次世代観測装置用の新しい回折格子の開発状況 IV
海老塚 昇1, 岡本 隆之1, 細畠 拓也1, 山形 豊1, 佐々木 実2, 魚本 幸3, 島津 武仁3, 佐藤 慎也4, 橋本 信幸4, 田中 壱5, 服部 尭5, 尾崎 忍夫5, 青木 和光51 理化学研究所, 2 豊田工大・工, 3 東北大・工, 4 シチズン時計・研究開発センター, 5 国立天文台

Quasi-Bragg (QB) grating

Birefringence volume phase holographic (VPH) grating⎧⎪ π ( n⎫⎪S max − nS min ) tηS = sin ⎨⎬⎪⎩ Λ ( nS max + nS min ) sin 2θ S ⎪⎭2nP max − nP min ) cos2θ P(nS max − nS min )(=(nS max + nS min ) * 2sinθ S cosθ S = (nP max + nP min ) * 2sinθ P cosθ P⎧⎪ π ( n⎫P max − nP min ) t cos2θ P ⎪ηP = sin ⎨⎬⎪⎩ Λ ( nP max + nP min ) sin 2θ P ⎪⎭2

(nS max − nS min ) = (nP max − nP min ) cos2θ P(nS max − nS min ) = (nP max − nP min ) cos2θ P(nS max + nS min ) sin 2θ S (nP max + nP min ) sin 2θ Pcosθ Scosθ PS polarization

P polarization

Λ= 5µm, θ0= 45°, n1=1.0, n2=1.54, n3=1.0, t = 9 µm, Al: w = 50nm

Fabrication of QB grating by lamination of embossed mirror substrates
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Cure of adhesiveLiquid crystal VPH grating

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325nm He-Cd Laser
Beam expander

Half mirror

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Lamination andadhesion of mirror
substrates.

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Volume binary grating
"-$'./6GD45>8&8D6=&#   @AD?4>ΛM μmF μm.

Limitation of surface relief (SR) grating
sinθ0 = n sinθ1@E<@α -θ1 = sinθθ= α θ0@E<@α -θ1 E<@α θ0
@sinα cosθ1- sinθ1 cosαsinα cosθ0  sinθ0 cosα@6AEθ1 - cosθ0sinα E<@θ0  n sinθ1cosαE<@θ0 cosα
tanα E<@θ0 / @6AEθ1 - cosθ0S polarization@ θ0 ≤ Nθ  N@ θ0 ≤N@ θ0 ≤N@ θ0 ≤N
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P polarization

Λ=5µm, L&S=4.75:0.25 [µm], θ0=45°, n1=1.0, n2=1.54, n3=1.5, t = 9 µm

' ) $#%'$(($)+$!*" #'.') #, *#) $#(as a quasi-Bragg gratingClear resin(high refractive index)

Substrate
Single crystal
siliconBosch process(isotropic etching)
Cross section A-A’
Substrate

Removal of Si
Clear resin(low refractive index)

Mold of silicon
S polarization

A’Side view

FinishP polarization

Fabricated by Nanotechnology platform of Toyota
Institute of Technology.
Left: Λ=5.1µm, L=0.44 µm, t = 10 µm.
Right: Λ=5.1µm, L=0.80 µm, t = 20 µm.

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Λ=5µm, θ0=45°, n1=1.0, n2=1.54

A

Silicon mold for volume binary grating.

Hybrid grism for MOIRCS (Near infrared instrument for Subaru Telescope))D<E??4F8D<4>1@,8@1  μm)>4F8, )&@   μm)D<E?H8DF8J4@:>8
α N
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D7+   μm

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grating.

Summary(BF<?4> Eff. [%]Order λ-λ [µ?3Fabrication method of SR grating for RFT grating and MOIRCS hybrid grism,;4B8D6GFF<@:A9?4EF8D:D4F<@:

Substrate
Clear resin
Master grating

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Ultra-high precision machine(Nagase-I, NPIC-M200).

VPH grating→LC VPH grating

Replication

Single-crystal diamond tool.

FinishTest cuttings for condition setting (left), moldfor replication experiment (right). Work piece:
50×50 [mm].

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transmission gratingth~!K5D<7:D<E?

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