High precision measurement of gyro rotor sphericity

Lipa, J. A.; Siddall, G.J.

doi:10.1016/0141-6359(80)90026-4

Cited by 24 publications

(12 citation statements)

References 5 publications

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“…These were lapped and polished at Stanford, yielding <20 nm peak deviation of the rotor surface from the best fit sphere [10,11]. Rotor asphericity was measured using a Talyrond Model 73 roundness measuring instrument [12], manufactured by the Rank Taylor Hobson Company, shown in figure 3. Stereoscopic projections of the deviations from a best fit sphere were developed for visualizing the topography of a given rotor [13,14].…”

Section: Gyroscope Overviewmentioning

confidence: 99%

The Gravity Probe B gyroscope

Buchman¹,

Lipa²,

Muhlfelder³

et al. 2015

Class. Quantum Grav.

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The Gravity Probe B (GP-B) gyroscope, a unique cryogenically operated mechanical sensor, was used on-orbit to independently test two predictions of general relativity (GR). Here, we describe the development and performance of the GP-B gyroscope, its geometry and fabrication, spin-up and vacuum approach, magnetic considerations, and static charge management. The history of electrically suspended gyroscopes puts the current work in context. Fabrication and ground testing of the GP-B gyroscope are detailed, followed by a review of on-orbit initialization, calibration, operation, and performance. We find that the performance was degraded relative to the mission goals, but was still sufficient to provide excellent new tests of GR. The degradation is partially due to the existence of gyroscope torques due to an unanticipated interaction between patch potentials on the rotor and the housing. We discuss these patch potentials and describe the effect of related torques on gyro drift. It was essential to include models for the effects due to the patch potentials in the complete data analysis model to yield determinations of the two GR effects.

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Section: Gyroscope Overviewmentioning

confidence: 99%

The Gravity Probe B gyroscope

Buchman¹,

Lipa²,

Muhlfelder³

et al. 2015

Class. Quantum Grav.

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“…Also, it has potential to damage the surface due to the mechanical contact between the probe and the component. The same drawbacks also exist in roundness measuring instrument 9 , 10 . Technologies like fluorescent stereo microscopy 11 and stereo cameras 12 are able to characterize the bilateral profiles of curved transparent components and their thickness distribution.…”

Section: Introductionmentioning

confidence: 99%

“…The same drawbacks also exist in roundness measuring instrument. 9,10 Technologies like fluorescent stereo microscopy 11 and stereo cameras 12 are able to characterize the bilateral profiles of curved transparent components and their thickness distribution. Nevertheless, they impose severe restrictions on the measurement environment and have relatively low measurement accuracy.…”

Section: Introductionmentioning

confidence: 99%

Bilateral form characterization of curved transparent components using chromatic confocal sensor

Wu,

Zhao,

Jiang

et al. 2023

Opt. Eng.

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To accurately characterize the geometric form of key components in industrial products, many profile measuring instruments have been developed to date. However, there are some special components, such as the hemispherical resonators featuring thin curved transparent surfaces, which are difficult to be measured using general instruments. The chromatic confocal technology was introduced in this paper to conduct the bilateral form characterization of this type of surfaces. Based on the assumption of tilted plate approximation, a modified ray tracing model was presented to correct the errors produced by the curved surfaces. The experiment of measurement on tilted, fused silica plates was conducted to demonstrate the effectiveness of the proposed model. Results show that the developed model improves the measurement accuracy of plates with large tilt angle. A three-axis motion stage was built with self-developed chromatic confocal sensor to obtain the bilateral profiles of the resonator. By fitting the spheres with the scanning profiles, the form error between the measurement points and the fitted spheres can be calculated. Partial form errors along the circumferential and axial directions of the resonator are evaluated, and an intuitive assessment of its thickness variation along the circumferential direction was made.

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“…It can find many applications in precision components and instruments, such as gyrorotors [1,2], precision ball bearings [3,4], and calibration spheres [5,6]. The figure error or the sphericity of the whole surface is vital for the instruments to achieve high performance.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, a hyperhemisphere can be inspected with high-precision roundness measurement [1][2][3]. By using an air-bearing spindle and the spindle error separation technique, the roundness measuring instrument can achieve ultrahigh-precision measurement of roundness.…”

Section: Introductionmentioning

confidence: 99%

Self-calibrated subaperture stitching test of hyper-hemispheres using latitude and longitude coordinates

et al. 2012

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Limited by the f-number of the transmission sphere, it is impossible to test the whole surface of a hyper-hemisphere using a standard interferometer directly. This paper presents an extension of the subaperture stitching test method to hyper hemispheres. The stitching algorithm is based on the coordinate mapping from local measurement frame to a global frame, and overlapping correspondence is calculated by virtue of coordinates of latitude and longitude. The reference surface error is represented by Zernike polynomials and self-calibrated during the stitching to achieve higher accuracy. Then the stitched surface error distribution is presented by map projection. To realize accessibility to the whole surface of a hyper-hemisphere, we also propose a design for the subaperture test platform, according to the subaperture lattice design. Finally, a hemisphere and a full sphere are tested and figured, respectively, to validate the method and the experimental setup.

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High precision measurement of gyro rotor sphericity

Cited by 24 publications

References 5 publications

The Gravity Probe B gyroscope

The Gravity Probe B gyroscope

Bilateral form characterization of curved transparent components using chromatic confocal sensor

Self-calibrated subaperture stitching test of hyper-hemispheres using latitude and longitude coordinates

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