Daniel Malacara Optical Testing

7/30/2019 Daniel Malacara Optical Testing

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OPTICAL TESTING

, . .

eptem er,



TESTING OPTICAL ELEMENTS

¾Plane surfaces

¾Spherical surfaces

•Concave

•Convex

¾Aspherical surfaces

•Concave•Convex

¾Lenses and prisms



can be made only asgoo as you can es

Modern Instruments require

complicated shapes and deviations

of the wavelength of light



OPTICAL TESTING METHODS

•

Newton and Fizeau• wyman- reen

•Lateral Shearing

•

er ear ng•Multiple Beam

lass cal eometr c ests•Foucault•Ronchi

•Wire

•

Hartmann•Optical and Mechanical Profilometry



Newton and Fizeau

Interferometers



Tested and Reference

Interfering Wavefronts



Field due to interference between a

a) Wavefront under test and a

b) Reference flat wavefront



Irradiance in an interference pattern

a) Wavefront under test and a

b Reference flat wavefront



Newton Interferometer



Fizeau Interferometer



Optical Path Differencein a Fizeau Interferometer

t = Physical path difference

=



Testin Concave Surfaces



Lon itudinal Modes in a Laser with Cavity Length L



Visibilit in an Interferometer vs. OPD



Tw man-Green

Interferometer Twyman (1918)



Twyman-Green Interferometer



in a Twyman-Green


=



Coherence in a Twyman-Green Interferometer



in a Twyman-Green Interferometer



in a Twyman-Green Interferometer



-

Interferograms

of

r mary

Aberrations



a era ear

Other Shear

Interferometers



Wavefronts in Shear Interferometers



Interferometer



Optical Path Difference

in a Lateral Shear


=



For a small shear S

the optical path difference is

Hence radial shear interferometers

Measure the wavefront tilt in the shear direction



Wavefront Evaluation in Lateral Shear



Murty Lateral Shear Interferometer



Testing Concave Surfaces in

Murty Lateral Shear Interferometer



Interferograms

of

Aberrations



Foucault TestFoucault (1858)



Foucault or Knife Edge Test





Pattern

of anAs herical

Wavefront



Shape of Aspheric Wavefront



Ronchi Testonc



Ronchi Test



Ronchi Test



Ronchigram of Aspherical Surface



Hartmann TestHartmann (1900)



Hartmann Test



pattern of a

mirror



Wavefront Slope and Ray Tranverse Aberration



Relation between the wavefront slopes and the

ray transverse aberrations TA

= s ance rom wave ron o

measuring plane



Calculation of wavefront deformations from

ay ransverse a erra ons or

wavefront slopes



Newton Interferometer

Twyman-Green interferometer

Tests that measure wavefront slope

Lateral Shear interferometer

Ronchi Test

Hartmann test



Increasing PrecisionMultiple Beam

Interferometry



Two beam interferogram Multiple beam interferogram



Increasing Precision

Phase Shifting

Interferometry



Phase Shifting Interferometry

with a Twyman-Green Interferometer



rra ance vs. ase erence

in Phase Shifting Interferometry



Interferograms in Phase Shifting Interferometry



Detuning Insensitive Phase Shifting Algorithm



Phase Shifting Interferometry Mathematics

Phase

equa on:

amp ng

functions:



Detuning Insensitive Phase Shifting Algorithm



Wrapped Phase Obtained in




Unwrapped Phase from




TESTING ASPHERICAL SURFACES

Autocompensating Configurations



Autocollimating Configurations

For Conic Surfaces



Testing of Aspherical Convex Surface



Testing of Convex Hyperboloids




Null Compensators with

Lenses

Diffracting Elements



Interferograms of As herical Wavefronts

-



Dall Compensator

For Parabolic Mirrors



Lens Offner Compensator

for Parabolic Mirrors



Mirror Offner Compensator



Wyant Hologram Compensator

for Aspherical Surfaces




Non-Null Tests




d

Interferogram

(Nyquist limit

Exceeded)



with three different reference

spheres



Aspherical wavefront slopes

with three different reference spheres



For different

focus settings

(Different

spheres)



with a



Without linear carrier With linear carrier




Non-Null Tests

Infrared Interferometry

White Light Interferometry



Group formed by two waves

with different wavelengths



Group Length formed by two waves

with two different wavelengths



Conclusion:

Optical testing is an old but exciting field

of a tremendous practical importance.

many new developments are expected andur entl needed.



GGracias por suAtencion [email protected]

www.cio.mx

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Daniel Malacara Optical Testing