the power of negative thinking in optical design
TRANSCRIPT
![Page 1: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/1.jpg)
The Power of Negative Thinking
Dave ShaferDavid Shafer Optical Design
![Page 2: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/2.jpg)
• Part I - review of material that I have given before. Required background for Part II
• Part II - new ideas and designs
Plan for talk, in 2 parts
![Page 3: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/3.jpg)
The final $1,000,000 question is in two parts – an easy part and a hard part. Which part do you want first?
![Page 4: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/4.jpg)
“and when was he born?”
![Page 5: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/5.jpg)
• Limiting aberrations for highly corrected designs =
higher-order Petzval and sagittal oblique spherical aberration
• Mostly induced aberrations, not intrinsic
![Page 6: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/6.jpg)
Mirror has Spherochromatism
Incoming ray angle and conjugate change with wavelength
![Page 7: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/7.jpg)
• Chief ray aberrations inside design cause induced higher-order Petzval curvature
• Rays have different angles and surface intersection heights than 3rd-order assumes
• 3rd-order assumes paraxial quantities
![Page 8: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/8.jpg)
Chief rays aimed at paraxial pupil
![Page 9: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/9.jpg)
Inverse triplet – small chief ray aberration
![Page 10: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/10.jpg)
Nearly concentric, nearly aplanatic Nearly aplanatic, nearly concentric
Reason for very small chief ray aberration
Paraxial pupil
![Page 11: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/11.jpg)
3rd-order triplet field curves
3rd-order inverse triplet field curves, 20X smaller scale
All 3rd-order = 0 for both designs, not ray optimized
![Page 12: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/12.jpg)
All to same scale, same F.L.
Triplet has smallest lens volume, longest back focus, worse chief ray aberrations, worst field aberrations
•Double-Gauss has shortest back focus, best aperture aberrations, about same field aberrations as triplet.
•Inverse triplet has largest lens volume, best chief ray aberrations, best field aberrations
![Page 13: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/13.jpg)
Induced oblique spherical aberration has a different cause =
astigmatism and Petzval between surfaces
results in beam footprint on each surface that changes shape and conjugates with field angle
![Page 14: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/14.jpg)
Front surface footprint Middle surface footprint Last surface footprint
Triplet with all 3rd-order = 0
Field curves
![Page 15: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/15.jpg)
Petzval and astigmatism of front lens makes beam footprint elliptical on next lens. Effect increases with lens separations. Off-axis tangential rays see less overcorrected spherical aberration from negative middle lens because Y beam width is smaller than X beam width. Rear lens is affected same way.
Next surface
Front lens by itself
Middle lens beam footprint at edge of field
• This is an induced aberration effect, not an intrinsic one • 3rd-order assumes round beams on each surface and no change in size with field angle• Result is bad oblique aberrations
![Page 16: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/16.jpg)
All 3rd-order = 0
On-axis footprint
Edge of field footprint
Middle lens footprints
![Page 17: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/17.jpg)
Ray optimized triplet
Front surface footprint Middle surface footprint Last surface footprint
10X smaller scale than 3rd-order triplet plotPetzval radius = 2.7 X f.l.
![Page 18: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/18.jpg)
• Ray-optimized triplet has about 20X better performance than 3rd-order triplet, for this field and aperture example
•Ray optimized design has beam footprints nearly circular, not elliptical
•Much closer to 3rd-order assumptions = smaller induced aberrations = better performance
•But chief ray aberrations only slightly improved.
•Diameter of circular footprint changes with field, due to Petzval, so still gives induced aberrations
3rd-order triplet ray-optimized triplet
Front
Middle
Back
Beam footprints at edge of field
![Page 19: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/19.jpg)
In complicated optical systems both the intrinsic and the induced aberrations can all cancel out, at the 5th-order level.
This looks sort of like the triplet but
• the beam compression is much more at the middle negative lens
• the lens powers are much stronger, especially the strong negative lens
• rays fail at larger field angles
With right glasses can also correct for axial and lateral color
All 3rd = all 5th = 0.0No ray optimization
![Page 20: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/20.jpg)
• At least 6 lenses are necessary to correct all the 3rd and 5th order aberrations to 0.0, if no aspherics are used
• Need that many design variables
• Many 6 element solutions exist but most have strong curves and limited potential – bad 7th order
• More elements helps, gives weaker curves
• First order configuration helps the most.
• No solutions seem to exist with long back focus, regardless of number of lenses
![Page 21: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/21.jpg)
Double Gauss cannot be corrected for all the 3rd and 5th, regardless of number of lenses, because back focus is too big and wrong first-order configuration
![Page 22: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/22.jpg)
22
![Page 23: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/23.jpg)
23
This lens form is very versatile and can cover both fast speeds and wide angles with good performance, with no vignetting
f/2, 60 degrees, no vignetting f/1.25, 35 degrees, no vignetting
High performance design where index difference is important
![Page 24: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/24.jpg)
TV projection lens. Aberration corrector - focusing lens - field lens
![Page 25: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/25.jpg)
• In an ideal world every element has power, astigmatism, and Petzval independent of each other
• Gives great control over induced aberrations inside design
• Diffractive and aspheric surfaces can provide this
![Page 26: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/26.jpg)
100 mm EFL, diffractive and aspheric surfaces
![Page 27: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/27.jpg)
Diffraction-limited monochromatically
![Page 28: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/28.jpg)
Part II - new ideas
![Page 29: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/29.jpg)
Cooke triplet again
Consider effect of splitting lenses
![Page 30: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/30.jpg)
30
A typical lithographic 4X stepper lens design, from 2004. It is .80 NA, 1000mm long, has 27 lenses and 3 aspherics. The 27 mm field diameter on the fast speed end has distortion of about 1.0 nanometer, telecentricity of about 2 milliradians, and better than .005 waves r.m.s. over the field at .248u. More modern designs have more aspherics and fewer lenses.
![Page 31: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/31.jpg)
No aspherics or diffractive surfaces. Large index differences
Lens powers = alternating - + - + - +
![Page 32: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/32.jpg)
Diffraction limited, 100 mm EFL, f.2.0, 30 degree field, no vignetting. Long back focus.
![Page 33: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/33.jpg)
Axial and lateral color corrected
![Page 34: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/34.jpg)
Achromatic with no extra lens
![Page 35: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/35.jpg)
.35 NA, no aspheres or diffractive surfaces
![Page 36: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/36.jpg)
100 mm EFL, .35 NA, 30 degree field, no vignetting
![Page 37: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/37.jpg)
50 mm EFL, f/2, 45 degrees field, no vignetting
No diffractive surface but strong aspherics
![Page 38: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/38.jpg)
50 mm EFL, f/2, 60 degrees field, no vignetting
![Page 39: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/39.jpg)
50 mm f.l. , f/2, 60 degree field, no vignetting
![Page 40: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/40.jpg)
. Color corrected design Alternate color corrected design
![Page 41: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/41.jpg)
Achromatic performance, 50 mm f.l. , f/2, 45 degrees, no vignetting
![Page 42: The power of negative thinking in optical design](https://reader035.vdocument.in/reader035/viewer/2022062304/55d4ef53bb61eb8b438b4693/html5/thumbnails/42.jpg)