摘要:
An improved technique for determining the thickness of a member, especially pipe such as fluid-filled casing in an earth borehole, includes the following steps: directing a pulse of ultrasonic energy toward the inner surface of the pipe, and receiving and storing, as a function of time, signals representative of ultrasonic energy reflected from the inner surface of the pipe; determining, from the stored signals, the arrival time of the initial echo from the inner surface; determining, from the stored signals, the arrival time and the amplitude of a first candidate initial echo from the outer surface of the pipe; performing a reverse search on the stored signals to determine, from stored signals at times earlier than the arrival time of the first candidate, the arrival time and the amplitude of a second candidate initial echo from the outer surface; comparing amplitudes of the first and second candidates, and selecting, based on the comparison, one of the first and second candidates as the actual outer surface echo; and determining the thickness of the pipe from the arrival time of the actual outer surface echo and the arrival time of the inner surface echo. Using this technique, the earlier arriving candidate can be properly identified as the actual outer surface echo, even when the later arriving candidate has a greater amplitude.
摘要:
An improved technique for determining the thickness of a member, especially pipe such as fluid-filled casing in an earth borehole, includes the following steps: directing a pulse of ultra-sonic energy toward the inner surface of the pipe and receiving/storing, as a function of time, signals representative of ultra-sonic energy reflected from the inner surface of the pipe; determining, from the stored signals, the arrival or the initial echo from the inner surface; determining from the stored signals, the arrival and the amplitude of a first candidate initial echo from the outer surface of the pipe; performing a reverse search on the stored signals to determine, from stored signals at times earlier than the arrival time of the first candidate the arrival and the amplitude of a second candidate initial echo from the outer surface; comparing amplitudes of the first and second candidates and selecting, based on the comparison, one of the first and second candidates as the actual outer surface echo; and determining the thickness of the pipe from the arrival time of the actual outer surface echo and the arrival time of the inner surface echo. Using this technique, the earlier arriving candidate can be properly identified as the actual outer surface echo, even when the later arriving candidate has a greater amplitude.
摘要:
An optical measurement system for evaluating a sample has a motor-driven rotating mechanism coupled to an azimuthally rotatable measurement head, allowing the optics to rotate with respect to the sample. A polarimetric scatterometer, having optics directing a polarized illumination beam at non-normal incidence onto a periodic structure on a sample, can measure optical properties of the periodic structure. An E-O modulator in the illumination path can modulate the polarization. The head optics collect light reflected from the periodic structure and feed that light to a spectrometer for measurement. A beamsplitter in the collection path can ensure both S and P polarization from the sample are separately measured. The measurement head can be mounted for rotation of the plane of incidence to different azimuthal directions relative to the periodic structures. The instrument can be integrated within a wafer process tool in which wafers may be provided at arbitrary orientation.
摘要:
This invention is an apparatus for imaging metrology, which in particular embodiments may be integrated with a processor station such that a metrology station is apart from but coupled to a process station. The metrology station is provided with a first imaging camera with a first field of view containing the measurement region. Alternate embodiments include a second imaging camera with a second field of view. Preferred embodiments comprise a broadband ultraviolet light source, although other embodiments may have a visible or near infrared light source of broad or narrow optical bandwidth. Embodiments including a broad bandwidth source typically include a spectrograph, or an imaging spectrograph. Particular embodiments may include curved, reflective optics or a measurement region wetted by a liquid. In a typical embodiment, the metrology station and the measurement region are configured to have 4 degrees of freedom of movement relative to each other.
摘要:
This invention is an apparatus for imaging metrology, which in particular embodiments may be integrated with a processor station such that a metrology station is apart from but coupled to a process station. The metrology station is provided with a first imaging camera with a first field of view containing the measurement region. Alternate embodiments include a second imaging camera with a second field of view. Preferred embodiments comprise a broadband ultraviolet light source, although other embodiments may have a visible or near infrared light source of broad or narrow optical bandwidth. Embodiments including a broad bandwidth source typically include a spectrograph, or an imaging spectrograph. Particular embodiments may include curved, reflective optics or a measurement region wetted by a liquid. In a typical embodiment, the metrology station and the measurement region are configured to have 4 degrees of freedom of movement relative to each other.
摘要:
A database interpolation method is used to rapidly calculate a predicted optical response characteristic of a diffractive microstructure as part of a real-time optical measurement process. The interpolated optical response is a continuous and (in a preferred embodiment) smooth function of measurement parameters, and it matches the theoretically-calculated optical response at the database-stored interpolation points.
摘要:
A spectroscopic ellipsometer having a multiwavelength light source, spectrometer (or wavelength-scanning monochromator and photodetector), a polarizer and polarization analyzer, and one or more objectives in the illumination and collection light paths, further comprises a stationary polarization modulator that modulates the light polarization versus wavelength. Modulator can be an optically active crystal rotating the linear polarization plane by a different angle for each wavelength or a non-achromatic waveplate retarder that varies the relative phase delay of the polarization components periodically over wavelength. The measured spectrum can be used to characterize selected features or parameters of a sample, e.g. by comparison with one or more theoretical spectra.
摘要:
A method and apparatus for spatially filtering a signal set to enhance interface echoes representing a borehole configuration. The spatial filtering technique provides information regarding the various interfaces formed between materials in the borehole environment, as well as thicknesses of the various materials present in the borehole. Further, the presence of channels formed during the cementing procedure are detected.
摘要:
A database interpolation method is used to rapidly calculate a predicted optical response characteristic of a diffractive microstructure as part of a real-time optical measurement process. The interpolated optical response is a continuous and (in a preferred embodiment) smooth function of measurement parameters, and it matches the theoretically-calculated optical response at the database-stored interpolation points.
摘要:
The invention is a method and apparatus for determining characteristics of a sample. The system and method provide for detecting a monitor beam reflected off a mirror, where the monitor beam corresponds to the intensity of light incident upon the sample. The system and method also provide for detecting a measurement beam, where the measurement beam has been reflected off the sample being characterized. Both the monitor beam and the measurement beam are transmitted through the same transmission path, and detected by the same detector. Thus, potential sources of variations between the monitor beam and the measurement beam which are not due to the characteristics of the sample are minimized. Reflectivity information for the sample can be determined by comparing data corresponding to the measurement beam relative to data corresponding the monitor beam.