Beam Splitters
Polarizing Beam Splitters are an optical device used in various applications to divide a beam of light into two separate beams with distinct polarization states. They are an important component in many optical systems, including microscopy, interferometry, laser systems, and telecommunications.
The basic function of a polarizing beam splitter is to transmit light of a certain polarization while reflecting light of orthogonal polarization. It splits an incoming unpolarized or randomly polarized light beam into two separate output beams: one that retains its original polarization and another that has its polarization perpendicular to the input polarization.
Polarizing beam splitters are constructed using birefringent materials or thin films that exploit the polarization-dependent reflection and transmission properties. The most common type of polarizing beam splitter is made using a combination of a dichroic prism or cube and a thin film polarizer.
The unpolarized or randomly polarized light enters the Polarizing Beam Splitter. The incoming light beam then encounters a dichroic plate, prism or cube, which is made of a birefringent material like calcite or other appropriate crystals. The crystal structure of these materials causes them to exhibit different refractive indices for light polarized parallel and perpendicular to a specific axis. In combination with the dichroic prism/cube, a thin film polarizer is often used to enhance the polarization separation. The thin film polarizer is designed to reflect one polarization state while transmitting the other.
As the light passes through the dichroic prism or cube, its polarization is split into two orthogonal components. One polarization component is transmitted through the prism/cube and the thin film polarizer, while the other polarization component is reflected by the thin film polarizer. The two polarized components of light exit the PBS as separate beams with distinct polarization states. One beam retains the original polarization, and the other beam has its polarization state rotated by 90 degrees.
Polarizing beam splitters are essential tools in optical systems where the separation or manipulation of polarized light is required. They find applications in polarimetry, imaging systems, laser setups, and other fields where precise control over polarization is necessary.
Firebird Optics offers them in both plate and cube configurations for both polarizing and non-polarizing applications. Beam splitters are constructed from high quality glass, calcite and other birefringent materials with tight tolerances on both surface flatness and quality, enabling them to be used in laser applications.
Rochon Prisms
Rochon Prisms
Firebird Optics’ Rochon Prisms or Rochon Polarizers are beamsplitters that split unpolarized light into two orthagonally polarized outputs.
The Rochon polarizer is an early optical design composed of two birefringent material prisms that are joined together. Within the first prism, both the ordinary and extraordinary beams travel in alignment along the optic axis, following the ordinary refractive index. As they enter the second prism, the ordinary beam maintains its original path without deviation, thanks to the consistent refractive index. However, the extraordinary beam experiences a change, now characterized by a lower refractive index, leading to its refraction at the interface. This results in an increased angle of refraction at the boundary between the birefringent material and the surrounding air. This configuration allows for the customization of separation angles to suit specific wavelengths as required. For a detailed reference regarding separation angles concerning standard products and various wavelengths, please consult the accompanying plot.
Firebird provides these in both Quartz and YVO4.
Rochon Polarizers: A Comprehensive Exploration
In the intricate realm of optics, Rochon polarizers represent a fascinating optical device known for their precision in controlling the polarization of light. These prisms, characterized by their birefringent properties, offer a wealth of applications across various scientific, industrial, and technological domains. In this comprehensive article, we embark on an in-depth journey into the world of Rochon polarizers, unraveling their principles, construction, applications, and the profound impact they hold in the field of optics.
Unveiling the Essence of Polarization
Before delving into Rochon polarizers, let's establish a foundational understanding of polarization. Light, as an electromagnetic wave, carries an electric field that oscillates in various directions as it propagates. Polarization refers to the orientation of these oscillations, categorized as unpolarized, linearly polarized, or circularly polarized.
The Rochon Polarizer Principle
Rochon polarizers, like many other optical devices, operate on the principle of birefringence. Birefringent materials, such as calcite or quartz, possess two distinct refractive indices for different polarizations of light. The magic of Rochon polarizers unfolds with the careful construction of two birefringent prisms joined together.
Construction Insights
The construction of Rochon polarizers involves meticulous craftsmanship:
Prism Selection
Rochon polarizers are typically fabricated from calcite crystals or quartz prisms. These materials exhibit substantial birefringence, making them ideal for precise polarization control.
Bonding Process
The two prisms are securely bonded together, aligning their optical axes. This bonding process demands precision to ensure the effectiveness of the polarizer.
Refractive Index Interaction
In the first prism, both the ordinary and extraordinary beams propagate along the optic axis under the influence of the ordinary refractive index. As they enter the second prism, the ordinary beam maintains its trajectory due to consistent refractive indices. However, the extraordinary beam encounters a shift, characterized by a lower refractive index, causing it to refract at the interface. This results in an increased angle of refraction at the boundary between the birefringent material and the surrounding medium.
Tailored Separation Angles
One of the outstanding features of Rochon polarizers is their ability to provide tailored separation angles to match specific wavelengths. This customization is instrumental in various optical applications, allowing for precise polarization control.
Versatile Applications
Rochon polarizers find applications across a spectrum of fields, including:
Polarimetry
In polarimetry, Rochon polarizers play a pivotal role in measuring the degree and orientation of polarization in light. They enable scientists to gain insights into optical properties and materials' characteristics.
Microscopy
In microscopy, Rochon polarizers enhance image contrast and quality. Researchers can examine biological specimens and materials with enhanced clarity, opening doors to new discoveries.
Spectroscopy
Spectroscopy benefits greatly from Rochon polarizers. They aid in the precise analysis of the polarization properties of light emitted or absorbed by molecules and materials, offering valuable data for scientific investigations.
Remote Sensing
In remote sensing applications, Rochon polarizers are used to capture and analyze polarized light from various sources, contributing to environmental monitoring and data collection.
Conclusion: Precision in Light Control
In the multifaceted world of optics, Rochon polarizers stand as exemplars of precision in controlling the polarization of light. Their intricate design, tailored separation angles, and versatile applications make them indispensable tools in scientific research, microscopy, spectroscopy, and beyond. As we continue to push the boundaries of optical exploration, Rochon polarizers remain steadfast companions, guiding us with their precision and unlocking new frontiers of discovery and innovation.
Specs for Rochon Prisms:
Materials available: Quartz and Yttrium Orthovanadate (YVO4)
Wavelength ranges: Quartz: 400-2300nm; YVO4: 500-4000nm
Extinction ratio: YVO4: <5x10-5; Quartz: <5x10-4
Surface Quality: 20-10 scratch/dig
Wavefront Distortion: λ/4@632.8nm
Beam Deviation: ＜3 arc minutes
Flatness: λ/4@632.8nm
Damage Threshold: >5W/cm2 CW, 1064nm
Coating: Single Layer MgF2 @1064nm
Holder: Black Anodized Aluminum
