization state. An ellipsometer was used to measure the retardation effect of static loading on a set of ceramic equilateral prisms and the stress optic coefficients were obtained. Laserinscribed stressinduced birefringence of sapphire.
First, a mathematical model was established to formulate mode dispersion caused by stress induced birefringence. Infrared birefringence imaging of residual stress and bulk. Polarization cameras take the stress out of materials analysis. Diamond belongs to the cubic crystal system and should therefore exhibit isotropic optical properties. Osa stress induced birefringence tuning in femtosecond. While most natural objects will be characterized by low dolp values, manmade objects such as plastic will have high dolp values. Femtosecond laser directwrite waveplates based on stressinduced. Geometric phase via stress induced birefringence request pdf. Second, in the stressinduced birefringence simulation model, the. Optical design and optomechanical software tools to model stress. It is a property of all dielectric media and is often used to experimentally determine the stress distribution in a material, where it gives a picture of stress distributions around discontinuities in materials. In addition to natural birefringence, stress induced birefringence is often worth paying attention to in practice.
Stressinduced birefringence in silicononinsulator soi. Interferometric analysis of stressinduced birefringence. This is especially the case for glass windows of a vacuum chamber. Pdf modeling the effects of stress birefringence is critical for polarization sensitive optical systems. Stressinduced birefringence can be particularly detrimental to the state of polarization of light when a laser. Interestingly, aolp represents the polarization angle of the light as it reaches the camera sensor. Since it is based on a liquid crystal device, there is no internal mechanical movement, leading to very stable, vibrationfree operation. About birefringence concept moldflow insight 2018 autodesk. Mar 25, 2018 however, stress induced birefringence sib of alkali halides as well as intrinsic birefringence manifest during the disk formation process. Simple method for reducing the depolarization loss resulting from thermally induced birefringence in solidstate lasers, opt.
Interestingly, aolp represents the polarization angle of. Calculations of the birefringence are compared with polarscopic measurements and display good agreement. In this study, the residual stress and birefringence of precision injection molding for microlens arrays has been studied by simulation and injection molding experiments. The main contribution in this paper is that the transmission characteristics and stress induced birefringence of the new designed c. This essentially means that solidworks plastics allows the user to see birefringence at different stages during the injection molding cycle, such as birefringence at filling end, packing end, and. In this paper we describe a technique which exploits stress induced by laser irradiation as a source of birefringence. Femtosecond laser directwrite waveplates based on stress. However, it has long been documented that diamonds often show weak birefringence. Application of the gimp software in the analysis of. While birefringence is usually obtained using an anisotropic crystal, it can result from an optically isotropic material in a few ways. In this work, we developed an easytouse methodology for birefringence image processing using the gimp opensource software. Numerical simulation of residual stress and birefringence in. Thus, the true chiroptical measurement is disturbed by optical anisotropies oa containing sib and intrinsic birefringence, except in the case of optical homogeneity. The induced birefringence is determined to be equivalent for involume irradiated track and welding seams.
Stressinduced absorption of a birefringencereduced. For a practical laser system, it is important to know how the induce birefringence. The birefringence analysis and calculation method of stressinduced pmf is given by thermal stress analysis theory and fiber polarization theory. Results of computer modeling show that a higher degree of birefringence can be obtained with the use of a larger cladding and larger stress applying zones in the fiber. Marcus,5 barry lai,6 humphrey morhenn,4 giso hahn,4 joerg bagdahn,2 and tonio buonassisi1,a.
Birefringence is an intrinsic property of many optical materials, and may also be induced by external forces applied to the material. Probing stressinduced optical birefringence of glassy. The packaging and mounting of a laser crystal into system may cause stresses. Osa stress birefringence modeling for lens design and. Birefringence induced in optical rib waveguides by thermal. Imaging optics 270 having reduced susceptibility to thermally induced stress birefringence for imaging an object plane 170, 260 to an image plane 190 comprising an aperture stop 230 located between the object plane and the image plane, a first group of optical elements 400402 located on the object plane side 260 of the aperture stop 230 and a second group of optical elements. However, stress induced birefringence sib of alkali halides as well as intrinsic birefringence manifest during the disk formation process. The stress can be caused either through twisting or rotating 1, as shown in figure 1. Optical birefringence mapping enables concrete stress. Thorlabs lcc7201 birefringence imaging system is designed for use in academic. With conventional optical design and optomechanical software tools to design these lenses, special consideration is required in choosing glass materials, coatings, and optomechanical design for low intrinsic and stressinduced birefringence and thermal stability. The fast axis of birefringence is aligned with the axis defined by the two opposite forces. The induced birefringence may be temporary, as when the material is oscillated, or the birefringence may be residual, as may happen when, for example, the material undergoes thermal stress during production of.
As a result, wrapping the fiber around the fiber spools creates independent wave plates that alter the state of polarization. The stress induced birefringence for erbium doped yttria ceramics were measured at room temperature. Stress induced birefringence is a wellused phenomenon to create arti. Color pattern of a plastic box with frozen in mechanical stress placed between two crossed polarizers. In this paper, parallel laser modification tracks with different geometries were applied. Birefringence and orientation data as computed by sigfit for arbitrary threedimensional. Pdf numerical methods to compute optical errors due to stress. Birefringence primarily occurs due to residual stress induced during the manufacturing processes especially in injection moulding and 3d printing method.
Optical glasses and plastics can have birefringence induced by mechanical stress. In addition to the characterization of the properties, the phosphate network was qualitatively and quantitatively described in terms of q 2 and q1 ratios by 1d 31p magic angle spinning nuclear magnetic resonance spectroscopy. Stressinduced birefringence of the cornea sciencedirect. Stress induced birefringence spectroscopy jku linz. Laserinscribed stressinduced birefringence of sapphire mdpi. The mechanical stress will induce birefringence in the crystal, which may slightly. The stressinduced birefringence for erbium doped yttria ceramics were measured at room temperature. Stressinduced birefringence is created by bending the fiber. Low stress soldering techniques can guarantee a minimized input of thermal energy allowing for the design and later assembly of more robust and miniaturized optical devices.
However, in order to build miniaturized optical devices, these small induced stresses produced by soldering techniques have to be investigated to guarantee that the stress induced birefringence effects do not. Stressinduced birefringence in laser crystals lighttrans. Second, in the stress induced birefringence simulation model, the finite element method was used to analyze the transmission characteristics of the hollowcore circular photonic crystal fiber. Since it is based on a liquid crystal device, there is no internal mechanical movement, leading to. Passaro photonics research group, dipartimento di ingegneria elettrica e dellinformazione, politecnico di bari, via edoardo orabona n.
Horizontally and verticallypolarized light travels at different speeds through the material. Optical birefringence mapping enables concrete stress testing. It is found that the stress induced birefringence is determined by the waveguide crosssection, the upper cladding layer thickness, and film stress levels. Thermally induced strain and birefringence calculations for a. We present a numerical study of stress induced birefringence in microstructured optical fibers mofs, using a finiteelement method. The results indicate that stress induced birefringence decreases as airhole size increase. Structural effect on stretchinduced birefringence in. Jcmsuite complete finite element technology for optical. The main methods of spectroscopy are well understood and widely used in many lines of natural sciences. Stressinduced birefringence control in optical planar waveguides. Pdf laserinscribed stressinduced birefringence of sapphire. An imaging lens having reduced susceptibility to thermally induced stress birefringence for imaging an object plane to an image plane. The spatial variance in opd caused by the stress induced birefringence is seen by a traditional interferometer as. The birefringence analysis and calculation method of stress induced pmf is given by thermal stress analysis theory and fiber polarization theory.
Stress induced birefringence tuning in femtosecond laser. When two equal and opposite forces p act across an axis of a fiber with a diameter d, the birefringence induced is linear. Lowbirefringence lens design for polarization sensitive. What causes polarised materials to change colour under stress. Rp photonics encyclopedia depolarization loss, thermally. Wo2063172a1 catadioptric imaging optics with reduced. Birefringence and orientation data as computed by sigfit for arbitrary three dimensional. Many factors contribute to birefringence in optical materials.
Using an optical imaging system that senses the stress induced birefringence of an epoxy coating placed on cement structures under load, researchers at the university of leeds leeds, england are mapping the strength of modern forms of concrete, giving the concrete industry a quantitative, 2d way to understand when a concrete structure could fracture. The measured retardance can be interpreted by stress induced birefringence related to the permanent volume expansion, photo induced by a nonspherical irradiated zone. The linear relation between stress and birefringence in polymer melts, usually expressed as stress optical rule, has been exploited for the analysis of the injection molding process and verification of simulation software mainly with respect to the flow induced. Mar 20, 1996 a numerical model is developed to determine the spatiotemporal stress induced strain distribution across the prism, indexmatching fixant, and laser rod, and the birefringence that arises from the stress induced strain within the laser rod. The polarimeter is suitable for quick investigation of largearea wafers, since the data are acquired from a dense 256 x 256 network of points giving a reasonable spatial resolution. When the tape stretches, the polymer molecules in it tend to orient or also stretch. Stressinduced birefringence in microstructured optical. Key research and development program of china and national natural. Stress birefringence results when isotropic materials are stressed or deformed i. Stress induced birefringence can be particularly detrimental to the state of polarization of light when a laser beam is transmitted through the glass. This study has focused on the causes of strain induced birefringence in natural diamonds. We further studied the effect of airhole size on the stressinduced birefringence of pcfs. Jcmsuite is the finite element solver for the computation of electromagnetic waves in complex nanooptical systems.
Results of computer modeling show that a higher degree of birefringence can be obtained with the use of a larger cladding and larger stressapplying zones in the fiber. Photoelasticity describes changes in the optical properties of a material under mechanical deformation. Furthermore, virtuallab also enables the conversion from measured stress to induced birefringence, from which the possible influence on the optical system can be analyzed. The mechanical stress will induce birefringence in the crystal, which may slightly alter the polarization of the laser beam. Femtosecond laser exposure produces form and stress birefringence in glasses, mainly controlled by laser polarization and pulse energy, which leads to challenges in certain applications where polarization mode dispersion or birefringence splitting is critical for the desired responses from optical devices. Imaging birefringence and using it to determine stress in a production environment requires a compact measurement system, high speed imaging and analysis software that can quickly process data. The continuum mechanics and heat conduction moduls allows for modeling complicated materials such as stress induced birefringence.
Optical birefringence was created in a singlemode fiber by introducing a series of symmetric cuboid stress rods on both sides of the fiber core along the fiber axis using a femtosecond laser. Us8649094b2 low thermal stress birefringence imaging lens. Stressinduced birefringence control in femtosecond laser. Tensile stress is induced in the laser scanning direction by the welding seams. Birefringent liquid crystals may be tuned to a desired polarization state with electric. Complete imaging system includes software and laptop. Birefringence induced by thermal stress in bowtie optical fibers is studied in detail by the use of the finiteelement method.
Residual stress in glass and plastic products can lead to warping, cracking and premature component aging. In this paper, we discuss the influence of several special shape cores on the birefringence value. Photoelastic experiments also informally referred to as photoelasticity are an. Stress birefringence modeling for lens design and photonics. Stressinduced birefringence is a wellused phenomenon to create. Polarization cameras take the stress out of materials. Stress induced birefringence in crystalsglassespolymers 1415, volume phase transitions 16, and complex topological structures for volumetric stress control 17, or patterning of. Pdf stress birefringence modeling for lens design and photonics. Solderjet bumping packaging technique optimization for the. The stress induced birefringence was estimated to be 2. Ansys results were later imported in virtuallab fusion software where. Then the birefringence of the circular and elliptical core fiber is studied numerically as the comparison of subsequent part.
In view of most approaches addressing smfs birefringence, it can still be used for birefringence md. Many materials exhibit some amount of birefringence either due to the materials composition or caused by external forces. Rp photonics encyclopedia birefringence, double refraction. It was found that by using the appropriate number of loops on each paddle that the stress induced birefringence can be adjusted continuously.
Optical design and optomechanical interface software tools to model stress birefringence are discussed and demonstrated for two examples. Experimental setup stress induced birefringence spectroscopy. The stress birefringence distributions of single mode fiber and airsilica based pcfs were calculated by stress photoelastic effect. Longtime relaxation of stressinduced birefringence of. The birefringence is given by sakai and kimura, 198117. Dolp is a useful measure for other reasons it can be used to analyze stressinduced birefringence in transparent materials since the birefringence of such material is directly proportional to the dolp. The first example compares the magnitude of birefringence as a function of lens shape parameters. Dolp is a useful measure for other reasons it can be used to analyze stress induced birefringence in transparent materials since the birefringence of such material is directly proportional to the dolp. There is a good agreement in the change pattern of the residual stress and birefringence distribution obtained by numerical simulation software. Thermally induced depolarization is suppressed if the gain medium has a sufficiently strong natural birefringence, so that the birefringent axis can not be significantly rotated by thermal effects. Laserinscribed stressinduced birefringence of sapphire ncbi. Birefringence induced by stress and expanding beyond laser structured regions is promising for polarisation microoptics, especially when the laser modi.
Stressinduced birefringence and fabrication of infiber. Since compensation of spatially inhomogeneous birefringence is extremely challenging, it should be prevented by proper. Flow induced birefringence is a technique with numerous potential applications in polymers, because the bright and dark fringe patterns of the birefringence images can be related to principal stress difference psd profile along the flow centerline. It measures the retardance and azimuths of flat, planar samples, such as crystals and liquid crystal devices, and is particularly wellsuited for characterizing stressinduced birefringence. Stress in a vgroove connector stress in a sleevetype connector stress birefringence in a lens stresses induced by an adhesive are minimized by using adhesives that. We demonstrate that by controlling stress distribution we can implement complex phase patterns. It measures the retardance and azimuths of flat, planar samples, such as crystals and liquid crystal devices, and is particularly wellsuited for characterizing stress induced birefringence. And we design a new leafshaped core stress induced pmf with high birefringence. The stress lacks spherical symmetry and is stronger in the direction of the nanograting 8.
The linear relation between stress and birefringence in polymer melts, usually expressed as stressoptical rule, has been exploited for the analysis of the injection molding process and verification of simulation software mainly with respect to the flowinduced molecular orientation in polystyrene ps 24. Because the relationship is linear, birefringence magnitude can be substituted for actual stress i. The reason for this is that the temperature gradients in the gain medium induce mechanical stress and thus some amount of birefringence, with the direction of the local axis varying over the beam crosssection. However, when they are under mechanical stress, birefringence results.
Quantitative stressinduced birefringence measurements of. In addition to natural birefringence, stressinduced birefringence is often worth paying attention to in practice. Interferometric analysis of stress induced birefringence in a rotating glass disk. For example, any of the following conditions can cause stress birefringence. Birefringence is an intrinsic property of many optical materials, and may also be induced by external forces. Transmission ellipsometers and analysis software were used to determine the optical axis and in. Modeling the effects of stress birefringence is critical for polarization sensitive optical systems. Investigation of stressinduced birefringence in large. Birefringence helps analyze optical telecom components. Jul 01, 2004 through fullvectorial finiteelement simulations, we investigate the variation of stress induced birefringence with waveguide core and cladding geometries.
Mofs under lateral forces and twists are considered separately. Osa stress birefringence modeling for lens design and photonics. Flow induced birefringence is created by flow induced residual stress and thermal induced birefringence is created by thermal induced residual stress. Design of high birefringence stressinduced polarization. An ellipsometer was used to measure the retardation effect of static loading on a set of ceramic equilateral prisms and the stressoptic coefficients were obtained. Even in a naturally isotropic medium, birefringence can be induced e. Analysis of the transmission characteristic and stress. Stress induced birefringence properties as evidenced by uniaxial tensile tests on strips of corneal tissue are discussed. Although birefringence is an inherent property of many anisotropic crystals, such as calcite and quartz, it can also arise from other factors, such as structural ordering, physical stress, deformation, flow through a restricted conduit, and strain. This leads to a third layer of polarizing material in the middle, or even birefringence, which makes the colors between the.
612 818 327 910 600 390 1170 99 1228 1449 602 749 622 1256 157 1281 1410 1153 324 1431 342 697 1329 1048 1446 1449 469 1064 961 1332 670 77 524 64 941 848 1431 493 677 268 621 1493 1162 519 1464 173 1368 837