Case Study: PYRITE 120 mm Machine-Vision Surrogate

This page documents the surrogate layout Machine Vision 120 mm Pyrite (Datasheet 1X). It is based on the local datasheet:

attachment/Lens/PYRITE_56_120_10x_V38_1097277_datasheet.pdf

What The Surrogate Is

The vendor datasheet does not provide the internal prescription. The KrakenOS layout is therefore a first-order blackbox model, not a decoded Schneider prescription. It uses two ideal thin-lens groups and one aperture stop inside the published optical vertex span. The goal is to make the UI behave like the 120 mm machine-vision lens at the level needed for layout work, field sampling, camera-distance studies, and Open 3D placement.

The model uses these public datasheet values:

Quantity

Datasheet value

Surrogate use

Product

PYRITE 5.6/120/1.0x V38, ID 1097277

Menu title and documentation identity

Effective focal length

120.68 mm

Paraxial effective focal length

Magnification range

-1.0 recommended, -1.125 to -0.875 usable

Default layout is the 1x conjugate

F-number range

F/5.6 to F/64

Default aperture is F/5.6

Numerical aperture

0.05 object side, 0.05 image side

Sanity check for the F/5.6 finite-conjugate model

Maximum sensor size

90 mm

Image and object row diameter; the default sampled field uses the shared camera workflow below

Maximum angle of view

21 degrees

Field sanity check

Working-distance range

198 mm to 228 mm

Checked against the recommended magnification range

SF

-94.33 mm

Front focal distance from the first optical vertex

S'F'

94.33 mm

Back focal distance from the last optical vertex

HH'

-1.78 mm

Principal-plane separation

SEP / S'AP

26.21 mm / -26.48 mm

Stop placement sanity check

Σd

50.91 mm

Rounded optical vertex span; model uses the exact STEP glass span that rounds to this value

Vendor STEP Overlay

The preset also records the local vendor STEP file:

attachment/Lens/1097277_00155156_002.stp

The STEP is used as a mechanical overlay, while the KrakenOS table remains the paraxial blackbox optical surrogate. OpenCascade extraction finds the two usable glass vertex surfaces as:

STEP face

Role in this surrogate

STEP local axis coordinate

S001/F193

First glass surface / front optical vertex

+8.832740626 mm

S001/F155

Last glass surface / rear optical vertex

-42.077263665 mm

Those two surfaces are separated by 50.910004290 mm. That is the datasheet Σd = 50.91 mm rounded to the nearest 0.01 mm plus about 4 nm. The surrogate uses the exact STEP glass span for its front-to-rear vertex distance, which still rounds to the datasheet value. It also stores a lens STEP placement offset of -3.137787154 mm so the STEP’s first and last glass vertices overlay the surrogate’s front and rear optical vertex datums. The mechanical front shoulder of the STEP is intentionally not used as the optical datum.

Default UI Settings

The preset intentionally follows the same working defaults as Machine Vision 150Mm Measured so the two layouts can be used the same way in Open 3D. It inherits the same ray display, source, detector, non-sequential, tolerance, atmosphere, optimization, and CAD overlay defaults. In particular, it opens with the same Allied Vision hr25MCX camera model and attachment/Cameras/3D_CAD_HR25xCXP.STEP camera overlay.

Only lens-specific defaults differ from the 150 mm measured layout:

  • The aperture default is F/5.6 from the PYRITE datasheet.

  • The real-image field default is 11.52 mm so the initial field sampling matches the shared camera workflow rather than the full 90 mm image-circle capability.

  • The lens STEP overlay uses attachment/Lens/1097277_00155156_002.stp and the glass-vertex alignment offset described above.

  • The auxiliary Open 3D optical STEP overlay is left empty; this avoids loading an unrelated extra CAD component from the 150 mm development layout.

How The Blackbox Is Built

The first principal plane is inferred from:

H1 = SF + f'eff = -94.33 + 120.68 = 26.35 mm

The second principal plane is inferred from:

H2 = Σd + S'F' - f'eff = 50.910004290 + 94.33 - 120.68 = 24.560004290 mm

The resulting H2 - H1 is about -1.79 mm, matching the published HH' = -1.78 mm after rounding.

The surrogate rows are:

Row

Role

Distance / power

Object

1x finite object plane

215.01 mm before the first optical vertex datum

Front Optical Vertex Datum

First optical vertex reference

17.760867505 mm to group 1

Blackbox Group 1

Ideal thin-lens group

f = 153.305042833 mm

Aperture Stop F/5.6

Stop / F-number control

8.449132495 mm after group 1

Blackbox Group 2

Ideal thin-lens group

f = 448.895372088 mm

Rear Optical Vertex Datum

Last optical vertex reference

215.01 mm to image at 1x

Image / Sensor

1x sensor plane

90 mm image circle

The same cardinals imply these finite-conjugate working points when measured from the optical vertex datums:

Magnification

Object to front optical vertex

Rear optical vertex to image

0.875x

232.25 mm

199.925 mm

1.0x

215.01 mm

215.01 mm

1.125x

201.601111 mm

230.095 mm

Rendered Layout

PYRITE 120 mm machine-vision surrogate layout

The surrogate uses optical vertex datums, two blackbox thin-lens groups, an F/5.6 stop, and the 1x image plane. It is meant for layout and camera placement studies, not manufacturing-level lens analysis.

Known Limits

  • Internal curvatures, glasses, aspheres, coatings, tolerances, and MTF are not reconstructed from the datasheet.

  • The two thin-lens groups reproduce first-order cardinal data; they do not reproduce the vendor’s high-resolution aberration correction.

  • The mechanical V38 mount, filter thread, and barrel outline are represented by the STEP overlay rather than by the sequential surrogate rows.

  • The STEP overlay is for placement and clearance. The ray trace still uses the two-thin-group blackbox unless the STEP is promoted/rebuilt as native optical surfaces with explicit glass assignments.

Validation

The validation script checks that the layout is discoverable in the Machine Vision menu and that the two-thin-group paraxial matrix reproduces the published effective focal length, front focal distance, and back focal distance. It also loads the vendor STEP and checks that S001/F193 and S001/F155 remain the matched first and last glass surfaces:

python -m KrakenOS.UI.validate_machine_vision_pyrite_120_surrogate