Research Interests:
Design work carried out as part of the pre-phase A studies in support of an orbiting COLUMBUS spectroscopy observatory is summarized. Also included are new findings resulting from a reanalysis initiated in response to the following... more
Design work carried out as part of the pre-phase A studies in support of an orbiting COLUMBUS spectroscopy observatory is summarized. Also included are new findings resulting from a reanalysis initiated in response to the following guidelines: (1) The strawman satellite design, which assumed a telescope 6 meters in length followed by a 3-meter spectrograph, resulted in an observatory which
Research Interests:
High resolution M/sub 4,5/ (3d ..-->.. 4p) x-ray emission spectra from a krypton plasma were measured using a recently developed grazing-incidence reflection-grating monochromator/spectrometer with very high flux rates at extreme... more
High resolution M/sub 4,5/ (3d ..-->.. 4p) x-ray emission spectra from a krypton plasma were measured using a recently developed grazing-incidence reflection-grating monochromator/spectrometer with very high flux rates at extreme ultraviolet and soft x-ray wave lengths. The nominal resolving power of the instrument, E/..delta..E, is about 300 in this energy range (approx.80 eV). Three dipole-allowed 3d ..-->.. 4p emission lines were observed at 80.98 eV, 80.35 eV and 79.73 eV. A broad peak at about 82.3 eV is tentatively assigned to transitions resulting from Kr/sup 2 +/, and effects of excitation energy on M/sub 4,5/ x-ray emission were observed. 9 refs., 3 figs., 1 tab.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Grazing incidence reflection grating design options for faint X-ray source spaceborne observation are considered. Geometries based on objective gratings and convergent beam varied line-space gratings are discussed. In-plane (classical)... more
Grazing incidence reflection grating design options for faint X-ray source spaceborne observation are considered. Geometries based on objective gratings and convergent beam varied line-space gratings are discussed. In-plane (classical) and off-plane (conical) grating mountings are compared.
Research Interests:
Research Interests:
Spectroscopic analysis is a powerful technique for the diagnosis of temperatures and compositions of astrophysical plasmas. The EUV (100–1000Å) and soft x-ray (10–100Å) bands contain hundreds of potentially useful diagnostic lines.... more
Spectroscopic analysis is a powerful technique for the diagnosis of temperatures and compositions of astrophysical plasmas. The EUV (100–1000Å) and soft x-ray (10–100Å) bands contain hundreds of potentially useful diagnostic lines. Unfortunately, traditional types of grating spectrometer become inefficient or unwieldy when adapted to stellar spectroscopy onboard a spacecraft. At grazing incidence, the required length of a high-resolution plane-grating spectrometer can easily exceed the length of the telescope feeding it. For these reasons, we have systematically explored ways to introduce a reflection grating into the converging beam formed by a given objective optical system ahead of its first focus. A spectrometer of this type results in an optical train no longer than the telescope’s existing prime-focus beam.
Research Interests:
A new geometric scheme translates a diffraction grating along the straight central groove of an exponentially curved pattern. Lit by a stationary incident beam, the two-dimensional pattern scales isotropically, scanning wavelength without... more
A new geometric scheme translates a diffraction grating along the straight central groove of an exponentially curved pattern. Lit by a stationary incident beam, the two-dimensional pattern scales isotropically, scanning wavelength without change to any angles, macroscopic distances, curvatures or aberrations. This is exemplified by a new class of self-focused grating monochromator, analyzed by rigorous light-path expansion and numerical raytracing. All spectral aberrations in pure meridional powers (including defocus, coma and spherical aberration) cancel for any choice of angular deviation, magnification and translation range. The residual mixed powers yield Δλ/λ = 10<sup>-3</sup> ~ 10<sup>-5</sup> in the soft x-ray for plane and concave gratings at grazing incidence. Over the visible spectrum, Δλ/λ ~ 10<sup>-4</sup>is shown for plane gratings mounted at Littrow and at normal incidence in reflection or transmission.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
High resolution M/sub 4,5/ (3d ..-->.. 4p) x-ray emission spectra from a krypton plasma were measured using a recently developed grazing-incidence reflection-grating monochromator/spectrometer with very high flux rates at extreme... more
High resolution M/sub 4,5/ (3d ..-->.. 4p) x-ray emission spectra from a krypton plasma were measured using a recently developed grazing-incidence reflection-grating monochromator/spectrometer with very high flux rates at extreme ultraviolet and soft x-ray wave lengths. The nominal resolving power of the instrument, E/..delta..E, is about 300 in this energy range (approx.80 eV). Three dipole-allowed 3d ..-->.. 4p emission lines were observed at 80.98 eV, 80.35 eV and 79.73 eV. A broad peak at about 82.3 eV is tentatively assigned to transitions resulting from Kr/sup 2 +/, and effects of excitation energy on M/sub 4,5/ x-ray emission were observed. 9 refs., 3 figs., 1 tab.
Research Interests:
We have mapped CO emission over a 5° x 5° area in the Cains Major OB1/R1 region. Most of the emission is confied to an elliptical region of approximately 90 x 60 pc. Several CO emission peaks appear, many associated with reflection... more
We have mapped CO emission over a 5° x 5° area in the Cains Major OB1/R1 region. Most of the emission is confied to an elliptical region of approximately 90 x 60 pc. Several CO emission peaks appear, many associated with reflection nebulae. While most of the emission falls in the LSR velocity range 10--20 km sâ»Â¹, we find some material over the full velocity covered (-30 to +45 km sâ»Â¹). There is no simple pattern that would indicate a single expanding shell, but the observations are consistent with the idea that some energetic process, which took place in an initially inhomogeneous cloudy medium, was responsible for the observed morphology of the region. Simple arguments suggest that a supernova explosion is the most likely candidate for this energetic process. The relationship between the process that shaped the clouds and star formation in the region is discussed.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
We present a spectrometer design candidate for the X-ray Multi-Mirror (XMM) observatory, being planned by the European Space Agency (ESA) as a long-lived large-area array of tele scopes. The science requirement of moderate resolution... more
We present a spectrometer design candidate for the X-ray Multi-Mirror (XMM) observatory, being planned by the European Space Agency (ESA) as a long-lived large-area array of tele scopes. The science requirement of moderate resolution (E/AE ^ 100) spectroscopy in a two octave region (0.5-2 KeV) with extremely high throughput (effective area > 500 cm2) results in the use of grazing incidence reflection gratings. Due to the low image quality of the telescopes (^ 1 minute of arc), the grating dispersion must be maximized by use of the classical grating mount in which the spectrum is dispersed within the plane of incident radiation. Due to the small field of view afforded by the x-ray telescopes, the gratings must be situated in the converging beam at the exit of the telescope. A spectrometer module consists of a thin-foil conical mirror telescope, a stack of plane varied-space reflection gratings and an imaging proportional counter. This system is analyzed on the basis of dispersion...
Research Interests:
Research Interests:
A new geometric scheme translates a diffraction grating along the straight central groove of an exponentially curved pattern. Lit by a stationary incident beam, the two-dimensional pattern scales isotropically, scanning wavelength without... more
A new geometric scheme translates a diffraction grating along the straight central groove of an exponentially curved pattern. Lit by a stationary incident beam, the two-dimensional pattern scales isotropically, scanning wavelength without change to any angles, macroscopic distances, curvatures or aberrations. This is exemplified by a new class of self-focused grating monochromator, analyzed by rigorous light-path expansion and numerical raytracing. All spectral aberrations in pure meridional powers (including defocus, coma and spherical aberration) cancel for any angular deviation, magnification and translation range. The residual mixed powers yield Δλ/λ = 〖10〗^(-3) ~ 〖10〗^(-5) in the soft x-ray for plane and concave gratings at grazing incidence. Over the visible spectrum, Δλ/λ ~ 〖10〗^(-4) is shown for plane gratings mounted at Littrow and at normal incidence in reflection or transmission.
Research Interests:
Concerted rotations of a self-focused varied line-space diffraction grating about its groove axis and surface normal define a new geometric class of monochromator. Defocusing is canceled, while the scanned wavelength is reinforced at... more
Concerted rotations of a self-focused varied line-space diffraction grating about its groove axis and surface normal define a new geometric class of monochromator. Defocusing is canceled, while the scanned wavelength is reinforced at fixed conjugate distances and horizontal deviation angle. This enables high spectral resolution over a wide band, and is of particular advantage at grazing reflection angles. A new, rigorous light-path formulation employs non-paraxial reference points to isolate the lateral ray aberrations, with those of power-sum ď 3 explicitly expanded for a plane grating. Each of these 14 Fermat equations agrees precisely with the value extracted from numerical raytrace simulations. An example soft X-ray design (6 ˝ deviation angle and 2 ˆ 4 mrad aperture) attains a resolving power ą 25, 000 over a three octave scan range. The proposed rotation scheme is not limited to plane surfaces or monochromators, providing a new degree of freedom in optical design. Grating rotation about its third (meridional) axis may be employed to cancel vertical deflection of the diffracted beam while maintaining the above aberration correction. This enables a simpler (pure rotary) motion for the exit slit and a fixed beam direction both horizontally and vertically.
The author made three errors in a recent publication [M.C. Hettrick, “A Single-Element Plane Grating Monochromator”, Photonics 3(1), no. 3, 1-44 (2016)] and regrets any misunderstanding they may have caused. To maintain the rigor of the... more
The author made three errors in a recent publication [M.C. Hettrick, “A Single-Element Plane Grating Monochromator”, Photonics 3(1), no. 3, 1-44 (2016)] and regrets any misunderstanding they may have caused. To maintain the rigor of the new light-path expansion method introduced therein, the author herein provides the necessary corrections and explanations.
Research Interests:
Research Interests:
Research Interests:
A varied-space grating mounted to both rotate and translate constitutes a practical single element fixed slit monochromator which is in focus at all wavelengths. Monochromators, diffraction gratings, grazing incidence, x-ray optics.
Research Interests:
Research Interests:
Research Interests: Mechanical Engineering, Optics, Medical Imaging, Fiber Optics, Telecommunications, and 13 moreImaging, Photonics, Society, Optical, Light, Ray Tracing, Applied Optics, Optical physics, Spatial Variation, Extreme Ultraviolet, Electrical And Electronic Engineering, Diffraction Grating, and Spectral Resolution
Page 1. Extreme Ultraviolet Explorer spectrometer Michael C. Hettrick, Stuart Bowyer, Roger F. Malina, Christopher Martin, and Stanley Mrowka The design and calculated performance is described for a spectrometer included ...
Research Interests:
Attention is given to a spectrometer design candidate for the X-ray Multi-Mirror observatory, being planned by the European Space Agency as a long-lived large-area array of telescopes. The science requirement of moderate resolution... more
Attention is given to a spectrometer design candidate for the X-ray Multi-Mirror observatory, being planned by the European Space Agency as a long-lived large-area array of telescopes. The science requirement of moderate resolution spectroscopy in a two octave region with extremely high throughput leads to the use of grazing incidence reflection gratings. It is noted that the sensitivity of the
Research Interests:
A classically ruled diffraction grating consists of grooves which are equidistant, straight and parallel. Conversely the so-called "holographic" grating (formed by the interfering waves of coherent visible light) , although severely... more
A classically ruled diffraction grating consists of grooves which are equidistant, straight and parallel. Conversely the so-called "holographic" grating (formed by the interfering waves of coherent visible light) , although severely constrained by the recording wavelength and recording geometry, has grooves which are typically neither equidistant, straight nor parallel. In contrast a varied line-space (VLS) grating, in common nomenclature, is a design in which the groove positions are relatively unconstrained yet possess sufficient symmetry to permit mechanical ruling. Such seemingly exotic gratings are no longer only a theoretical curiosity, but have been ruled and used in a wide variety of applications. These include 1) aberration-corrected normal incidence concave gratings for Seya-Namioka monochromators and optical de-multiplexers, 2) flat-field grazing incidence concave gratings for plasma diagnostics, 3) aberration-corrected grazing incidence plane gratings for space-borne spectrometers, 4) focusing grazing incidence plane grating for synchrotron radiation monochromators, and 5) wavefront generators for visible interferometry of optical surfaces (particularly aspheres). Future prospects of VLS gratings as dispersing elements, wavefront correctors and beamsplitters appear promising. I discuss the history of VLS gratings, their present applications and their potential in the future.
Research Interests:
Page 1. RAPID COMMUNICATIONS This section was established to reduce the lead time for the publication of Letters containing new, significant material in rapid ly advancing areas of optics judged compelling in their timeliness. ...
Research Interests: Mechanical Engineering, Optics, Plasma Physics, Medical Imaging, Fiber Optics, and 14 moreTelecommunications, Photonics, Society, Electromagnetic Radiation, Ultraviolet, Optical, Light, Applied Optics, Optical physics, High Resolution, Ultraviolet Radiation, Extreme Ultraviolet, Electrical And Electronic Engineering, and Performance Test
Varied-space grazing incidence gratings in high resolution scanning spectrometers. [AIP Conference Proceedings 147, 237 (1986)]. Michael C. Hettrick, James H. Underwood. Abstract. We discuss the dominant geometrical aberrations ...
Research Interests:
Page 1. RAPID COMMUNICATIONS This section was established to reduce the lead time for the publication of Letters containing new, significant material in rapid-ly advancing areas of optics judged compelling in their timeliness. ...
Research Interests: Mechanical Engineering, Plasma Physics, Laser produced plasma, Electromagnetic Radiation, Applied Optics, and 9 moreOptical physics, Very high throughput, Soft X Ray, Ionizing Radiation, Electrical And Electronic Engineering, Spectral Resolution, Plasma Diagnostic, Performance Test, and Lawrence Berkeley Laboratory
... 138, 237 (1985). P. Kirkpatrick and AV Baez, "Formation of Optical Images by X-rays," J. Opt. ... (American Chemical Society, Washington, DC, 1983), p. 253. A. Franks, B. Gale, K. Lindsey, DJ Pugh, CJ Robbie, and M. Stedman,... more
... 138, 237 (1985). P. Kirkpatrick and AV Baez, "Formation of Optical Images by X-rays," J. Opt. ... (American Chemical Society, Washington, DC, 1983), p. 253. A. Franks, B. Gale, K. Lindsey, DJ Pugh, CJ Robbie, and M. Stedman, "Optical Components for X-ray Microscopy," Ann. ...
Research Interests:
Quantitative estimates are provided of the imaging performance expected from a varied line-space echelle spectrometer.
Research Interests:
ABSTRACT Recent work in the design of soft X-ray and extreme UV spectrographs has identified a new class of reflection gratings whose aberrations do not increase at grazing incidence. To achieve this characteristic, the groove spacings... more
ABSTRACT Recent work in the design of soft X-ray and extreme UV spectrographs has identified a new class of reflection gratings whose aberrations do not increase at grazing incidence. To achieve this characteristic, the groove spacings are varied in a continuous manner across a plano grating aperture. Ray traces of the concentric groove grating, the oriental fan grating and variations illustrate their potential for space astronomy and laboratory applications in the wavelength range of approximately λλ10-1000 Å. Both straight-groove and concentric-groove patterns have been successfully fabricated with varied line spacings through mechanical ruling techniques. A concave varied line-space grating has been measured to achieve 70% of its theoretical efficiency in the extreme UV. An interferometric method of fabrication is also discussed, in which the recording wavelength is scaled-up into the far UV or even visible region of the spectrum. This holographic grating is designated &quot;Type V.&quot; Two interferometers capable of recording grating wavefront aberrations in the extreme UV and soft X-ray are proposed.
Michael C. Hettrick and Stuart Bowyer University of California, Space Sciences Laboratory, Berkeley, California 94720. Received 16 August 1984. Sponsored by WR Hunter, Naval Research Laboratory. 0003-6935/84/213732-04 $02.00/0.© 1984... more
Michael C. Hettrick and Stuart Bowyer University of California, Space Sciences Laboratory, Berkeley, California 94720. Received 16 August 1984. Sponsored by WR Hunter, Naval Research Laboratory. 0003-6935/84/213732-04 $02.00/0.© 1984 Optical Society of ...
Research Interests:
Research Interests:
ABSTRACT © 1985 Optical Society of America
Research Interests:
Reflectance measurements were made of several metals illuminated from various angles with light at 14 wavelengths in the interval 46.5-283 A. The metals, Rh, Os, Pt and Au were deposited as 125 A films on a binding substrate through... more
Reflectance measurements were made of several metals illuminated from various angles with light at 14 wavelengths in the interval 46.5-283 A. The metals, Rh, Os, Pt and Au were deposited as 125 A films on a binding substrate through electron beam epitaxy. Measurements were made with a grazing incidence monochromator and a reflectometer. The data generally showed lowered reflectance with increasing angles of illumination and shorter wavelengths. The reflectance peak, however, was located at wavelengths of 100-160 A, particularly at large grazing incidences. The wavelengths correspond with the 5p to epsilon-d transition in all of the elements. Rh displayed the highest overall reflectance, and both Rh and Os were more efficient than Au or Pt.
Research Interests:
Research Interests:
... Troy W. Barbee is with Stanford University, Materials Science & Engineering, Stanford, California 94305 ... listed in Table I. Near normal incidence reflectivities were measured at wavelengths of 170.4 A (72.8 eV), 160.1 A (77.4... more
... Troy W. Barbee is with Stanford University, Materials Science & Engineering, Stanford, California 94305 ... listed in Table I. Near normal incidence reflectivities were measured at wavelengths of 170.4 A (72.8 eV), 160.1 A (77.4 eV), and 228 A (54.4 eV) produced by a Finley source ...
Research Interests:
Maximizing the quantum efficiency of microchannel plate detectors: The collection of photoelectrons from the interchannel web using an electric field. [Review of Scientific Instruments 54, 171 (1983)]. Richard Cordia Taylor, Michael C.... more
Maximizing the quantum efficiency of microchannel plate detectors: The collection of photoelectrons from the interchannel web using an electric field. [Review of Scientific Instruments 54, 171 (1983)]. Richard Cordia Taylor, Michael C. Hettrick, Roger F. Malina. Abstract. ...
Research Interests: Engineering, Scientific Instruments, Computer Simulation, Electromagnetic Radiation, Scientific, and 10 morePhysical sciences, Quantum Efficiency, CHEMICAL SCIENCES, Mathematical Model, Spatial resolution, Ultraviolet Radiation, Experimental Data, Electric Field, Extreme Ultraviolet, and Elementary Particles
This patent describes a spectrometer optical system employed in combination with a source of electromagnetic radiation and reception means. It comprises: a first concave mirror receiving electromagnetic radiation from the source and... more
This patent describes a spectrometer optical system employed in combination with a source of electromagnetic radiation and reception means. It comprises: a first concave mirror receiving electromagnetic radiation from the source and reflecting the electromagnetic radiation within a first plane; a second concave mirror receiving the electromagnetic radiation reflected from the source and reflecting the electromagnetic radiation to converge in a second plane. The first and second planes being substantially orthogonal relative to each other; a diffraction grating receiving the converging electromagnetic radiation from the source and producing a spectrum for capture by the reception means; and means for rotating the diffraction grating about an axis relative to the diffraction grating.
Research Interests:
An optical system and method comprising a diffraction grating which rotates about its surface normal to change the magnitude of the wavelength diffracted to an image location. At grazing incidence, such a rotation is determined to... more
An optical system and method comprising a diffraction grating which rotates about its surface normal to change the magnitude of the wavelength diffracted to an image location. At grazing incidence, such a rotation is determined to maintain the diffracted image in focus over a wide range in scanned wavelength. Monochromator and spectrometer embodiments include plane and curved surface gratings with both classical and varied-spaced groove patterns, and a variety of illumination geometries. In the simplest case, a grazing incidence monochromator is constructed in which a self-focusing classical spherical grating scans the value in wavelength which is transmitted between fixed slits located on the Rowland circle of the grating. The diffracted image remains in perfect focus over two octaves in wavelength at high efficiency, with both entrance and exit slits fixed in position, and the radiation aperture is constant.