Iridium-coated micropore x-ray optics using dry etching of a silicon wafer and atomic layer deposition

Ogawa, Tomohiro; Ezoe, Yuichiro; Moriyama, Teppei; Mitsuishi, Ikuyuki; Kakiuchi, Takuya; Ohashi, T.; Mitsuda, Kazuhisa; Putkonen, Matti

doi:10.1364/ao.52.005949

Cited by 18 publications

(15 citation statements)

References 14 publications

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“…We tested Ir ALD in the early stage of our development. 37 Although the coating was successful in terms of x-ray reflectivity, the cost was higher.…”

Section: Effective Areamentioning

confidence: 99%

Ultralightweight x-ray telescope missions: ORBIS and GEO-X

Ezoe

Miyoshi

Kasahara

et al. 2018

J. Astron. Telesc. Instrum. Syst.

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Toward an era of x-ray astronomy, next-generation x-ray optics are indispensable. To meet a demand for telescopes lighter than the foil optics but with a better angular resolution <1 arcmin, we are developing micropore x-ray optics based on micromaching technologies. Using sidewalls of micropores through a thin silicon wafer, this type can be the lightest x-ray telescope ever achieved. Two Japanese missions, ORBIS and GEO-X, will carry this telescope. ORBIS is a small x-ray astronomy mission to monitor supermassive blackholes, while GEO-X is a small exploration mission of the Earth's magnetosphere. Both missions need an ultralightweight (<1 kg) telescope with moderately good angular resolution (<10 arcmin) at an extremely short focal length (<30 cm). We plan to demonstrate this type of telescope in these two missions around 2020. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…We tested Ir ALD in the early stage of our development. 37 Although the coating was successful in terms of x-ray reflectivity, the cost was higher.…”

Section: Effective Areamentioning

confidence: 99%

Ultralightweight x-ray telescope missions: ORBIS and GEO-X

Ezoe

Miyoshi

Kasahara

et al. 2018

J. Astron. Telesc. Instrum. Syst.

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“…36 We have tested Ir ALD in the early stage of our development. 37 Although the coating was successful in terms of X-ray reflectivity, the cost was higher. The Pt ALD process consists of two reactions.…”

Section: Effective Areamentioning

confidence: 99%

Small satellites with MEMS x-ray telescopes for x-ray astronomy and solar system exploration

Ezoe

Miyoshi

Kasahara

et al. 2018

Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

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Toward a new era of X-ray astronomy, next generation X-ray optics are indispensable. To meet a demand for telescopes lighter than the foil optics but with a better angular resolution less than 1 arcmin, we are developing micropore X-ray optics based on micromaching technologies. Using sidewalls of micropores through a thin silicon wafer, this type can be the lightest X-ray telescope ever achieved. Two new Japanese missions ORBIS and GEO-X will carry this optics. ORBIS is a small X-ray astronomy mission to monitor supermassive blackholes, while GEO-X is a small exploration mission of the Earth's magnetosphere. Both missions need a ultra light-weight (<1 kg) telescope with moderately good angular resolution (<10 arcmin) at an extremely short focal length (<30 cm). We plan to demonstrate this optics in these two missions around 2020, aiming at future other astronomy and exploration missions.

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“…We coated the optic with Ir using a Beneq TFS 200 R&D ALD deposition tool with (ethylcyclopentadienyl) (1,5-cyclooctadiene) iridium, Ir (EtCp) (cod), and O 2 as precursors at 300 • C deposition temperature as described in Ogawa et al (2013). The Ir film thickness is 20 nm.…”

Section: Fabricationmentioning

confidence: 99%

“…When we consider the incorrect focal length and the angular error Table 6 Summary of raytracing simulations at 1.49 keV a The same h and σ rms are assumed for the first-and second-stage optics from the HPD values, the effective area increases to 110 mm 2 , which is larger than the ideal case because reflection angles can be smaller than the ideal case. Even when we consider the ridge structure that can geometrically shadow a part of incident photons as demonstrated in Ogawa et al (2013), the effective area is still 95 mm 2 . By adding the factor of the rms surface roughness on mirrors from the AFM measurement, the effective area is still 55 mm 2 .…”

Section: Effective Areamentioning

confidence: 99%

First X-ray imaging with a micromachined Wolter type-I telescope

et al. 2016

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be a new probe to investigate chemical compositions of planetary atmospheres, surfaces of planets, moons or asteroids and high energy particles in planetary magnetospheres. A potential future Japanese exploration to Jupiter needs a light-weight (<10 kg) X-ray imager in order to capture X-ray auroras from Jupiter . However, limited resources, i.e., mass, power, size, have hindered exploration satellites from carrying a good angular resolution and large effective area X-ray telescope.Wolter type-I telescopes have been widely used in X-ray astronomy. X-rays are doubly reflected upon paraboloid and hyperboloid mirrors, to minimize aberrations (Wolter 1952). A few to hundreds of mirrors are conically nested to increase the effective area. Each mirror is fabricated individually with either polishing of thick mirror substrates, replication of precisely fabricated mandrels, or thermal forming of thin aluminum foils. However, these mirrors have to be heavy when a high angular resolution is sought for Bavdaz et al. (2004). Furthermore, the lightest aluminum foil mirror approximates ideal mirror surfaces with cones, which degrades the angular resolution to 10 arcmin under a short focal length less than 1 m. Therefore, a new mirror fabrication technology is needed for future X-ray astronomy missions as well as planetary explorations.A possible solution is micropore optics (Frazer 1997). Sidewalls of micro pores whose width is typically of the order of 10 to 100 µm are used for X-ray mirrors. The mirror thickness can be extremely thin, of the order of 100 µm to 10 mm. The micropore optics can thus be ultralight weight. Three types of micropore optics are proposed and being developed.The first type is silicon pore optics (SPO) (Bavdaz et al. 2004(Bavdaz et al. , 2010 which is composed of flat silicon wafers with groove structures as mirrors. The wafers are stacked and elastically bent into a conical shape. This type is being developed aiming at an angular resolution of ∼10 arcsec for the future gigantic X-ray astronomy satellite Athena. 1 1 http://www.the-athena-x-ray-observatory.eu.Abstract A light-weight Wolter type-I telescope for future space X-ray observations is prototyped by using micromachining technologies. Curvilinear micro pores with a width of 20 µ m are fabricated with deep reactive ion etching. Sidewalls of the pores are smoothed with high temperature annealing. Then, two wafers are deformed to different curvature radii, 1000 and 333 mm. The two wafers are aligned using parallel X-ray beams which are dominated by Al-K α line at 1.49 keV. High angular and positional accuracies of the order of arcsec and µm are achieved using movable stages. The first clear X-ray focusing is confirmed. Its angular resolution is 4.1 arcmin in full width half maximum while it is at least 92 arcmin in half power width. The effective area is 19.0 mm 2 which is ∼5 times smaller than a model calculation. We discuss causes of the degraded angular resolution and effective area and also future improvements.

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Iridium-coated micropore x-ray optics using dry etching of a silicon wafer and atomic layer deposition

Cited by 18 publications

References 14 publications

Ultralightweight x-ray telescope missions: ORBIS and GEO-X

Ultralightweight x-ray telescope missions: ORBIS and GEO-X

Small satellites with MEMS x-ray telescopes for x-ray astronomy and solar system exploration

First X-ray imaging with a micromachined Wolter type-I telescope

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