JP2003075697A - Optomechanical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optomechanical mounting which does not requires an additional process of applying a clamping force after an optical element is positioned and keep the precise azimuth angle of an optical element. SOLUTION: A system includes a sphere 300 which is suitably fitted to contain an optical element, a 1st spring assembly composed of one or more springs 220 which abut against the sphere, and a 2nd spring assembly composed of one or more springs 620 which abut against the sphere. The 1st spring assembly has the springs corresponding to the springs of the 2nd spring assembly and the respective springs in the 1st spring assembly applies opposing force to the sphere against the force that the corresponding springs of the 2nd spring assembly applies to the sphere. All the spring forces are directed to the center of the sphere. When the optomechanical mounting is exposed to thermal variation, vibration and a shock, the opposite forces maintain the positional stability of the sphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an opto-mechanical system such as an opto-mechanical mount (opto-mechanical mount) for accurately guiding / positioning a light beam.

[0002]

BACKGROUND OF THE INVENTION Many optical systems require a precision opto-mechanical pedestal to keep the optical elements in the required positions and orientations for system operation. In order to achieve proper positioning and alignment of the optical element, the opto-mechanical pedestal must generally be allowed to move and rotate with respect to other optical elements during the aligning alignment process, but once the optical element is Once aligned, the cradle must hold the optics firmly so that proper alignment and alignment is maintained during use and shipping of the optical system. There is a conflict between the need to align the optical elements with sufficient accuracy and the need to keep the optical elements aligned for the life of the optical system.

Clamping systems are often used in opto-mechanical pedestals to be adjustable for alignment and to hold the optical elements in place. In particular, by loosening the clamps, the optics in the opto-mechanical pedestal can be adjusted, aligned and aligned, and the tight clamps hold the optics securely. In the opto-mechanical pedestal using the clamp, there may be a problem that the alignment of the optical elements is disturbed when the opto-mechanical pedestal is clamped.

Utilizing the same clamping friction when aligning optical elements and avoiding the turbulence caused by clamping after alignment, it is between the accuracy of alignment and operational stability. A compromise is needed. In particular, multi-axis interferometers generally require an opto-mechanical pedestal capable of precisely orienting the laser beam with a sensitivity below microradians. Opto-mechanical pedestals with a purely kinematic design can have sub-microradian sensitivities, but generally cannot maintain their alignment when exposed to shock, vibration, or temperature changes. . Tight clamps, and therefore stable opto-mechanical mounts, are generally difficult to adjust with submicroradian accuracy. Therefore, a compromise between tuning accuracy and stability is generally required, and quasi-kinematic design is often the product of compromise.

FIG. 1 shows an opto-mechanical pedestal 100 that emphasizes minimal restraint and adjustment sensitivity. Further, an opto-mechanical pedestal of this type is described in US Pat. No. 6,170,795. The opto-mechanical pedestal 100 includes a support 14, three spherical nests 20, a sphere 12, a top plate 24, and a preload spring plunger 26 (spring not shown) operated by a clamp screw 28. The sphere 12 includes an optical element such as a reflector (not shown) that can be rotated on the three spherical nests 20 for the alignment process that redirects the optical element without changing its optical center position. Including.

Alignment of the optics fixed in the center of the sphere 12 usually involves loosening the clamp screw 28 to release or reduce the clamping force on the sphere 12 to allow rotation of the sphere 12. is necessary. Therefore, a spring (not shown) receiver on the plunger 26 provides an initial stabilizing force directed along the radius of the sphere 12. Once the sphere 12 is aligned and aligned, clamping and tightening the clamp screw 28 causes the clamping force to prevail on the spring force and the plunger 26 to exert the clamping force, which force keeps the sphere 12 in the proper orientation. . By exerting a predetermined torque on the clamp screw 28, the final clamping force is set and the frictional force resulting from the clamping force resists the rotation of the sphere 12 and maintains the alignment of the optical elements.

[0007]

The need to loosen the clamping screws 28 before alignment and the need to clamp the clamping screws 28 after alignment increases the overall time required for the alignment process. Moreover, the clamp screw 28 is not easily accessible in the optics, which makes the alignment process more difficult. Further clamping of the clamping screw 28 causes bending of the assembly, thereby disturbing the just completed alignment and alignment accuracy. For most applications, there is a desire for an opto-mechanical pedestal that can maintain the precise azimuth angle of the optical element after the alignment process without the need for an additional process to apply a clamping force.

[0008]

SUMMARY OF THE INVENTION In accordance with one aspect of the present invention, an opto-mechanical pedestal includes an upper spring assembly and a lower spring assembly, the spring assemblies including an optical element secured at its center. Support and fix the containing sphere. By making the spring assemblies substantially identical, thermal expansion affecting one spring assembly compensates for the same opposing thermal expansion affecting the other spring assembly, providing excellent thermal stability for the opto-mechanical pedestal. It is possible to bring about sex. Frictional forces on the sphere from the upper and lower spring assemblies maintain the orientation of the sphere (and the optics within the sphere) during operation, but remove the spring assembly or increase the spring tension exerted on the sphere by the spring assembly. Allows the spheres to be rotated and aligned without being released.

Each spring assembly may include a spring that wraps around the ring, such that the central region of each assembly is open to the optical path through the assembly. Alternatively, an opening in the central region may be provided and a tool entry for facilitating rotation of the sphere for aligning the optics may be provided.

The optomechanical pedestal according to the embodiments of the present invention exhibits excellent long-term alignment stability even when subjected to temperature changes, shocks, and vibrations. The aligned state is maintained for a long time. The symmetry of the opto-mechanical pedestal and the use of similar structural materials in the pedestal components provide excellent thermal stability. The high clamping force between the spring and the sphere acts as a resistance to changes in alignment caused by mechanical shock. Friction forces, especially at multiple points on the sphere, resist rotation of the sphere after it is aligned, but the delicate finishing surfaces of the spring and sphere provide smooth, high-resolution rotation achieved by removable alignment tools. Bring adjustments. Vibration stability is achieved by a spring that is geometrically deformed and hardened as a result of high compressive forces, tightly wrapped around the sphere, with a high damping spring / mass with a high resonance frequency, usually above 3 kHz. Because it brings the system.

One particular embodiment of the invention includes a sphere adapted to mount an optical element, a first spring group including a plurality of springs abutting the sphere, and a plurality of springs abutting the sphere. It is a system including a second spring group. In general, each spring of the first spring group has a corresponding spring in the second spring group, each spring in the first spring group having a corresponding spring in the second spring group relative to the sphere. An opposing force is exerted on the sphere on the same axis as the exerted force. All spring forces go to the center of the sphere. When the opto-mechanical pedestal is exposed to heat changes, vibrations, and shocks, opposing spring forces maintain the positional stability of the sphere.

In general, both the first and second spring groups can be mounted on the inner surface of the support ring. The inner surface of the support ring has a generally truncated cone-shaped cross-section with jigs for mounting the springs, features, each spring being constant with the normal to the surface of the sphere where the spring abuts the sphere. It may be an angled leaf spring. The support ring can open the central portion for the optical path of the optical element or for access to the sphere during the alignment process. When the support ring is attached, the separation or separation distance of the support ring of the first spring group and the second spring group or related to them is controlled,
It is possible to control the magnitude of the force exerted on the sphere by the first spring group and the second spring group.

Another embodiment of the present invention is a system that utilizes a spring washer to support and exert a force on the sphere. Fewer springs are required and no features need to be provided on the inner surface of the support ring.

[0014]

DETAILED DESCRIPTION OF THE INVENTION In the following, the same reference numbers in different figures indicate similar or identical parts. According to one aspect of the invention, an upper spring assembly and a lower spring assembly support a sphere containing optical elements. Each spring assembly is substantially identical and each spring is oriented to exert a force in the radial direction of the sphere. Each of these spring forces is collinear with the opposing force provided by the corresponding spring in the other spring assembly. These spring assemblies hold the sphere in place with a high degree of thermal stability, because thermal expansion that changes the force from one spring assembly changes the opposing force from the other spring assembly. Or because it is in balance with thermal expansion.

Each spring assembly includes a spring on a support ring having a central portion of the assembly that is open for an optical path and an alignment tool entry.

FIG. 2 is a perspective view of a lower spring assembly 200 according to an exemplary embodiment of the present invention. Spring assembly 200 includes three leaf springs 220 attached to a support ring 210.

The support ring 210 is formed from a rigid material, such as tool steel, a tough material and is substantially ring-shaped, with its inner surface having a truncated conical shape for the most part. In the illustrated embodiment, the support ring has a thickness of about 14
mm and has an outer diameter of about 44.22 mm. The inner surface forms a cylindrical opening having a diameter of about 25.7 mm and a height of about 6.82 mm at the bottom of the support ring 210. The conical portion extends upward from the cylindrical opening at an angle of 45 °. The conical portion thus has an opening at the top of the support ring 210 of about 39.92 mm.

The inner surface of the support ring 210 is circumferentially 120
Jigs or features 230 for seating and attaching the leaf springs 220 are arranged at intervals of every °. In an exemplary embodiment of the invention, each leaf spring 220 has a width of about 2
It is a rectangular member made of flat metal such as spring steel with a height of 0.70 mm, a height of 12.7 mm, and a wall thickness of about 0.00762 mm. Leaf spring 220
Is flat in the exemplary embodiment of the invention, but may be convex or concave in alternative embodiments of the invention.

Each feature 230 is machined into the conical portion of the inner surface of the support ring 210 and is sized to receive the leaf spring 220. In the exemplary embodiment, feature 230 comprises flat ledges approximately 4.15 mm wide and leaf spring 220 is stitch welded.
Welded to the ledge 232 by 34, which is no longer than 4.0 mm and avoids welds extending beyond the ledge 232. The locator pin 240 is not a part of the spring assembly 200, but assists in locating the spring 220 for attachment (eg, welding) to the support ring 210, and in the exemplary embodiment, the locator pin 240 has a diameter of approximately 20.08 mm. Have. In other embodiments, other means such as epoxy or spring tension may hold the leaf spring 220 against the support ring 210 or allow the leaf spring to move freely within the feature 230 of the support ring 210. .

FIG. 3 shows the sphere 300 resting on the lower spring assembly 200. The sphere 300 includes a reflecting mirror, a beam splitter, a relay window, a wedge window, and an optical element (not shown) such as a lens. In the exemplary embodiment, sphere 300 is a precision bearing having a diameter of approximately 41.275 mm, which is machined to provide an aperture 310 for an optical element and an aperture 320 for an optical path leading to the optical element. Including. More balls 3
00 includes an opening 330 into which an alignment tool, such as a hex wrench or hex lever, utilized to rotate sphere 300 within the completed opto-mechanical cradle.

To assemble the opto-mechanical pedestal, the lower assembly 200 is attached (eg, screwed) to the base plate 410, as shown in FIG. The mounting legs of the base plate 410 are designed to flex rather than slip when the pedestal encounters different thermal expansions, for example due to temperature gradients, or when the base plate 410 is mounted to a base of different material. This reestablishes the original aligned and aligned state of the optical elements when the temperature returns to ambient temperature.

The sphere 300 is disposed on the lower spring assembly 200. The upper spring assembly 420 rests on the ball 300 and is mounted inside the cover 510 shown in FIG.
Cover 510 is attached to base plate 410 so that upper spring assembly 420 abuts ball 300 as shown in FIG.

The height of the cover 510 in FIG. 5 and the spacing between the cover 510 and the base plate 410 are such that the cover 510 and the base plate 410 have an upper spring assembly 420 and a lower spring assembly 20.
Selected to exert pressure on 0. In this exemplary embodiment of the invention, cover 510 has a cavity with a height of 42.83 mm, which cavity includes lower spring assembly 200, sphere 300, and
Housing upper spring assembly 420. As a result, in the opto-mechanical pedestal 500, the springs in the upper spring assembly 420 and the lower spring assembly 200 abut the sphere 300 and exert a force in its radial direction.

All the components of the opto-mechanical pedestal 500 are
It is formed of the same material or substantially similar materials or similar materials that have at least the same coefficient of thermal expansion (CTE). If the coefficients of thermal expansion are the same, the entire assembly will expand and contract all at once when subjected to temperature changes. This keeps the sphere 300 from rotating during exposure to temperature changes during the acclimation process, and preserves the angular alignment of the optics when temperature changes.

In the exemplary embodiment, upper spring assembly 420 is substantially identical to lower spring assembly 200, except that lower spring assembly 200 is attached to base plate 410 and upper spring assembly 420 is attached to cover 510. As shown in FIG. 6A, the springs 620-1 620-2, 620-3 (see FIG. 6A) of the upper spring assembly 420 are spherical.
Corresponding springs 220 along individual lines passing through the center of 300
-1, 220-2, 220-3 are oriented so as to directly face each other. For example, springs 220-1, 220-2, 220-3 (see FIG. 2)
Are located at 0 °, 240 °, 120 ° about the vertical axis of the sphere 300, while the springs 620-1, 620-2, 620-3 are 180 °, 60 ° about the vertical axis. , Is located at a position of 300 °.
With this configuration, the spring pairs (220-1, 620-1), (220-
2, 620-2), (220-3, 620-3) spring force vectors have a common axis and pass through the center of the sphere 300. This causes each spring 220 or 620 to pass through the center of the sphere 300 and produce a corresponding opposing spring 620 or 2 on the common axis.
Each has 20. Thus, changes in spring 620, e.g., caused by temperature changes, counteract and counteract corresponding changes in spring 220, so that springs 220 and 620 exert no torque on sphere 300 and sphere 300 is displaced. prevent.

FIG. 6B is a diagram showing a spring structure of another embodiment of the present invention. The embodiment of FIG. 6B has four springs 63.
It uses 1, 632, 641, 642. Two springs 63
1, 632 are located in the lower spring assembly (not shown) and the other two springs 641, 642 are located in the upper spring assembly (not shown). Each spring 631, 632, 641, 642
Is a leaf spring having a surface perpendicular to the normal to the surface of the sphere 300 at each contact point. The upper and lower spring assemblies are identical to each other, but the upper spring assembly is rotated by 90 ° with respect to the lower spring assembly, so that the contact points of the springs 631, 632, 633, 634 and the ball 300 are symmetrical. It becomes the top of the tetrahedron. The resulting spring force on the sphere 300 is directed radially towards the center of the sphere 300,
Holds the ball 300 without exerting a torque on 00. Other spring configurations likewise can be used without the application of torque.
300 may be retained, for example a single spring at the top of sphere 300 may be arranged to oppose and resist the resultant force of the three forces from spring 220. However, such an arrangement is shown in FIG. 6 in which each spring is paired with an opposing spring.
It lacks the symmetry of the A system. Therefore, thermal expansion of the pedestal utilizing the minimal restraint configuration as shown in FIG. 6B may change the position and orientation of the sphere 300.

Referring again to FIG. 5, the cover 510 includes a ball 3
There is an aperture 520 for the optical path to the optical elements in 00 and an aperture 530 for the tool utilized to rotate the sphere 300 during the alignment process that aligns the spheres. Further, because the spring assembly 420 is ring-shaped, an opening 540 in the top of the cover 500 or base plate 410 allows the optical path to pass through the top of the cover 510 and is used to rotate the sphere 300 during the alignment process. Allows access to the top of the sphere 300 for the tool being played. Sphere 3 through base plate 410 as well
Access to the bottom of 00 is also possible.

Although a wide variety of optical elements can be used in the sphere 300, the sphere 300 is generally used.
The center of is located on the optical surface, the axis and / or the plane of symmetry of the optical element within the sphere 300. For example, FIG. 7 shows a sphere 700 that includes a refractive relay optical element 710 for shifting the position of a laser beam perpendicular to the direction of laser beam propagation. The repeater 710 can be simply optical quality glass with parallel optical surfaces, or a thick member of optical glass. By inserting a hexagon wrench into the opening 720, the sphere 700 can be rotated in the opto-mechanical pedestal as described above, and the incident angle of the input beam can be changed to cause the deviation amount of refraction in the repeater 710. Can be controlled. Additional access ports for tools can be provided in almost any position, especially at 45 ° in the vertical plane.

8A and 8B are perspective views of a sphere 800 utilized in a beam bender. The sphere 800 has an opening into which an optical element 810 having a highly reflective surface 812 is inserted and attached. Aperture 820 is for the input beam entering sphere 800 and the reflected beam exiting sphere 800. Aperture 830 is accessible through an aperture in the cover of the opto-mechanical pedestal, but a lever can rotate sphere 800 when the input beam needs to be aligned and aligned with highly reflective surface 812. . Optical element 8
10 is positioned such that the highly reflective coating 812 is in the center of the sphere 800 and rotating the sphere 800 changes the angle of incidence of the input beam on the surface 812, but does not change the point of incidence on the surface 812. To be done.

FIG. 9A illustrates another embodiment of the present invention utilizing a spring washer 900. The ball 300 is positioned on the lower spring washer 910 so that the lower spring washer 910 abuts the ball 300 along the circumferential direction of the annular portion of the surface of the ball 300. The upper spring washer 920 is arranged opposite the lower spring washer 910, so that the upper spring washer 920 also abuts the ball 300 along the circumferential direction of the annular portion of the surface of the ball 300.

Spring washer 900 is preferably formed from a metal such as spring steel, stainless steel or carbon steel.
In some applications, the spring washer 900 can be polished to reduce surface friction during alignment and alignment of the sphere 300. The spring washer shown in the exemplary embodiment is a disc spring washer, a type of washer known in the art. Other washers, such as modified disc spring washers, can also be used.
The example embodiment spring washer 900 has an outer diameter of about 36 mm and 2
It has an inner diameter of 2.4 mm and a wall thickness of 0.1 to 0.3 mm.

FIG. 9B is assembled according to this embodiment of the invention (collectively assembly 930).
FIG. 9 is a cross-sectional view of a ball 300, a spring washer 900, and a support ring 940.
The lower support ring 950 and the upper support ring 960 are similar to the support ring 210 shown in FIG. Each support ring 940 is substantially ring-shaped, but its inner surface is cylindrical rather than conical, and features that retain the leaf spring 220 within the support ring 210.
Does not have 230. The spring washer 900 is positioned at the end of the cylindrical inner surface of the support ring 940. In an alternative embodiment, the inner surface of the support ring 940 is slightly angled and truncated conical to help hold the spring washer 900 in place. The spring washer 900 is fixed to the support ring 940 by a known method (for example, welding). Alternatively, the spring washer 900 can remain unfixed to the support ring 940.

In assembling the opto-mechanical cradle, the assembly 930 is attached to the base plate 410 (shown in FIG. 5). A cover 510 (shown in FIG. 5) is placed on the assembly 930 such that the cover 510 and base plate 410 exert a force on the support ring 940. Cover 510 and base plate
The gap with 410 can be varied so that the magnitude of the force exerted can be varied. The support ring 940 exerts a force on the spring washer 900, which causes the upper spring washer 920 to exert an equal force on the sphere 300 on a common axis opposite the force provided by the lower spring washer 910.

Although the present invention has been described with respect to particular embodiments, the embodiments described are merely illustrative of the invention and are not to be construed as limiting the invention. For example, although various specific dimensions and materials have been described with respect to exemplary embodiments of the invention, these dimensions and materials can be widely varied and replaced. Various other applications and combinations of the features of the disclosed embodiments are within the scope of the invention, which is defined by the content of the claims.

[0035]

INDUSTRIAL APPLICABILITY The present invention provides a sphere (30) for containing an optical element.
Opto-mechanical pedestal (50) including an upper spring assembly (420) and a lower spring assembly (200) that supports and secures (0).
0) concerning. The material of the cradle (500) has the same or similar coefficient of thermal expansion (CTE), and the spring assembly (2
00, 420) provide opposing radial forces so that the thermal expansion is offset and the cradle (500) has excellent thermal stability. The frictional force exerted on the sphere (300) from the upper spring assembly (420) and the lower spring assembly (200) maintains the orientation of the sphere (and of the optical element) during operation, but the sphere (300) and spring The smooth surface of (220, 620) is the sphere (3
00) without aligning or clamping after alignment
It still allows a sensitive and precise rotation of the sphere (300) to align. The spring assembly can be ring-shaped and can be used for optical paths or for tools that adjust the alignment of the spheres.
It provides an opening (540) towards the sphere through the spring assembly.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a known opto-mechanical pedestal.

FIG. 2 is a perspective view of a lower spring assembly for an opto-mechanical pedestal according to one embodiment of the present invention.

3 is a perspective view of a sphere including an optical element and located in the lower spring assembly of FIG. 2. FIG.

FIG. 4 is a perspective view of an upper spring assembly, a sphere containing optical elements, a lower spring assembly, and a base plate for an opto-mechanical pedestal according to one embodiment of the present invention.

FIG. 5 is a perspective view of a completed optomechanical pedestal according to an embodiment of the present invention.

6A and 6B are perspective views showing the relative orientations of support springs in an alternative embodiment of the present invention.

FIG. 7 is a view showing a sphere including a refracting relay optical element for a gantry according to an embodiment of the present invention.

8A and 8B are diagrams illustrating a sphere including a reflected beam bender / splitter for a cradle according to another embodiment of the present invention.

9A and 9B are views showing a sphere positioned between two spring washers in another embodiment of the present invention, and FIG. 9B is taken along the line BB ′ shown in FIG. 9A. 9B is a cross-sectional view of the object of FIG. 9A taken along a vertical plane, with the addition of a support ring, and the cross-section of the sphere shown as a circle for clarity and ease of understanding.

[Explanation of symbols]

12 spheres 14 Support 20 Spherical nesting 26 Spring preload plunger 28 Tightening screw 100 Optical mechanical mount 200 Lower Spring Assembly 210 Support ring 220 leaf spring 220-1, 220-2, 220-3 Spring 230 Creation 232 shelves 234 Stitch welding 240 Positioning pin 300 balls 310, 320, 330 openings 410 Base plate 420 Upper Spring Assembly 500 Optical mechanical mount 510 cover 520, 530 openings 620 spring 620-1, 620-2, 620-3 spring 631, 632, 641, 642 springs 700 balls 710 Refractive relay optical element 720 opening 800 balls 810 Optical element 812 High reflective surface 820,830 openings 900 spring washer 910 Lower spring washer 920 Upper spring washer 930 assembly 940 support ring 950 Lower support ring 960 Upper support ring

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenneth Jay Wayne             California 95070,             Saratoga, Park Drive 15111 (72) Inventor Jean W. Broenink             Netherlands 1383 AS Weeps, Be             Rice Polderweg 5 (72) Inventor Engelbertas Are F Van             De Pash             Dutch Country 5688 R.H. Oil Show             Toh Van Heester Beakstler             To 8 (72) Inventor Marcel H.M.Beams             Netherlands 5508 EK Feldhof             En, Ranselgelkwek 37 F-term (reference) 2H043 AB06 AB09 AB10 AB30 AB38                       BC06 BC07                 2H044 AA15 AH15

Claims (3)

[Claims] 1. A sphere (300) adapted to mount an optical element therein, and one or more springs (220,910) abutting the sphere.
A first spring group consisting of, and one or more springs (620, 920) contacting the sphere.
An opto-mechanical system comprising: 2. The spring of the first spring group is a spring washer (91).
0, 920). 3. An opto-mechanical system in which each spring of the first spring group and the second spring group comprises a spring washer (910, 920).