Flash Measuring Machine

What the Machine Does

A flash measuring machine captures the entire field in a single exposure and measures every dimension on that image. There is no stage motion between features, so the cycle time does not grow with the number of dimensions measured.

That is the defining property. A vision measuring machine with a moving stage is accurate and general; a flash machine is fast and bounded by its field.

Why It Needs a Large Field and a Stable Scale

Because every dimension comes from one image, the field has to be large enough to contain the whole part, and the magnification across that field has to be known precisely. Any variation in scale between the centre and the edge becomes a measurement error that no repeated measurement removes.

Across the POMEAS measuring equipment that publishes it, field of view spans 0.15 to 200 mm depending on model, with working distance of 55 mm on the model that publishes it. The large end of the field range is what makes single-shot measurement of a small assembly practical.

Calibration Is the Whole Accuracy Story

The machine measures pixel positions and converts them using a calibrated scale. The accuracy of every result therefore depends on that scale being correct across the field, not only at one point.

Telecentric optics help here: the magnification of a telecentric system does not change with height, so a part that is not perfectly flat is still measured at the correct scale. A non-telecentric system changes scale with height, which produces an error that looks like a part defect.

Across the POMEAS measuring equipment that publishes it, distortion is 0.06 %, which is the figure that bounds the scale error across the field.

Lighting Decides the Edge

Every dimension is measured between edges found in the image, so the lighting has to produce an edge whose position is unambiguous.

For a silhouette, a telecentric parallel backlight gives an edge defined by geometry rather than by a threshold. For a surface feature, the lighting has to produce contrast at the feature without producing a gradient that shifts the found edge.

This is why a flash machine's accuracy on a new part family is not predictable from its specification: it depends on whether the part can be lit so that the edges are honest.

Where It Stops Working

It stops when the part does not fit the field, because stitching reintroduces motion and the cycle time advantage disappears.

It stops when the tolerance approaches the optical resolution, because no amount of averaging recovers detail the optics did not record.

And it stops when the feature is not visible from one direction, because a single-shot machine cannot see round a corner.

All three are part properties rather than machine defects, and all three are best established by sending sample parts rather than by comparing specifications.

What to Ask Before Buying

Ask for the field, the working distance, the object-space resolution, the distortion and the calibration method. Then ask for a demonstration on your parts, measured against a reference method you trust.

The demonstration is the only test that answers the question the purchase is about, because the specification describes the machine and the parts describe the application.

Where It Fits in a Production Line

It fits where the measurement is complete on a small part and the cadence is short: incoming inspection of a family of small components, in-process checks on a machined feature, and final verification where the whole part is visible.

It does not fit where the part is large or where the measurement requires several orientations, and in those cases a stage-based vision measuring machine remains the correct instrument.

Frequently asked questions

How does a flash measuring machine measure so quickly?

It captures the whole field in one exposure and measures every dimension on that single image. There is no stage motion between features, so cycle time does not grow with the number of dimensions.

Does it need a moving stage?

No, and that is the point. If the part does not fit the field, stitching reintroduces motion and removes the cycle time advantage.

Why is telecentric optics important for this measurement?

Because the magnification of a telecentric system does not change with height, so a part that is not perfectly flat is measured at the correct scale. A non-telecentric system changes scale with height.

What field of view is available?

Across the POMEAS measuring equipment that publishes it, the field spans 0.15 to 200 mm depending on model, with a working distance of 55 mm on the model that publishes it.

How accurate is it?

Accuracy depends on the calibration across the field, the object-space resolution and the distortion. Across the POMEAS measuring equipment that publishes it, distortion is 0.06 %. A demonstration on your own parts is the only reliable answer.

When should I choose a stage-based measuring machine instead?

When the part does not fit the field, when several orientations are required, or when the tolerance demands more than the single-shot optics can resolve.