MV-CS050-10GM(NPOE)View part & specifications →Browse camera options →Home / Case studies / Screw thread pitch with telecentric optics
Application study · Fasteners and precision machiningScrew thread pitch: a telecentric test reporting less than 0.007 mm
The application-lab sheet reports less than 0.007 mm over a 19.34 × 16.21 mm field using a bi-telecentric lens and collimated backlight. The useful design lesson is how the optics produce a stable, high-contrast thread silhouette.
Stabilize scale and edge contrast before judging a tolerance.
- Field of view19.34 × 16.21 mm
- Image2456 × 2058 px
- Accuracy (as tested)< 0.007 mm
- Working distance73 mm
Test stationIncluded light holdersCameraLensLightPartField of view
Drag to rotate · scroll to zoomWalk through this setup 5 guided stops
From component to inspection
Understand each choice.
Choose a stop to frame the part in 3D and see why it belongs in this setup. The component notes and links remain available if 3D cannot load.
Proposed component
MV-CS050-10GM(NPOE)
Same sensor format as the test camera: 5 MP, 2/3", 3.45 µm, monochrome (2448 × 2048 px).
Tested component
LS-VCM230-26
Bi-telecentric, 0.438x, made for 2/3" sensors.
Tested component
LS-VCL-26-XW-Y
Collimated light matched to the lens's 26 mm field; the test used the green version.
Proposed component
LS-BT-XZ-G-6-6045
600 mm column, 600 × 450 mm breadboard, XZ adjustment, glass tray and two lighting holders as listed. Proposed bench fixture; confirm loads, travel and camera/lens clamps.
Inspect the real capture
Follow the contrast to the part.
Stabilize scale and edge contrast before judging a tolerance.
Camera and available lens CAD are published models. Lens and light envelopes use printed dimensions. The linked station uses its published base size and column height; carriage, brackets, fittings, parts and spacing are illustrative. Confirm load, travel, fasteners and clearances before ordering. Light paths explain the arrangement and do not simulate optical performance.
From the demo to your test benchCameraMV-CS050-10GM(NPOE)View part & specifications →Browse camera options → Imaging lens
LS-VCM230-26View part & specifications →Browse imaging lens options → Inspection light
LS-VCL-26-XW-YView part & specifications →Browse inspection light options → Test station & mounts
LS-BT-XZ-G-6-6045View part & specifications →Browse test station & mounts options →
Build around the parts you can buy.
Explore each component, check its specifications and compare alternatives. The proposed quote includes the linked test station; its catalog listing includes two lighting holders.
MV-CS050-10GM(NPOE)View part & specifications →Browse camera options →LS-VCM230-26View part & specifications →Browse imaging lens options →LS-VCL-26-XW-YView part & specifications →Browse inspection light options →LS-BT-XZ-G-6-6045View part & specifications →Browse test station & mounts options →Mount the optics with intent
The station is an optical test bench, with its two lighting holders included in the catalog listing. The 3D column and base follow the published height and footprint. Carriages, clamps and part supports are schematic: confirm camera screw pattern, lens support, light fasteners, permissible load and actual travel before ordering.
Configure the mounting station →Complete the electrical system
This collimated light requires the specified constant-current driver configuration. Confirm current, colour, connector and power before selecting a controller; a general 24 V voltage controller is not a substitute. Camera cables and PC are separate selections.
Optics application-lab test sheet
Evidence you can inspect
Visible in the images
The source camera capture shows the thread as a high-contrast silhouette.
What the source reports
<0.007 mm over 19.34 × 16.21 mm, at 2456 × 2058 pixels, as stated on the source sheet.
How to use this evidence
A reported application-lab result. It is not a guaranteed tolerance for the proposed camera or a production measurement study.
What the camera saw
Cropped from the source test sheet; original test annotations are retained. Captures are not generated or enhanced. Drag the comparison slider or use the image buttons.
The challenge
Pitch, crest and root measurements need edges that do not move when the screw sits a little higher or lower in the fixture. With a standard lens, a part that is closer looks bigger, and the flanks of a thread blur where they leave the focal plane.
Front lighting makes it worse: the machined flanks reflect unevenly, so the edge the software finds depends on surface finish rather than geometry.
How it was solved
The test identifies the LS-VCM230-26 bi-telecentric lens and a green collimated backlight from the LS-VCL-26 family. Its source camera is 5 MP with a 2/3-inch sensor; the camera below is a current proposed alternative, not the source camera.
The lens reduces magnification changes with object distance, while the backlight puts the thread edges against a bright field. The reported field and image width correspond to approximately 7.9 µm per pixel (19.34 mm / 2456 px).
Why it works
- 1
Telecentric optics reduce perspective and scale changes within their specified operating range. Calibration and part alignment still matter.
- 2
Collimated backlighting limits edge wraparound and provides a useful silhouette for edge-based measurements.
- 3
The source reports <0.007 mm but gives no uncertainty budget, repeatability sample or edge-fitting method. Pixel sampling alone does not establish measurement accuracy.
From image contrast to a production decision
What to validate on your part
A useful sample image is the starting point. These are the checks that turn the concept into a defensible inspection.
- 01
Establish scale
Calibrate with a traceable artefact at the actual part plane and aperture.
- 02
Check repeatability
Repeat loading, rotate the part and vary height within the required fixture range.
- 03
Budget uncertainty
Include calibration, edge extraction, pose, thermal drift and part variation.
Explore your inspection requirementsNo limit from motion
How many pixels cover your feature?
Compare feature coverage, camera pixel requirements and exposure using your own planning inputs. These are calculated planning values, not inspection results or an accuracy specification.
Editable planning scenario. Adjust these example inputs for your application; they are separate from the source test and 3D setup. Motion allowance and target coverage are starting points to validate, not acceptance limits. Pixel count starts from the proposed camera's catalog resolution.
Enter finite numbers in every field. Field width, feature width, target coverage, exposure and allowed motion must be greater than zero; horizontal pixel count must be a positive whole number; material speed may be zero. Use values within the supported numeric range if a calculation cannot be represented.
Object sampling mm/px
Pixels across feature px
Horizontal pixels for target px
Motion during exposure px
Exposure ceiling from motion µs
Formulas and assumptions
The field, feature, speed and exposure start with neutral example values. They are not taken from the source test or the 3D illustration. Allowed motion starts at an editable 0.5-pixel example; it is not a recommended acceptance limit. Target coverage starts at an editable 5-pixel example; it is not a recommended detection or measurement threshold. The horizontal pixel count starts from the catalog Resolution row for MV-CS050-10GM(NPOE). Use the effective width after cropping, binning or decimation if those modes are enabled.
- Object sampling (mm/px) = field width (mm) / horizontal pixels.
- Pixels across feature = feature width (mm) / object sampling (mm/px).
- Horizontal pixels for target = field width (mm) × target pixels across feature / feature width (mm), rounded up to a whole pixel.
- Motion (px) = speed (mm/s) × exposure (µs) / 1,000,000 / object sampling (mm/px).
- Exposure for allowed motion (µs) = allowed motion (px) × object sampling (mm/px) / speed (mm/s) × 1,000,000.
The exposure result is the maximum duration from this motion allowance alone. At zero speed, motion sets no exposure limit; the camera, lighting, saturation and other constraints still apply. A shorter exposure does not itself guarantee a reliable inspection.
Field width and feature width refer to the same object plane. The motion calculation assumes uniform linear motion parallel to the field-width direction and a single exposure. It does not model perspective, vibration, rolling-shutter distortion, diffraction, defocus or optical distortion. A strobe may change the effective exposure.
The target result is a horizontal sampling requirement, not a camera recommendation or a change to the selected camera. It uses the effective image width after cropping, binning or decimation and does not determine the vertical resolution or sensor size. Pixel coverage alone does not establish detectability or measurement accuracy. Validate contrast, lens performance, working distance, illumination, calibration, camera exposure limits and the inspection algorithm on representative parts. Changing field width does not change the 3D model or certify that the proposed lens can achieve that field.
The set-up and the parts
| Camera (test) | 5 MP, 2/3", 3.45 µm pixels |
|---|---|
| Lens | Bi-telecentric, 0.438x, C-mount |
| Light | Collimated (telecentric) backlight, green |
| Working distance | 73 ± 1 mm (lens spec) |
| Depth of field | ± 2.3 mm @ F11 (lens spec) |
| Mounting (proposed) | LS-BT-XZ-G-6-6045 · camera test station with glass tray and two lighting holders |
LensTestedLS-VCM230-26
Bi-telecentric, 0.438x, made for 2/3" sensors.
$999.00In proposed setupLightTestedLS-VCL-26-XW-Y
Collimated light matched to the lens's 26 mm field; the test used the green version.
$289.00In proposed setupCameraOur pickMV-CS050-10GM(NPOE)
Same sensor format as the test camera: 5 MP, 2/3", 3.45 µm, monochrome (2448 × 2048 px).
$819.00In proposed setupCamera test stationOur pickLS-BT-XZ-G-6-6045
600 mm column, 600 × 450 mm breadboard, XZ adjustment, glass tray and two lighting holders as listed. Proposed bench fixture; confirm loads, travel and camera/lens clamps.
$359.00In proposed setup"Tested" identifies the part named in the source. "Our pick" is a proposed alternative or supporting part. The quote includes only cards marked "In proposed setup", with the quantities shown; other test arrangements are separate. Confirm colour, optics, controllers, power supplies, cables and mounting before ordering.
About this case study: the photos and camera images come from the application laboratory of the maker of the lighting and optics we sell, imaged on the parts shown; your results depend on your part, camera and set-up. This is an application-lab study, not a LumaSpec customer deployment. Source figures are reported results; proposed components require a fresh trial. The 3D scene illustrates the arrangement and does not simulate imaging performance.
Guides
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