1998 Lens Design Problem

The Solid Glass Lens

NOTE: This information was maintained by Optical Data Solutions

Summary (excepted from Optical Data Solutions)

The 1998 International Optical Design Conference (IODC) was held July 8-12, 1998 in Kona, Hawaii. It was co-sponsored by OSA and SPIE. The IODC traditionally includes one or more lens design problems for members of the optical design community to consider. This time, the design problem consisted of designing a solid glass lens with no intervening air spaces between the first and last surfaces of the lens. The definition/statement of the design problem can be found here (and below along with results from the competition).

A paper entitled “LENS DESIGN PROBLEM SUMMARY: The Solid Glass Lens” was published in SPIE Proceedings Volume 3482. This paper summarizes the design solutions submitted, highlights the best designs and considers some interesting points brought to light as a result of the endeavor. Since some of the optical prescriptions submitted as solutions were quite long, this web page is being provided as a companion piece to the paper published in SPIE Proceedings Volume 3482. This web page is not meant as a replacement for the information contained in the paper.

Introduction:

With the exception of some very successful solid catadioptric systems, the all-cemented objective has been neglected as a genre since the arrival of anti-reflection coatings. There are reasons for this: we depend heavily on the large refractive index differences between glass and air! This task promises to reveal just how important this dependence is to us. On the other hand, the air-glass interface only too easily leads to total internal reflection. In a sense, this task has a family relationship with the monochromatic quartet problem of the 1990 OSA Lens Design conference, in that for the latter problem it was clear that one was restricted to 8 air-glass interfaces – here you are restricted to 2. You will notice that in this task there is no restriction to refracting surfaces and it is anticipated that some of the solutions might be catadioptric.
– Jon Maxwell/Imperial College, London

Design Parameters:
Configuration solid (all-cemented) lens
no airspaces (except last lens surface to image)
in-line refractive or solid catadioptric
no plastic elements, no diffractives, no GRIN
F/number
(on-axis)
(paraxial)
in-line refractive: F/1.8
obscured systems MUST have an unobscured aperture AREA equivalent to an F/1.8 lens
any unobscured system with beamsplitter: F/1.3
Detector size
(non-paraxial)
50 mm circular
Focal length unspecified – set by mass constraint
Spectral band white light (C d F)
Spectral weights 656.3nm:1 587.6nm:1 486.1nm:1
Mass less than 1 Kg; Mass is to be calculated based on the size of the defined apertures on each surface. This may require that the lens edges be a series of tapered cones, connected by the different surface diameters. The entrant should have defined diameters for each surface, these are the same apertures used to calculate vignetting and edge thickness.
Relative Illumination greater than 70% at full field; RI defined as: (Number of rays successfully traced at max field integrated over the projected solid angle of the exit pupil at max field) divided by (Number of rays successfully traced on-axis integrated over the projected solid angle of the exit pupil on-axis)
Image surface flat (plane) (and in air)
Object at infinity (and in air)
Merit function M = on-axis geometric polychromatic RMS spot radius
+ 0.7 field geometric polychromatic RMS spot radius
+ 0.8 field geometric polychromatic RMS spot radius
+ 1/2(full field geometric polychromatic RMS spot radius)
Surface shapes spherical only
Materials catalog glasses only (e.g. Schott, Ohara, Hoya, …)
no plastics, no crystalline (e.g. MgFl etc.)
Edge thicknesses > 0 mm at maximum aperture consistent with vignetting and mass calculation.

Evaluation:

The merit function, M, will be evaluated based on polychromatic, geometric RMS spot size for the specified F/number (or T/number), spectral weighting, image size, and vignetting (relative illumination). Systems that exceed the mass requirement (computed using the supplied optical clear apertures or the minimum clear apertures required to meet the relative illumination requirement) will be penalized in the merit function by the CUBE of the computed weight divided by 1Kg. There is no competitive advantage to producing a system lighter than 1 Kg (unless of course it produces a better merit function). Lenses that do not meet the effective F/number, image size, or relative illumination requirements (within ~2%, as evaluated by the independent team described below) will not be considered in the competition.

Catadioptric solutions:

If there is a large discontinuity between in-line refractive and catadioptric designs, two separate categories may be created. The effective collecting area after accounting for obscuration must equal or exceed that of the equivalent unobscured system. Catadioptric solutions with beamsplitters will not be considered in the competition.

Noncompliant Designs:

Designs with noncompliant features such as diffractive surfaces, gradient index materials, nonspherical surfaces, liquid lenses, or materials that are not in the catalogs (any vintage) of a mainstream visible glass supplier will not be included in “the competition”, but at the discretion of the moderator/committee, may receive an honorable mention. The committee reserves the right to remove a lens from the “competitive” list that is more creative than we can currently anticipate.

Noncompliant designs – Diffractive surfaces:

There is already enough interest in diffractive solutions that they are likely to be an honorable mention category, so the following guidelines are provided. Diffractives should be placed on the external surfaces. The F/number of a design should be faster due to transmission of 90% per diffractive. Relative illumination should be higher, due to falloff of throughput with wavelength. The minimum line spacing should be greater than 5 microns.

Honorable Mention:

Some criteria for honorable mention might include, best design with the smallest number of glasses, best design with the largest number of glasses, design with the longest focal length, design with the highest, or lowest variation in focus with a 10 degree C temperature change.

Other Comments:

  • The stop can be anywhere in the lens system.
  • The focal length is not specified, it is controlled by the weight requirement
  • The image plane clearance need only be greater than 0
  • Distortion does not have a requirement
  • Glass transmission will be assumed to be 1.0
  • Lens units of mm is preferred

Results:

The following table contains prescription data in separate files. To view prescription files or comment files, left-click on the desired filename. To download prescription or comment files, right-click on the desired filename and choose “Save Link As…” (or similar depending on your browser) from the subsequent pop-up menu.

Files, Format, MF Value, General Comments, Designer's Comments
D29.seq, CodeV, 0.9, , CommD29.txt
D18.seq, CodeV, 1.0, , CommD18.txt
D03.len, OSLO, 1.3, , CommD03.txt
D11.zmx, ZEMAX, 1.4, , CommD11.txt
D05.len, OSLO, 3.0, , CommD05.txt
D26.zmx sumita.agf, ZEMAX, 4.9, Extra file needed in Zemax for Sumita Corp glasses,  CommD26.txt
D30.seq, CodeV, 5.1, , CommD30.txt
D27.zmx sumita.agf, ZEMAX, 5.6, Extra file needed in Zemax for Sumita Corp glasses,
D12.seq, CodeV, 6.0, , CommD12.txt
D28.zmx, ZEMAX, 7.4, ,
D09.zmx oldglas1.agf, ZEMAX, 8.5, Extra file needed in Zemax for older glasses, CommD09.txt
D23.len, OSLO, 10.7, , CommD23.txt
D13.zmx, ZEMAX, 15.5, , CommD13.txt
D17.zmx, ZEMAX, 15.5, , CommD17.txt
D40.zmx, ZEMAX, 17.1, ,
D33.seq, CodeV 19.8, , ,
D21.len, OSLO, 24.9, , CommD21.txt
D41.rle, SYNOPSYS, 25.9, , CommD41.txt
D16.seq, CodeV, 27.7, , CommD16.txt
D36.lns, SIGMA, 29.3, , CommD36.txt
D35.len, OSLO, 30.7, , CommD35.txt
D31.seq, CodeV, 35.0, , CommD31.txt
D32.seq, CodeV 35.3, , ,
D07.seq, CodeV, 44.8, , CommD07.txt
D37.zmx, ZEMAX, 55.0, , CommD37.txt
D22.rle, SYNOPSYS, 56.0, ,
D02.zmx, ZEMAX, 57.2, , CommD02.txt
D24.zmx, ZEMAX, 70.3, , CommD24.txt
D20.zmx, ZEMAX, 80.2, ,
D15.zmx, ZEMAX, 87.2,, CommD15.txt
D34.seq, CodeV, 97.1, , CommD34.txt
D08.zmx, ZEMAX, 97.2, ,
D38.zmx, ZEMAX, 138, , CommD38.txt
D14.zmx, ZEMAX, 139, ,
D01.zmx, ZEMAX, 160, Fails mass (penalty not incl. in MF), CommD01.txt
D06.zmx, ZEMAX, 216, , CommD06.txt
D25.zmx, ZEMAX, 350, 3 element solution, CommD25.txt

File: The identities of designers have been concealed by using the random assignment of an alpha-numeric list. In the summary IODC presentation and paper, only the top few names and affiliations will be revealed.Format: This column lists the format of the prescription file. This listing is necessary so readers of this page know how to translate the optical prescription file. It does not necessarily indicate that the design was optimized in that code.

MF Value: This column contains the estimate of the Merit Function. The numbers presented here were calculated by using a large number of rays in a rectangular sampling grid centered about the chief ray. It is acknowledged that centering the sampling grid about the centroid of the spot may have been a more appropriate choice and would have yielded slightly different performance numbers, but subsequent evaluation indicated that centroiding didn’t appear to change the relative ranking of designs.

Designer’s Comments: Most of the entrants were surveyed via electronic mail and asked to respond to a few short questions regarding their design problem submissions. Some their responses are contained here. Editing is minimal.

 

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