Case Study: PYRITE 85 mm Machine-Vision Surrogate

This page documents the surrogate layout Machine Vision 85 mm Pyrite (Datasheet 1X). It is based on the local datasheet:

~/Downloads/PYRITE_45_85_05x-20x_V38_1072517_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 85 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 4.5/85/0.5x-2.0x V38, ID 1072517	Menu title and documentation identity
Effective focal length	85.13 mm	Paraxial effective focal length
Magnification range	0.5x to 2.0x, nominal 1x	Default layout is the 1x conjugate
F-number range	F/4.5 to F/8	Default aperture is F/4.5
Numerical aperture	0.06 object side, 0.06 image side	Sanity check for the F/4.5 finite-conjugate model
Maximum sensor size	62.5 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	100 mm to 228 mm	Checked against the 0.5x to 2.0x model conjugates
SF	-62.45 mm	Front focal distance from the first optical vertex
S'F'	63.18 mm	Back focal distance from the last optical vertex
HH'	-5.12 mm	Principal-plane separation
SEP / S'AP	22.02 mm / -22.62 mm	Stop placement sanity check
Σd	39.52 mm	Rounded optical vertex span; model uses the exact STEP glass span that rounds to this value

The mechanical drawing also shows a 47.8 mm barrel length, 142.9 mm working distance and 149.4 mm image-side distance at beta prime -1.0. The surrogate’s table distances are measured from optical vertex datums, not from the external mechanical shoulders, so they are close but not identical to those mechanical drawing dimensions.

Vendor STEP Overlay

The preset also records the local vendor STEP file:

attachment/Lens/1072517_00165969_001.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/F1030	First glass surface / front optical vertex	+21.705462655 mm
S001/F1032	Last glass surface / rear optical vertex	-17.817554103 mm

Those two surfaces are separated by 39.523016758 mm. That is the datasheet Σd = 39.52 mm rounded to the nearest 0.01 mm plus about 3 µm. 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 -3.547201484 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/4.5 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 62.5 mm image-circle capability.

• The lens STEP overlay uses attachment/Lens/1072517_00165969_001.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 = -62.45 + 85.13 = 22.68 mm

The second principal plane is inferred from:

H2 = Σd + S'F' - f'eff = 39.52 + 63.18 - 85.13 = 17.57 mm

The resulting H2 - H1 is about -5.11 mm, matching the published HH' = -5.12 mm after rounding.

The surrogate rows are:

Row	Role	Distance / power
Object	1x finite object plane	147.58 mm before the first optical vertex datum
Front Optical Vertex Datum	First optical vertex reference	1.71545542 mm to group 1
Blackbox Group 1	Ideal thin-lens group	f = 150.17565687 mm
Aperture Stop F/4.5	Stop / F-number control	20.30454458 mm after group 1
Blackbox Group 2	Ideal thin-lens group	f = 148.63880626 mm
Rear Optical Vertex Datum	Last optical vertex reference	148.31 mm to image at 1x
Image / Sensor	1x sensor plane	62.5 mm image circle

The 1x layout is the default because the datasheet drawing explicitly labels the beta-prime -1.0 case. 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
0.5x	232.71 mm	105.745 mm
1.0x	147.58 mm	148.31 mm
2.0x	105.015 mm	233.44 mm

The published working-distance range is measured to the first mechanical element, so the 0.5x and 2.0x optical-vertex distances bracket the datasheet range with the expected mechanical offset.

Rendered Layout

The surrogate uses optical vertex datums, two blackbox thin-lens groups, an F/4.5 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, lock screws, 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/F1030 and S001/F1032 remain the matched first and last glass surfaces:

python -m KrakenOS.UI.validate_machine_vision_pyrite_85_surrogate