An encoder head includes one or more components arranged to: i) direct a first incident beam to the diffractive encoder scale at a first incident angle with respect to the encoder scale; ii) receive a first return beam from the encoder scale at a first return angle, the first return angle being different from the first incident angle; iii) redirect the first return beam to the encoder scale as a second incident beam at a second incident angle; and iv) receive a second return beam back from the encoder scale at a second return angle, the second return angle being different from the second incident angle, in which a difference between the first incident angle and second incident angle is less than a difference between the first incident angle and the first return angle and less than a difference between the second incident angle and the second return angle.

Claims

32 · 1 independent · depth 9

32 granted claims

›1.independentAn encoder system comprising:nan encoder head for use with a diffractive encoder scale, wherein the encoder head comprises one or more optical compone…+31

›2.↳ 1The encoder system of claim 1, wherein the one or more optical components are arranged to combine the second return beam with a reference beam to form…d2+23

›3.↳ 2The encoder system of claim 2, further comprising an electronic processor configured to:nreceive an interference signal from the detector, the interfe…d3+22

›4.↳ 3The encoder system of claim 3, wherein the phase is a heterodyne phase.d4

›5.↳ 3The encoder system of claim 3, wherein the encoder head comprises a plurality of optical components, the plurality of optical components comprising a …d4+19

›6.↳ 5The encoder system of claim 5, wherein the plurality of optical components comprises a first optical component arranged to:nreceive the second return …d5+5

›7.↳ 6The encoder system of claim 6, wherein the plurality of optical components comprises a second optical component, and wherein the first optical compone…d6

›8.↳ 6The encoder system of claim 6, wherein the first optical component comprises a grating, the grating being operable to diffract both the first return b…d6+3

›9.↳ 5The encoder system of claim 5, wherein the the plurality of optical components comprises:na first retro-reflector; anda first optical component, the f…d5+2

›12.↳ 5The encoder system of claim 5, wherein the plurality of optical components comprise a first retro-reflector, and wherein the beam splitting component …d5+9

›13.↳ 12The encoder system of claim 12, wherein the first retro-reflector is arranged to:nreceive the reference beam from the beam splitting component; andred…d6+3

›17.↳ 12The encoder system of claim 12, further comprising a reference reflector arranged to receive, from the beam splitting component, the reference beam at…d6+4

›25.↳ 3The encoder system of claim 3, wherein the one or more optical components comprise a single optical component.d4

›26.↳ 1The encoder system of claim 1, further comprising the diffractive encoder scale.d2+1

›28.↳ 1The encoder system of claim 1, wherein each of the first return beam and the second return beam is a diffracted beam.d2+1

›30.↳ 1The encoder system of claim 1, wherein the first incident beam and the first return beam are non-collinear and non-parallel, and the second incident b…d2

›31.↳ 1A system comprising:na moveable stage; andthe encoder system of claim 1, wherein either the encoder system or the measurement object is attached to th…d2

›32.↳ 1A lithography system comprising:nthe encoder system of claim 1;a moveable stage, wherein either the encoder system or the measurement object is attach…d2

Classifications

5 codes

IPC · International Patent Classification

Section G — Physics

G01D5/26
G01D5/38
G03F7/20
G01B11/02

USPC · US Patent Classification

356/499

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Pendency

2.2 y

810 days filing → grant

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non-final + final

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1 RCE

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Examiner

Michael A Lyons

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Citations: 29 back · 0 forward

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Priority chain

2 priority documents

Priority

9 Nov 2011

earliest claimed

›Priority documents — 2

Type	Document	Date
provisional	US 61557755	9 Nov 2011
related publication	US 20130114061 A1	9 May 2013

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