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Title: MULTIPLE FUNCTIONS LONG TRACE PROFILER (LTP-MF) FOR NATIONAL SYNCHROTRON RADIATION LABORATORY OF CHINA.

Abstract

The Long Trace Profiler (LTP) is a useful optical metrology instrument for measuring the figure and slope error of cylindrical aspheres commonly used as synchrotron radiation (SR) optics. It is used extensively at a number of synchrotron radiation laboratories around the world. In order to improve SR beam line quality and resolution, the National Synchrotron Radiation Laboratory (NSRL) of China is developing a versatile LTP that can be used to measure both SR optics and more conventional ''normal'' optical surfaces. The optical metrology laboratories at Brookhaven National Laboratory (BNL) and NSRL are collaborating in developing a multiple functions LTP (LTP-MF). Characteristics of the LTP-MF are: a very compact and lightweight optical head, a large angular test range ({+-} 16 mad) and high accuracy. The LTP-MF can be used in various configurations: as a laboratory-based LTP, an in-situ LTP or penta-prism LTP, as an angle monitor, a portable LTP, and a small radius of curvature test instrument. The schematic design of the compact optical head and a new compact slide are introduced. Analysis of different measurements modes and systematic error correction methods are introduced.

Authors:
; ; ;
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
DOE/SC
OSTI Identifier:
15020382
Report Number(s):
BNL-74916-2005-CP
R&D Project: IO-04; KC-02-04-011; TRN: US0504322
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Conference
Resource Relation:
Conference: OPTICS AND PHOTONICS CONFERENCE 2005; SAN DIEGO, CA; 20050731 through 20050804
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCURACY; DESIGN; OPTICS; RESOLUTION; SYNCHROTRON RADIATION

Citation Formats

QIAN, S., WANG, Q., HONG, Y., and TAKACS, P. MULTIPLE FUNCTIONS LONG TRACE PROFILER (LTP-MF) FOR NATIONAL SYNCHROTRON RADIATION LABORATORY OF CHINA.. United States: N. p., 2005. Web.
QIAN, S., WANG, Q., HONG, Y., & TAKACS, P. MULTIPLE FUNCTIONS LONG TRACE PROFILER (LTP-MF) FOR NATIONAL SYNCHROTRON RADIATION LABORATORY OF CHINA.. United States.
QIAN, S., WANG, Q., HONG, Y., and TAKACS, P. Sun . "MULTIPLE FUNCTIONS LONG TRACE PROFILER (LTP-MF) FOR NATIONAL SYNCHROTRON RADIATION LABORATORY OF CHINA.". United States. doi:. https://www.osti.gov/servlets/purl/15020382.
@article{osti_15020382,
title = {MULTIPLE FUNCTIONS LONG TRACE PROFILER (LTP-MF) FOR NATIONAL SYNCHROTRON RADIATION LABORATORY OF CHINA.},
author = {QIAN, S. and WANG, Q. and HONG, Y. and TAKACS, P.},
abstractNote = {The Long Trace Profiler (LTP) is a useful optical metrology instrument for measuring the figure and slope error of cylindrical aspheres commonly used as synchrotron radiation (SR) optics. It is used extensively at a number of synchrotron radiation laboratories around the world. In order to improve SR beam line quality and resolution, the National Synchrotron Radiation Laboratory (NSRL) of China is developing a versatile LTP that can be used to measure both SR optics and more conventional ''normal'' optical surfaces. The optical metrology laboratories at Brookhaven National Laboratory (BNL) and NSRL are collaborating in developing a multiple functions LTP (LTP-MF). Characteristics of the LTP-MF are: a very compact and lightweight optical head, a large angular test range ({+-} 16 mad) and high accuracy. The LTP-MF can be used in various configurations: as a laboratory-based LTP, an in-situ LTP or penta-prism LTP, as an angle monitor, a portable LTP, and a small radius of curvature test instrument. The schematic design of the compact optical head and a new compact slide are introduced. Analysis of different measurements modes and systematic error correction methods are introduced.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jul 31 00:00:00 EDT 2005},
month = {Sun Jul 31 00:00:00 EDT 2005}
}

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  • The Long Trace Profiler (LTP) is in use at several synchrotron radiation (SR) laboratories throughout the world and by a number of manufacturers who specialize in making grazing incidence mirrors for SR customers. Recent improvements in the design and operation of the LTP system have reduced the slope profile error bar to the level of 0.3 microradians RMS over measurement lengths of 0.5 meter. This corresponds to a height error bar on the order of 20 nanometers. This level of performance allows one to measure with confidence the shape of large cylinders and spheres that have kilometer radii of curvaturemore » in the axial direction. The LTP is versatile enough to make measurements of a mirror in the face up, sideways, and face down configurations. The authors will illustrate the versatility of the current version of the instrument, the LTP II, and present results from two new versions of the instrument: the in-situ LTP (ISLTP) and the Vertical Scan LTP (VSLTP). Both of them are based on the penta-prism LTP (ppLTP) principle with a stationary optical head and moving penta-prism. The ISLTP is designed to measure the distortion of high heat load mirrors during actual operation in SR beam lines. The VSLTP is designed to measure the complete 3-dimensional shape of x-ray telescope cylinder mirrors and mandrels in a vertical configuration. Scans are done both in the axial direction and in the azimuthal direction.« less
  • Metrology requirements for optical components for third generation synchrotron sources are taxing the state-of-the-art in manufacturing technology. We have investigated a number of effect sources in a commercial figure measurement instrument, the Long Trace Profiler II (LTP II), and have demonstrated that, with some simple modifications, we can significantly reduce the effect of error sources and improve the accuracy and reliability of the measurement. By keeping the optical head stationary and moving a penta prism along the translation stage, the stability of the optical system is greatly improved, and the remaining error signals can be corrected by a simple referencemore » beam subtraction. We illustrate the performance of the modified system by investigating the distortion produced by gravity on a typical synchrotron mirror and demonstrate the repeatability of the instrument despite relaxed tolerances on the translation stage.« less
  • Metrology requirements for optical components for third-generation synchrotron sources are taxing the state of the art in manufacturing technology. We have investigated a number of error sources in a commercial figure measurement instrument, the Long-Trace-Profiler II, and have demonstrated that, with some simple modifications, we can significantly reduce the effect of error sources and improve the accuracy and reliability of the measurement. By keeping the optical head stationary and moving a penta prism along the translation stage, as in the original pencil-beam interferometer design of von Bieren, the stability of the optical system is greatly improved, and the remaining errormore » signals can be corrected by a simple reference beam subtraction. We illustrate the performance of the modified system by investigating the distortion produced by gravity on a typical synchrotron mirror and demonstrate the repeatability of the instrument despite relaxed tolerances on the translation stage.« less
  • The Long Trace Profiler (LTP) is used primarily for measuring the figure of long synchrotron beamline mirrors. The LTP has also been used for measuring the figure of the substrate of beamline gratings. We propose a method for measuring the effective figure that comes from the gratings groove pattern on the substrate of long beamline gratings. Analysis of gratings groove patterns can be useful in determining cause of poor imaging of the diffracted light, but requires investigation of small changes of the groove frequency over the entire clear aperture of the grating. A diffraction grating that is small enough tomore » be measured by a general purpose six inch aperture interferometer is measured by both this interferometer and the LTP, so that results for two different instruments may be compared. The height profile of the substrate light (m = 0) measurement is subtracted from the height profile of the diffracted light (m = 1) measurement, and the result is the effect of only the diffraction f rom the grooves along the entire surface. This procedure is also used for a diffraction grating that is too long to be measured by the general purpose interferometer, but is easily measured by the LTP.« less
  • Long trace profilers (LTPS) have been used at many synchrotron radiation laboratories worldwide for over a decade to measure surface slope profiles of long grazing incidence x-ray mirrors. Phase measuring interferometers (PMIs) of the Fizeau type, on the other hand, are being used by most mirror manufacturers to accomplish the same task. However, large mirrors whose dimensions exceed the aperture of the Fizeau interferometer require measurements to be carried out at grazing incidence, and aspheric optics require the use of a null lens. While an LTP provides a direct measurement of ID slope profiles, PMIs measure area height profiles frommore » which the slope can be obtained by a differentiation algorithm. Measurements of the two types of instruments have been found by us to be in good agreement, but to our knowledge there is no published work directly comparing the two instruments. This paper documents that comparison. We measured two different nominally flat mirrors with both the LTP in operation at the Advanced Photon Source (a type-II LTP) and a Fizeau-type PMI interferometer (Wyko model 6000). One mirror was 500 mm long and made of Zerodur, and the other mirror was 350 mm long and made of silicon. Slope error results with these instruments agree within nearly 100% (3.11 {+-} 0.15 {micro}rad for the LTP, and 3.11 {+-} 0.02 {micro}rad for the Fizeau PMI interferometer) for the medium quality Zerodur mirror with 3 {micro}rad rms nominal slope error. A significant difference was observed with the much higher quality silicon mirror. For the Si mirror, slope error data is 0.39 {+-} 0.08 {micro}rad from LTP measurements but it is 0.35 {+-} 0.01 {micro}rad from PMI interferometer measurements. The standard deviations show that the Fizeau PMI interferometer has much better measurement repeatability.« less