Biomedical Engineering Reference
In-Depth Information
TABlE 17.1
Statistical.Data.for.Dry.20×.(0.40.NA).and.Dry.40×.(0.75.NA).Objectives
No.
PV.(μm)
RMS.(μm)
S
S(14)
20×.1
0.595
0.092
0.267
0.595
20×.2
0.496
0.076
0.417
0.672
20×.3
0.876
0.127
0.11
0.593
20×.4
0.504
0.063
0.568
0.722
20×.5
0.853
0.097
0.314
0.627
20×.6
0.568
0.076
0.485
0.734
20×.7
0.878
0.127
0.18
0.627
20×.8
0.565
0.081
0.374
0.695
20×.9
0.506
0.089
0.286
0.726
20
×
Mean
0.649
0.092
0.334
0.665
40×.1
0.624
0.089
0.325
0.539
40×.2
0.627
0.076
0.457
0.664
40×.3
0.568
0.089
0.29
0.675
40×.4
1.371
0.161
0.051
0.285
40×.5
1.15
0.189
0.132
0.389
40×.6
1.299
0.132
0.169
0.415
40
×
Mean
0.940
0.123
0.237
0.494
PV, Peak-to-valley; RMS, root-mean-square; S, Strelh; S(14), Strehl ater correcting irst 14 Zernike modes
embryo..he.measurement.error.for.the.SHWF.sensor.was.measured.to.be.less.than.5%.of.the.wavelength.
at.647.nm..his.was.measured.by.repeating.a.single.measurement.10.times.and.measuring.the.RMS.error.
for.that.one.data.point..Measurements.20×.1-9.were.taken.with.a.20×.objective;.measurements.40×.1-6.
were.taken.with.a.dry.40×.objective..he.measurements.show.a.maximum.PV.wavefront.error.of.0.88.
and.1.37.μm.for.the.20×.and.40×.lenses,.respectively..he.maximum.RMS.wavefront.error.was.0.13.and.
0.19.μm.for.the.20×.and.40×.objective.lenses,.respectively..his.demonstrates.only.some.of.the.typical.
aberrations.that.can.be.encountered.for.the.
Drosophila melanogaster
.sample..For.a.similar.study.on.some.
of.the.early.phases.of.this.work,.please.see.Azucena.et.al..(2010)..he.higher.PV.and.RMS.measurement.
in.the.40×.objective.are.mainly.due.to.the.spherical.aberrations.introduced.by.the.higher.NA.lens..Table.
17.1.also.shows.the.Strehl.ratio.(column.four).obtained.by.inding.the.global.maximum.of.the.PSF.image.
for.each.measurement.using.a.search.algorithm.in.MATLAB®..By.removing.diferent.Zernike.modes,.we.
can.also.approximate.the.efect.of.removing.diferent.amounts.of.wavefront.error..Column.5.in.Table.17.1.
demonstrates.the.efect.of.removing.the.irst.14.Zernike.modes.from.each.measurement..he.data.show.
that.correcting.a.small.number.of.modes.improves.the.imaging.capabilities.of.the.system.
Figure.17.11
.shows.the.statistical.data.for.each.Zernike.mode.for.the.measurements.shown.in.Table.17.1..
he.data.show.a.gradual.decrease.in.value.with.increasing.Zernike.mode..From.this.we.can.verify.that.low-
order.aberrations.are.the.main.source.of.wavefront.error.and.that.the.aberration.values.are.higher.in.the.40×.
objective..he.gradual.decrease.in.the.strength.of.each.Zernike.value.for.higher.Zernike.modes.shows.that.
there.is.little.wavefront.aberration.introduced.for.modes.higher.than.25,.which.is.well.within.the.range.of.our.
sensing.capabilities..Note.that.the.spatial.resolution.for.the.wavefront.measurement.setup.for.the.40×.objective.
with.a.limiting.aperture.
D
.=.3.mm.is.the.Zernike.mode.100..his.helps.to.verify.the.simulation.results.obtained.
in
.
Figure.17.10
.
that.correcting.only.a.few.low-order.Zernike.modes.helps.to.improve.the.Strehl.ratio.by.at.least.
a.factor.of.two..his.point.will.also.be.shown.again.in.our.correction.of.the.wavefront.that.follows.
17.2.3 Wavefront corrections
Validation.of.the.wavefront.measurements.can.be.obtained.by.correcting.the.wavefront.and.thus.closing.
the.loop.in.our.system..
Figure.17.12
.shows.the.results.of.the.correction.steps,.where.each.correction.step.
