The present invention relates to an optical device, and more particularly, is related to attachments of optical components to an optical device.
A Faraday isolator is an optical isolator that transmits light in a certain direction while blocking light in the opposite direction. Faraday isolators are generally based on Faraday rotators that impart a magneto optical effect upon light transmitted through them.
Faraday isolators are often used in laser systems, for example, as described by EPO patent application number EP 1660931 B1 entitled “Faradayrotator.” As shown by
An outgassing Faraday isolator may cause contamination of any optical components in the laser and therefore worsen performance or diminish the lifetime of the laser. This is especially true for ultraviolet (UV) lasers and/or high power lasers. Therefore, there is a need in the industry to address one or more of these shortcomings.
Embodiments of the present invention provide a glue free Faraday isolator. Briefly described, the present invention is directed to a glueless optical device includes a housing having a first optical portal and a second optical portal opposite the first optical portal. A first optical component is within the housing adjacent to the first optical portal, and a second optical component is within the housing adjacent to the second optical portal. A central optical component is positioned within the housing between the first optical component and the second optical component. A first holder is configured to mount the first optical component to the housing via a first plate spring, and a second holder is configured to mount the second optical component to the housing via a second plate spring. A construct having a tubular spring, for example, a coil spring engaging a cylindrical crystal, is configured to pass through a bore hole in the central optical component and mount the central optical component between the first holder and the second holder.
Other systems, methods and features of the present invention will be or become apparent to one having ordinary skill in the art upon examining the following drawings and detailed description. It is intended that all such additional systems, methods, and features be included in this description, be within the scope of the present invention and protected by the accompanying claims.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
The following definitions are useful for interpreting terms applied to features of the embodiments disclosed herein, and are meant only to define elements within the disclosure.
As used within this disclosure, an “optical component,” refers to an object that receives electromagnetic radiation as an input and conveys the received electromagnetic radiation with generally one or more modified characteristic as output, for example but not limited to, a lens, a filter, a polarizer, a collimator, and a magneto optical crystal.
As used within this disclosure, a “plate spring,” or a “flat spring,” refers to a sheet of material, typically metal, for example, steel, having flexibility, compressibility, and deformability qualities determined, for example by the thickness and width of the material, rather than the shape of the spring as configured. For example, a flat spring may be formed of a planar piece of metal that is shaped, for example by cutting, bending, punching holes, into a form where the spring is conformed to interact in a desirable manner with another object.
As used within this disclosure, a “mechanical fastener” or “mechanical attachment” refers to a non-adhesive means for attaching a first object to a second device, for example, a clip, a clamp, a screw, a bolt, a friction fit, a tab-in-slot, a peg, a hook and loop fastener. A mechanical fastener/attachment explicitly excludes glue and other chemical adhesives, or other adhesives that may result in decay and/or deterioration resulting in outgassing from the adhesive material.
As used within this disclosure, “substantially” means “very nearly,” or to within normal manufacturing tolerances as recognized by a person having ordinary skill in the art. The term is used to allow for a reasonable amount of variation within tolerances expected in the field of use of the invention.
As used within this disclosure, “light” refers to electromagnetic radiation, including visible light and non-visible light, for example but not limited to, ultraviolet (UV) light and infrared (IR) light.
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. Embodiments of the present invention include a glue free Faraday isolator including magneto optical material and polarizers, both affixed within a housing by mechanical means, for example, via springs, instead of glue.
As shown by
The embodiments described herein may have a symmetry of elements at opposite ends of the device, for example, the first polarizer 210a disposed at the light ingress end of the Faraday isolator 200, and the second polarizer 210b disposed at the light egress end of the Faraday isolator 200. The first and second polarizers 210a, 210b will be referred to collectively herein as the polarizers 210, or referred to generically as a polarizer 210. Other components having input/output pairs will be referred to herein in a similar manner.
The polarizers 210, are each secured to the housing 250 and/or a holder 260 by a spring 220 made out of a metal plate, for example, a flat spring or a plate spring, as shown in
Two or more clamp portions 322 of the spring 220 may be bent inward toward the polarizer 210, such that the interior side 301 of the clamp portions contact and exert a spring force upon the polarizer 210, holding the polarizer 210 in place. A through port 325 may be formed in the spring 220 passing between the interior sided 301 and the exterior side 302 by removing a portion of the spring 220 to provide a window for light to pass through the spring to and/or from the polarizer 210. While the through port 325 is depicted as circular in shape, other shapes for the through port 325 may be chosen to suit the application, for example, but not limited to, a square window. Similarly, the through port 325 may be divided into two or more sections or portals. The through port 325 may be configured to accommodate another optical component (not shown), for example but not limited to, a lens or a filter.
Two wing portions 324 of the spring 220 may extend outward from the through port 325. The wing portions 324 may be used to fasten the spring 220 to another component of an optical device, for example, a holder 260 (
Under the first embodiment, the polarizers 210 are configured in a cube shaped arrangement. However, in alternative embodiments one or more of the polarizers 210 may be configured in other ways, for example, in a cylindrical (or cuboid) configuration, or other shapes, and the spring 220 may be adapted accordingly to receive and secure the configuration of the polarizer 210.
The spring 220 is preferably formed from a material, for example 1.4310=X10CrNi18-8=AISI/ASTM/UNS 301, configured to exert sufficient pressure upon the polarizer 210 without affecting the optical properties of the polarizer 210, and to securely maintain the polarizer 210 across a functional range of temperatures, where the polarizer 210 may expand and/or contract accordingly without resulting in excessive force upon the polarizer 210, or insufficient force upon the polarizer 210, for example, where the polarizer 210 is no longer secured by the spring 220.
The spring 220 may be attached to the holder 260 (
The polarizer holder 260 may be configured to physically conform to the housing 250, for example having an exterior profile shape matching an interior profile shape of the housing 250 or a beam protection ring 255 (
When compared to transmission via polarizers 210 without any mounting, the extinction and transmission of characteristics of the polarizers 210 mounted as per the first embodiment yield no measurable differences, indicating spring 220/holder 260 combination does not induce significant stress to the polarizer 210.
As shown in
The first coil spring 275a is disposed at a first end of the tube crystal 270, and may be compressed or partially compressed between the first end cap 430a and the tube crystal 270 after assembly with the second coil spring 275b and the second end cap 430b. Likewise, the second coil spring 275b is disposed at a second end of the tube crystal 270, and may be compressed or partially compressed between the second end cap 430b and the tube crystal 270, positioning the tube crystal 270 substantially at the center of the magnetics 245c (
Referring to
The housing 250, the holders 260, the beam protection rings 255 the tubular housing 420, and the end caps 430a-b are preferably formed of a structurally rigid material that is magnetically neutral, for example but not limited to aluminum or ceramic. The coil springs 275 may be formed of metal, for example, steel springs (1.4310=X10CrNi18-8=AISPASTM/UNS 301), or may be formed of a magnetically neutral material, for example, a plastic or ceramic material, provided such material is not prone to outgassing.
Referring to
The crystal support construct 400 ensures that the tube crystal 270 is positioned in the center of the primary optical component 240. It may be desirable for the tube crystal 270 to have tilted end faces, for example, having up to a 1° tilt angle or more with respect to normal from a center axis of the crystal. An advantage of the coil springs 275 over other means for supporting the tube crystal 270 is that the coil springs 275 structurally adapt to this tilt angle.
The crystal support construct 400 including the tube crystal 270 and springs 275 may flexibly support the tube crystal 270 within the magnetics 245a-c between the polarizers 210 such that the tube crystal 270 may expand or contract slightly within the magnetics 245 of the primary optical component 240, for example due to temperature changes, while still being correctly functionally positioned within the Faraday rotator magnetics 245.
Light exiting from the first polarizer 210a is conveyed through the primary optical component 240 to the second polarizer 210b. Specifically, light, for example, laser light, is received through a first optical portal 201 by the first polarizer 210a. The tube crystal 270 located within the axial bore hole 242 of the core magnetics portion 245c receives polarized light from the first polarizer 210a via a gap (or through channel) within the first coil spring portion 275a. Similarly, light exiting the tube crystal passes through a gap/channel in the second coil spring 275b to the second polarizer 210b.
A housing 250 (formed by a first housing portion 250a and a second housing portion 250b) configured to accommodate a primary optical component 240, for example an magnetic optical device such as Faraday rotator, is formed as shown by block 610. The interior of the housing 250 may be shaped to receive and contain the primary optical component 240. For example, magnetic portions of the primary optical component 240 may be arranged such that two or more portions repel one another by magnetic force, and the housing 250 may be configured to hold such repelling portions of the primary optical component 240 in place. A core portion 245c of the primary optical component 240 including an axial bore hole 242 passing through the core portion 245c is formed, as shown by block 620. For example the core portion 245c may include magnetics for the primary optical system 240, for example, a Faraday rotator. A construct 400 having a tube crystal 270 disposed between a first coil spring 275a and a second coil spring 245b is formed, as shown by block 630. The first coil spring 275a and/or the second coil spring 245b may be partially compressed when assembled with other components.
The tube crystal 270 may be generally cylindrically shaped, with substantially flat end portions configured at a small angle with respect to normal of the axial optical pathway 410 (
The construct 400 is positioned within the axial bore hole 242 passing through the primary optical component 240, as shown by block 640.
While the embodiments described here generally refer to a Faraday isolator, persons having ordinary skill in the art will recognize this invention may be applied to other types of devices where outgassing of glue may have detrimental effects, for example, faraday rotators, pockel cells, laser modulators, optical parametric oscillators, and diode lasers, among others. Further, alternative embodiments of the system may have only one polarizer 210, or may omit the polarizer 210 entirely.
The above described embodiments address an increasing demand on low outgassing Faraday isolators, for example, for UV or high power applications. In addition to reduction of outgassing, manufacture of the embodiments may be more efficient, for example, for handling and cleaning or for reassembling of the mechanical parts for low outgassing applications.
In the above embodiments, the tubular springs have been implemented as coil springs, having a circular shaped cross section, or another shape of cross-section, for example, a square cross section, which may correspond to the shape of a cross section of the tube crystal 270, for example, a square cross section. However, other tubular spring arrangements are also possible, for example, a compressible tubular (cylindrical shaped) sleeve with a through-bore for conveying light may be formed of a compressible material, provided the material is not prone to outgassing.
While the above embodiment includes a crystal mounted by two coil springs, other configurations are possible. For example, as shown in
An interior diameter of the a wide diameter portion 821 of the multi diameter tubular housing 820 is larger than an exterior diameter of the tube crystal 270 to accommodate the tube crystal 270 within the wide diameter portion 821 of the multi diameter tubular housing 820. An interior diameter of the small diameter portion 822 of the multi diameter tubular housing 820 is smaller than the exterior diameter of the tube crystal 270, thereby preventing the tube crystal 270 from entering the small diameter portion 822, and serving to hold one end of the tube crystal 270 within the wide diameter portion 821 of a multi diameter tubular housing 820. An optical pathway passes through the first polarizer 210a, an axial gap in the first coil spring 275a, the tube crystal 270, an axial gap in the small diameter portion 822 of the multi diameter tubular housing 820, and the second polarizer 210b. The interior of the small diameter portion 822 of the multi diameter tubular housing 820 may be empty (a full or partial vacuum or filled with air or other gas), or may be filled with another material, for example, a dielectric material, or another optical component.
In other embodiments, more than one crystal may be used one after the other in the optical path, where additional coil springs may be used in the space between adjacent crystals. As shown in
Other combinations of crystals and tube configurations are possible to accommodate different combinations of optical elements. For example, a fourth embodiment may combine embodiments which may have more than one crystal within the tube. As shown in
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
Filing Document | Filing Date | Country | Kind |
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PCT/US17/32615 | 5/15/2017 | WO | 00 |