Biomedical Engineering Reference
In-Depth Information
Boston. Micromachines. commercialized. continuous. and. segmented. MEMS. DMs. based. on. the.
.prototypes.developed.at.Boston.University.that.used.a.three-layer.polysilicon.surface.micromachining.
process. (Bifano. 1996,. Krishnamoorthy. 1999,. Bifano. 2002,. Perreault. 2002,. and. Cornelissen. 2006. and.
2009).. he. prototypes. used. a. standard. process. and. the. commercialization. involved. revisions. to. the.
standard.process.to.make.commercial.products..Cross.sections.of.the.Boston.Micromachines.DMs.are.
shown.in.Figure.8.32.
Boston. Micromachines. currently. ofers. MEMS. continuous. facesheet. DMs. with. 32. actuators. in. a.
6.×.6.array.(i.e.,.without.the.four.corner.actuators),.140.actuators.in.a.12.×.12.array,.and.1020.actua-
tors.in.a.32.×.32.array..hese.are.currently.the.highest-order.MEMS.continuous.facesheet.mirrors.on.
the.market..Nonetheless,.they.have.a.stroke.that.is.limited.to.1.5-5.5.μm,.as.shown.in.Table.8.3,.and.
approximately.0.5.μm.of.stroke.must.be.used.to.latten.the.initial.curvature.in.the.mirror..In.addition,.
a.custom-built.4096.actuator.array.with.a.25.mm.aperture.and.4.μm.of.stroke.is.under.development.
for.the.Gemini.Planet.Imager.(GPI).(Cornelissen.2006,.2009,.2012,.Poyneer.2011).
Electrostatically
actuated
diaphragm
Attachment
post
Membrane
mirror
Continuous mirror
Segmented mirrors
(
piston
)
FIGuRE 8.32
Top
:.A.continuous.membrane.mirror.that.is.attached.by.posts.to.an.electrostatically.actuated.dia-
phragm. that. is. clamped. to. the. substrate.. Below. the. electrostatically. actuated. diaphragm,. isolated. counter. elec-
trodes.are.used.to.selectively.actuate.portions.of.the.mirror..
Middle
:.he.cross.section.shows.a.segmented.mirror.
that.has.piston.only.(up-down).actuation..
Bottom
:.he.cross.section.shows.just.the.actuators..he.middle.actuator.
is.delected.in.each.of.the.cross.sections..(Credit:.Boston.Micromachines,.MA.)
TABlE 8.3
Speciications.for.Boston.Micromachines.Continuous.Facesheet.Deformable.Mirrors
Array.Size.(Order) 32.(Mini-DM)
140.(Multi-DM) 1020.(Kilo-DM)
Stroke.(μm) 1.5 3.5 5.5 1.5 3.5 5.5 1.5
Aperture.(mm) 1.5 2.0 2.25 3.3 4.4 4.95 9.3
Pitch.(μm) 300 400 450 300 400 450 300
Response.Time.(μm) 20 100 500 <20 <100 <500 <20
Inter-actuator.Coupling.(%) 15 13 22 15 13 22 15
he.32
×.32.array.(kilo-DM).is.also.ofered.as.a.segmented.mirror.with.piston.(vertical).actuation.on.each.segment.for.use.
as.a.spatial.light.modulator.
