A profile projector — also called an optical comparator, shadowgraph, or contour projector — is a precision metrology instrument that magnifies the silhouette of a workpiece and projects it onto a screen for measurement. It is the industry workhorse for fast, non-contact 2D inspection of cutting tools, threads, gears, stampings, plastic mouldings, rubber gaskets, and small machined parts.
This guide covers how profile projectors work, the difference between vertical and horizontal models, Mitutoyo's range (PJ-A3000, PV-5110, PH-A14, PH-3515F), magnification selection, the JIS B 7184 accuracy framework, edge detection, mylar overlay charts, calibration in Australia, and how the technology compares to vision measuring systems and CMMs. The article is written for AU toolrooms, inspection engineers, quality managers, and maintenance teams responsible for capital equipment specification.
What is a profile projector?
A profile projector is an optical measurement instrument that uses a light source, telecentric optics, and a system of mirrors and lenses to project a magnified silhouette of a workpiece onto a large translucent screen. The operator then measures features on the screen — directly with a digital readout, by comparison against a mylar overlay chart, or by reading a built-in protractor scale.
The instrument has three common names. Profile projector is the technical name used in JIS B 7184 and most international literature. Optical comparator is the historically dominant American name, reflecting the original comparison-against-overlay-chart workflow. Shadowgraph is the older colloquial name, reflecting the silhouette-on-screen physics. The Wikipedia entry, the Mitutoyo catalogue, the Keyence reference library, and Practical Machinist forum threads all use these terms interchangeably for the same instrument.
Profile projectors sit alongside coordinate measuring machines (CMMs), vision measuring systems (VMS), surface roughness testers, roundness testers, and linear encoders in the metrology stack. They are usually the fastest, simplest, and lowest-cost option for 2D feature inspection on small parts.
How a profile projector works
A profile projector works by passing a beam of light past a workpiece, through a telecentric projection lens, off one or more mirrors, and onto a translucent screen — magnifying the part's silhouette so features can be measured with high precision. Telecentric optics are critical: they project parallel light rays, eliminating perspective distortion and meaning the size of the projected image does not change as the workpiece moves slightly toward or away from the lens.
The basic optical path is light source → condenser → workpiece on glass stage → projection lens → mirror(s) → screen. The workpiece sits on a precision X-Y stage (manual micrometer-driven or motorised) and the operator moves the stage to bring features into focus on the screen. A digital counter on the stage reads X and Y position to micron resolution. The screen typically rotates and carries cross-hairs and a protractor scale for angle measurement.
Two illumination modes are standard. Contour (transmitted, back-lit) illumination shines light up from below the part — the projected image is a crisp dark silhouette on a bright background. This is the most common mode and is used for external profile, thread form, edge location, and dimensional inspection of any feature visible from the side. Surface (reflected, front-lit) illumination shines light down onto the part from above — the projected image shows the upper surface. This mode is used for inspecting print, scribed lines, recessed features, and the inside of holes or bores.
Profile projector vs optical comparator vs shadowgraph — terminology
There is no functional difference between a profile projector, an optical comparator, and a shadowgraph. The three terms refer to the same instrument and are used interchangeably in modern metrology. The naming reflects history rather than capability.
Shadowgraph is the oldest name, dating to the early 20th century when the instruments were used as comparison devices and the silhouette on the screen was literally referred to as the shadow of the part. Optical comparator became the dominant American name through the 1940s–1980s when the workflow was to compare the projected silhouette directly against a mylar overlay chart for go/no-go inspection. Profile projector is the modern technical name preferred by Mitutoyo (Japan), used in JIS B 7184:2021, and reflects the instrument's expansion from pure comparison to direct dimensional measurement via DRO.
Some manufacturers reserve "profile projector" for vertical benchtop models and "optical comparator" for horizontal floor-standing models, but this is a marketing convention rather than a technical distinction. Buyers should treat the three names as synonyms when shopping the AU market.
Profile projector vs vision measuring system vs CMM
A profile projector is the right tool when you need fast, low-cost, operator-driven 2D inspection of small parts. A vision measuring system delivers roughly twice the accuracy plus full automation but at three to five times the capital cost. A coordinate measuring machine measures 3D geometry and complex GD&T at the cost of slower throughput and longer setup. The three instruments overlap but each has a clear sweet spot.
| Criterion | Profile projector | Vision measuring system | CMM |
|---|---|---|---|
| Measurement dimension | 2D silhouette | 2D + limited 2.5D | Full 3D |
| Operator skill required | Moderate | Low (automated) | High (programming) |
| Throughput per part | Fast for simple 2D | Very fast (automated) | Slower |
| Accuracy (typical) | ±3–10 μm | ±1.5–5 μm | ±1–3 μm |
| Cost (capital) | Lowest | 3–5× projector | 5–20× projector |
| Best for | Quick 2D inspection, mylar overlay comparison, threads, gears, stampings | High-volume production QC, CAD overlay automation, complex 2D geometry | 3D geometry, GD&T verification, complex assemblies |
| Worst for | 3D features, blind holes, deep bores | Heavy production-floor environments, simple one-off measurement | Fast simple measurements, batch overlay comparison |
The Society of Manufacturing Engineers, Keyence, and Qualitest all reach the same conclusion: predictions of the optical comparator's obsolescence have been wrong since the 1920s. For 2D parts with quick changeovers — where programming a CMM might take longer than measuring the whole production run — the optical comparator remains the fastest and most cost-effective tool. Vision systems are taking share at the high-volume production end, but optical comparators continue to dominate toolroom and small-batch inspection.
Vertical vs horizontal profile projectors
Vertical profile projectors place the workpiece on a horizontal glass stage with the optical path going up through the part. Horizontal profile projectors place the workpiece on a vertical stage with the optical path going horizontally through the part. The orientation choice depends on workpiece weight, geometry, and — critically — whether thread inspection is part of the workload.
Use a vertical profile projector when you are inspecting small thin parts that sit flat on a glass stage — stamped sheet metal components, gaskets, small plastic mouldings, thin gears, cutting tool inserts, watch parts, electronic components. The Mitutoyo PJ-A3000 and PV-5110 are vertical models. Vertical projectors typically have smaller footprints and are easier to load.
Use a horizontal profile projector when you are inspecting longer or heavier parts that cannot sit flat — shafts, threaded rods, gears with significant face width, cutting tools held in collets, fasteners, larger machined components. The Mitutoyo PH-A14 and PH-3515F are horizontal models. Critical for thread inspection: the workstage on a horizontal projector has built-in helix angle adjustment (typically around 7°) so the stage can be tilted to align the light path straight across the thread flanks. Vertical projectors do not have this capability, so accurate thread profile inspection requires a horizontal unit.
Magnification options and view field
Profile projectors are supplied with one or more interchangeable projection lenses giving different magnifications. The Mitutoyo PJ-A3000 supports 10X (standard), 20X, 50X, and 100X — covering the full range from large parts down to fine features. Higher magnification gives a smaller view field but better feature resolution. Most workshops keep two or three lens choices on hand and swap between them depending on part size.
| Magnification | View field (PJ-A3000) | Typical applications |
|---|---|---|
| 10× (standard) | ø31.5 mm | Larger parts, overall profile, big stampings, plate features, getting started |
| 20× | ø15.7 mm | Medium features, gear teeth on small gears, thread root inspection, dimensional checks |
| 50× | ø6.3 mm | Small precision features, sharp corners, edge breaks, thread crest, fine geometry |
| 100× | ø3.1 mm | Very fine features, surface defects visible at edge, watch components, micro-machining |
Choosing magnification — the 10:1 Rule. The instrument's resolution should be approximately 10 times finer than the feature tolerance. For a feature with ±0.010 mm tolerance, the projected image should let you read to roughly ±0.001 mm — pick a magnification that gives clean visual separation at that scale. Over-magnifying makes features fuzzy at the edge of the field; under-magnifying makes fine features impossible to read accurately. This is the Test Uncertainty Ratio principle (TUR ≥ 10:1) widely adopted in quality metrology.
Contour vs surface illumination explained
Contour illumination (also called transmitted, back-lit, or silhouette illumination) is the default mode and produces a crisp dark image of the part outline on a bright screen. It is used for any feature visible from the side of the workpiece — external profile, thread form, holes that pass through, edge breaks, stamping outlines, gear teeth, broach shapes. The light source sits below the stage and the part blocks light to create the shadow.
Surface illumination (also called reflected, front-lit, or oblique illumination) shines light onto the workpiece from above and shows the upper surface in the projected image. It is used for inspecting print, scribed reference lines, recessed pockets, the bottom of blind holes (within the depth of field), and any feature that is visible from above but not from the side. The contrast in surface mode is much lower than contour mode — only certain surface finishes show clearly, and features need to be reasonably planar.
Practitioner reality: most inspection time on a profile projector is spent in contour mode. Surface illumination is used when contour mode cannot capture the feature — for example, when a depth-stamped marking needs to be read, or when a face-milled pocket geometry needs verification on an otherwise enclosed part. Both modes are standard on Mitutoyo's PJ-A3000 and PH-A14 ranges.
Mitutoyo profile projector range
Mitutoyo is the global benchmark in profile projectors. Their range spans benchtop vertical models for toolrooms through floor-standing horizontal models for production inspection, all built on telecentric optical systems with industry-standard 10X / 20X / 50X / 100X projection lens compatibility. AIMS supplies the Mitutoyo range across Australia.
| Model series | Type | Screen Ø | Stage travel | Best for |
|---|---|---|---|---|
| PJ-A3000 | Vertical benchtop | 315 mm | 50 × 50 mm to 100 × 100 mm | Toolroom workhorse, small thin parts, inserts, stampings, gaskets |
| PV-5110 | Vertical floor-standing | 510 mm | 200 × 100 mm and larger | Larger parts on a vertical stage, production inspection, batch QC |
| PH-A14 | Horizontal floor-standing | 356 mm | 150 × 75 mm | Threads (helix adjustment), shafts, cutting tools in collets, longer parts |
| PH-3515F | Horizontal floor-standing | 356 mm | 150 × 100 mm | Higher-accuracy horizontal inspection, fine quality work |
The PJ-A3000 is the volume seller for AU toolrooms. The PH-A14 is the workshop floor workhorse — Practical Machinist threads document units running reliably for over a decade with 10X and 20X lenses on the standard digital readout. The PV-5110 picks up where the PJ-A3000 runs out of stage travel. The PH-3515F is specified where accuracy demands push past the standard horizontal range.
All four Mitutoyo models share the QM-Data 200 data processing unit option (covered next) and accept the OptoEye optical edge detection accessory. All four use telecentric optics for distortion-free magnification. AIMS can supply, configure with the right lens combination, and arrange delivery with NATA-traceable calibration via approved AU partners.
QM-Data 200 digital readout and 2D data processor
The Mitutoyo QM-Data 200 is the standard 2D data processing unit for the PJ-A3000, PV-5110, PH-A14, and PH-3515F. It reads the X-Y stage encoders and the screen protractor, then calculates derived geometry — distance between points, angle between lines, intersection of lines, circle from three points, radius from arc, parallelism, perpendicularity — directly from probed reference points on the screen.
The QM-Data 200 is supplied in two mounting configurations: stand-mount (264-155A) sits on a separate stand next to the projector, and arm-mount (264-156A) mounts on a swing arm attached to the projector body. The arm-mount keeps the keypad close to the operator's working hand at the screen; the stand-mount frees the projector body for narrower bench installations.
Without the QM-Data 200, the projector still functions — the X-Y stage has its own digital counters and the screen has its own protractor — but the operator has to manually record points and calculate derived geometry off-line. With the QM-Data 200, geometry calculation, tolerance pass/fail, and data export to spreadsheet or SPC software become single-button operations. For any production inspection workload, the QM-Data 200 is effectively standard.
Edge detection — Mitutoyo OptoEye
Optical edge detection automates the moment of triggering a measurement. Without edge detection, the operator visually aligns a cross-hair on the screen against a feature edge and presses a button to capture the X-Y position. With edge detection, an optical sensor (the Mitutoyo OptoEye) detects the light-to-dark transition automatically as the stage moves through the feature, eliminating operator-induced trigger error.
The OptoEye is an optional accessory and is not required for the projector to function. Practitioner opinion on Practical Machinist is split. Some users describe edge detection as "need to have" — particularly in high-volume production where consistent inspector-independent results are critical. Others, including operators of the long-running PH-A14, report they "didn't bother with the fancy edge detection" because skilled visual alignment is faster on low-volume toolroom work where the operator already knows the feature being checked.
The rough decision rule: if production volume requires consistent results across multiple inspectors over a shift, specify the OptoEye. If a single skilled toolmaker is doing all the inspection and changeovers are frequent, the OptoEye is optional. Either way, the OptoEye can be added later — it is a screen-mounted sensor, not a base-instrument feature.
Mylar overlay charts — the traditional inspection workflow
A mylar overlay chart is a thin transparent polyester film printed with reference geometry — a radius template, an angle protractor, a thread profile, a gear tooth form, a grid — that the inspector clips to the projector screen over the projected silhouette. The visual alignment between the workpiece silhouette and the chart's reference geometry gives an immediate pass/fail comparison. This workflow predates digital readouts and remains widely used for go/no-go production inspection.
Standard overlay charts are stocked by metrology suppliers and cover common requirements: ISO and Whitworth thread forms, gear tooth profiles (involute, AGMA standards), radius templates from 0.5 mm to 50 mm, angle grids, toolmaker grids combining radius and angle in one chart. Suburban Tool, OGP, and VIP Charts are the dominant chart suppliers globally. Custom charts are manufactured to customer CAD drawings for proprietary geometry inspection — pricing typically scales with chart complexity and quantity.
Practitioner reality from VisionGauge and Practical Machinist: traditional mylar overlays are vulnerable to handling damage, require dedicated storage, can be misfiled in busy production environments, and need replacement whenever the part design changes. The modern alternative is digital CAD overlay — automated optical comparators (VisionGauge, OGP, Keyence IM-series) load CAD directly to the screen as a virtual overlay, eliminating physical chart storage and update costs. The hybrid workflow — physical mylar for established legacy products plus digital CAD for new designs — is common in larger AU toolrooms.
Accuracy and the JIS B 7184 framework
Profile projector accuracy is specified under the Japanese standard JIS B 7184:2021 — there is no equivalent ASME or ISO standard, so JIS B 7184 is the global reference. AU calibration laboratories reference JIS B 7184 when issuing traceable calibration certificates for profile projectors. The standard defines four metrological characteristics that together determine measurement accuracy.
| Characteristic | What it controls | Typical value (PJ-A3000) |
|---|---|---|
| Magnification accuracy — contour | Linear scale of measurements taken under transmitted illumination | ±0.08% of reading |
| Magnification accuracy — surface | Linear scale of measurements taken under reflected illumination | ±0.10% of reading |
| Length accuracy — X and Y axis | Stage encoder accuracy across the measurement travel | ±(3 + L/100) μm where L = travel in mm |
| Squareness accuracy | X-axis vs Y-axis perpendicularity, critical when measuring rectangular features | ±30 arc seconds (≈0.01 mm over 100 mm) |
For a workpiece feature measured under contour mode at 10X magnification with the stage moved 50 mm in X, the total measurement uncertainty is approximately the root-sum-square of magnification error (0.08% × measurement), length accuracy (3.5 μm), and a contribution from squareness when the feature is at an angle. The Mitutoyo educational document EDU-15002A gives worked examples of error stacking for buyer reference.
The 10:1 rule revisited. When selecting a profile projector for a particular tolerance, the instrument's measurement uncertainty should be approximately 10 times tighter than the tolerance. For a ±0.010 mm production tolerance, the projector and lens combination should be capable of ±0.001 mm at the relevant measurement scale. The PJ-A3000 with a 50X lens comfortably meets this on small features; tighter tolerances or larger parts may require the higher-accuracy PH-3515F.
Calibration and NATA accreditation in Australia
Profile projectors require periodic calibration to maintain accuracy traceable to national standards. The industry consensus calibration interval is 6 months for high-use production environments, 12 months for standard quality lab use, and up to 3 years for low-utilisation toolroom installations. AU calibration must be performed by a NATA-accredited laboratory if the certificate is required for ISO 9001, AS/NZS quality system audit, or regulated industry compliance (medical device, aerospace, automotive).
NATA-accredited profile projector calibration providers in Australia include the Optical Calibration Laboratory (NATA site 24605), Australian Metrology and Calibration Pty Ltd (NATA site 22230), and PCS Measurement. On-site calibration is the standard service — the calibrator brings master scales, certified gauge blocks, and reference angles to the workshop, performs verification across the four JIS B 7184 metrological characteristics, and issues a NATA-endorsed certificate.
Critical practical note: even moving a profile projector within a plant requires recalibration of the mirror mount. The first-surface mirror inside the projector sits in a precision mount, and any vibration or impact during a move can shift the optical alignment by enough to invalidate the calibration. Plan moves carefully — ideally schedule a recalibration immediately after any plant relocation. This caveat is documented in the Practical Machinist mirror cleaning thread and applies across all profile projector brands.
Common applications
Profile projectors are the inspection workhorse across a wide range of AU industries. The instrument suits any inspection task that involves small parts, 2D features, and visual or DRO-based dimensional verification. The non-contact nature is critical for soft or fragile parts that cannot tolerate contact-probe measurement.
- Cutting tools — drill point geometry, end mill flute profile, insert nose radius, broach tooth form, tap thread geometry (horizontal projector with helix adjustment).
- Threaded fasteners and machined threads — thread pitch, lead angle, flank angle, minor diameter, root radius. Horizontal projector mandatory. Overlay charts for common thread forms (ISO metric, UNC, UNF, BSP, ACME) standard.
- Gears — gear tooth profile, pressure angle, tooth thickness, module verification. Overlay charts for involute and AGMA forms available.
- Stamping and pressed parts — outline profile, hole position, bend radius, edge condition. Vertical projector typical.
- Plastic mouldings and rubber gaskets — non-contact essential because contact probes deform low-durometer materials. Profile projectors detect flash, sink marks, parting line errors, and warpage that callipers miss.
- Medical devices — stent geometry, catheter dimensions, implant features. FDA / TGA regulatory environments require traceable measurement, and profile projectors with NATA-calibrated certificates meet the requirement at low cost relative to vision systems.
- Electronics — PCB hole position, connector pin geometry, lead spacing, small component inspection.
- Watchmaking and micro-mechanical — fine features at 50X or 100X magnification.
- Reverse engineering — silhouette projection allows feature dimensions to be read from undocumented legacy parts.
Common mistakes and operator errors
Profile projectors are mechanically simple, but several recurring operator and maintenance errors degrade measurement accuracy or shorten instrument life. The list below is sourced from Practical Machinist threads, Mitutoyo educational materials, and AU calibration lab feedback.
| Mistake | Consequence | Fix |
|---|---|---|
| Cleaning the mirror with Windex and paper towels | Scratches the first-surface aluminium coating, scatters light, causes faint image and measurement error | Blow dust off with compressed air for precision optics first; only if necessary use cotton swab and clean alcohol, turning the swab each pass. Never paper towel |
| Touching the mirror with bare fingers | Oil deposits on first-surface coating, permanent staining, accelerated coating degradation | Never touch the mirror with anything other than approved cleaning materials. Wear gloves when accessing internal optics |
| Stage moved in wrong direction (reverse-image confusion) | New operator drives stage the wrong way, hits stop, jams encoder, misses feature | Mitutoyo projectors display reversed images (left-right and up-down). Train operators on the convention: image moves opposite to stage |
| Wrong magnification for the tolerance | Either over-magnified (features fuzzy at edge of field) or under-magnified (cannot resolve to required precision) | Apply 10:1 rule. Tolerance ±0.010 mm → instrument resolution ±0.001 mm → choose magnification giving clean visual separation at that scale |
| Surface illumination used when contour was needed | Low-contrast image, edge ambiguous, measurement uncertainty doubles | Default to contour (transmitted) for any external feature. Use surface only for upper-face features (print, recessed marking, blind hole bottom) |
| Thread inspection on vertical projector | Helix angle not compensated, thread image distorted, flank angle measurement wrong | Use a horizontal projector with helix adjustment for thread inspection. Vertical projectors are not suitable |
| Mylar overlay damaged or misfiled | Production stoppage while replacement is sourced or located | Establish a dedicated storage carousel for overlays. Number-code each chart. Photograph or scan each chart for reference |
| Missed calibration interval | Measurement uncertainty grows, quality records non-compliant, audit failure | Set 12-month recurring reminder. Schedule on-site NATA calibration. Keep certificate on file at the projector |
| Mirror mount not recalibrated after moving the unit | Optical alignment drift, screen image off-axis, measurement error | Recalibrate after any plant relocation, even within the same building |
| Operator uses wrong reticle or no reticle | Visual measurement error larger than projector capability | Use the screen cross-hairs and protractor scale consistently. For fast comparison, clip the appropriate mylar overlay |
Buying guide — new vs used, brand landscape
The profile projector market has a vibrant new-equipment segment dominated by Mitutoyo, Starrett, and Nikon, plus a deep used market where 20-to-40-year-old units from Mitutoyo, Nikon, J&L (Jones & Lamson), Scherr-Tumico, OGP, Suburban Tool, and Brown & Sharpe trade at prices well below new equivalents. For an AU buyer, the choice depends on accuracy requirements, calibration traceability needs, support availability, and budget.
| Tier | Brand | Position |
|---|---|---|
| Premium | Mitutoyo (Japan) | Global benchmark. AU support direct via Mitutoyo Australia and authorised resellers. Widest accessory range. Best resale value. |
| Premium | Nikon (Japan) | Microscope-grade optics. Strong on optical clarity at high magnification. Smaller AU presence than Mitutoyo. |
| Premium | Jones & Lamson / J&L (USA) | "The cadillac price" per Practical Machinist consensus. Heavy floor-standing units. Strong used market. |
| Mid | Starrett (USA — HE400 horizontal) | AU best-seller via Met Optix ANZ partnership since 2014. Workhorse benchtop. Good service network. |
| Mid | Suburban Tool (USA — Master-View 14") | Solid mid-range American optical comparator. Mylar overlay specialist. |
| Mid | Brown & Sharpe | Legacy American name. Most current sales are used / refurbished. |
| Legacy / used | Scherr-Tumico, Micro-Vu, OGP / Focus, Westinghouse | Heavy used-market presence. A well-maintained 30-year-old Mitutoyo PH-350 in good optical condition will out-perform most new budget imports. |
| Modern automated | VisionGauge, OGP SmartScope, Keyence IM-series | Automated optical comparators (AOC) and vision systems with digital CAD overlay. Replace mylar workflow. Higher capital cost. |
Buying used — what to inspect. Optics first: check the first-surface mirror for scratches (any visible damage scatters light and causes faint screen image). Check the projection lens for cleanliness and chips. Test all available magnifications. Confirm the screen rotates smoothly and protractor scale is undamaged. Test stage X-Y travel through the full range, check for backlash and binding. Verify the digital readout reads consistently. If the unit has OptoEye edge detection, test it across light-to-dark transitions. Most used Mitutoyo units that pass these checks have 20+ years of remaining service life.
Two big maintenance cost factors on used units: replacement lenses (if a different magnification is needed) and mirror recoating (if the original coating is scratched or oxidised). On the oldest legacy units, the projector bulb itself can be a sourcing challenge — some 1970s units use bulbs originally manufactured for cinema projectors that are no longer in production. LED retrofit kits exist for many older Mitutoyo and Nikon units and significantly extend service life.
Lead times, configuration, and AIMS supply
AIMS Industrial supplies the Mitutoyo profile projector range across Australia, including the PJ-A3000 vertical benchtop, PV-5110 vertical floor-standing, PH-A14 horizontal floor-standing, and PH-3515F higher-accuracy horizontal. We can configure each unit with the right combination of projection lenses (10X / 20X / 50X / 100X), the QM-Data 200 digital readout in stand-mount or arm-mount configuration, the OptoEye optical edge detection accessory, and the supporting accessories (workpiece fixtures, surface plate base, lens cleaning kits).
Lead times depend on configuration and current Mitutoyo Australia stock holdings. Stock configurations typically ship within 2–4 weeks; custom configurations (specific lens combinations, OptoEye factory integration, regional voltage variants) typically run 6–12 weeks. AIMS coordinates delivery, installation, operator training, and NATA-traceable calibration via approved AU partners.
For specific pricing, current lead time on a particular configuration, or for advice on which Mitutoyo model best fits an application, contact our team. We can also quote on used Mitutoyo units sourced through Mitutoyo Australia's certified pre-owned channel, where availability allows. AIMS supplies adjacent metrology kit — gauge blocks, surface plates, dial indicators, micrometers, calibration standards — that typically accompanies a profile projector installation.
Looking to invest in a profile projector?
AIMS Industrial supplies Mitutoyo profile projectors and optical comparators across Australia. Whether you're after a benchtop PJ-A3000 for a toolroom, a floor-standing PH-A14 for production inspection, or a higher-accuracy PH-3515F for fine quality work — we can quote, configure with the right magnification options, and arrange delivery with NATA-traceable calibration.
Call (02) 9773 0122 or contact our team for current pricing and lead times.
Frequently Asked Questions
What is a profile projector used for?
A profile projector is used to inspect the 2D silhouette of small parts at high magnification — typically 10X to 100X — for dimensional verification, thread inspection, gear tooth profile checking, stamping outline verification, and quality control on plastic mouldings, rubber gaskets, and small machined parts. It is also called an optical comparator or shadowgraph and is one of the most common metrology instruments in AU toolrooms and inspection labs.
What is the difference between a profile projector and an optical comparator?
There is no functional difference — profile projector, optical comparator, and shadowgraph are three names for the same instrument. The name varies by region and history. Mitutoyo and most modern manufacturers use "profile projector"; American manufacturers and older literature often use "optical comparator"; "shadowgraph" is the original early-20th-century name reflecting the silhouette-on-screen physics.
What is the difference between a profile projector and a vision measuring system?
A profile projector uses an optical-only system — light, mirrors, lens, screen — with operator-driven measurement against cross-hairs or mylar overlays. A vision measuring system uses a camera-based digital system with automated CAD overlay, image processing, and computer-controlled stage movement. Vision systems offer roughly twice the accuracy and full automation at three to five times the capital cost. Profile projectors win on simplicity, speed for 2D parts, and total cost of ownership.
How does an optical comparator work?
Light from a source passes the workpiece on a glass stage, through a telecentric projection lens, off one or more mirrors, and onto a translucent screen — projecting a magnified silhouette. The operator moves the stage to bring features into focus and reads X-Y position from digital counters on the stage, plus angle from a protractor scale on the rotating screen. With a digital readout (Mitutoyo QM-Data 200), derived geometry — distance, angle, intersection, radius — is calculated automatically from probed reference points.
Why is the image reversed on a profile projector?
The image is reversed (left-right and up-down inverted) because adding the extra mirrors needed to right the image would require more optical path length than fits in the projector housing. All major Mitutoyo profile projectors display reversed images — this is a deliberate design trade-off that keeps the instrument compact and affordable. New operators need brief training: when you move the stage right, the image appears to move left, and vice versa.
What is JIS B 7184?
JIS B 7184 is the Japanese Industrial Standard for profile projectors, most recently updated as JIS B 7184:2021. Because no equivalent ASME, ANSI, or ISO standard exists for profile projectors, JIS B 7184 is the global reference document for profile projector accuracy specification. It defines four key metrological characteristics: magnification accuracy under contour illumination, magnification accuracy under surface illumination, length accuracy on the X and Y axes, and squareness accuracy between X and Y axes.
What is the calibration interval for a profile projector?
The calibration interval depends on use intensity. Industry consensus is 6 months for high-use production inspection, 12 months for standard quality lab use, and up to 3 years for low-utilisation toolroom installations. In Australia, calibration should be performed by a NATA-accredited laboratory (Optical Calibration Laboratory, Australian Metrology and Calibration, PCS Measurement) if the certificate is required for ISO 9001, AS/NZS quality system audit, medical device, aerospace, or automotive compliance.
What is a mylar overlay chart?
A mylar overlay is a thin transparent polyester film printed with reference geometry — radius templates, angle protractors, thread profiles, gear tooth forms, grids — that is clipped to the projector screen for visual comparison with the workpiece silhouette. Standard charts cover ISO and Whitworth thread forms, gear involute profiles, radii from 0.5 mm to 50 mm, and toolmaker grids. Custom charts are manufactured to customer CAD drawings for proprietary geometry inspection.
Can a profile projector measure 3D features?
No — profile projectors measure only the 2D silhouette of a feature as seen from the optical axis. They cannot measure depth, blind hole bottoms (beyond the depth of field), or true 3D geometry. For 3D inspection, use a coordinate measuring machine (CMM). The 2D limitation is a deliberate trade-off — it is precisely what makes profile projectors fast, low-cost, and easy to operate compared to CMMs.
What is contour illumination vs surface illumination?
Contour illumination (transmitted or back-lit) shines light up from below the workpiece — projecting a dark silhouette on a bright screen. This is the most common mode and is used for external profile, thread form, and edge inspection. Surface illumination (reflected or front-lit) shines light down onto the workpiece from above — showing the upper surface in the projected image. Surface mode is used for inspecting print, scribed lines, recessed pockets, and blind features.
What magnification should I use?
Apply the 10:1 Rule (Test Uncertainty Ratio): the instrument's measurement resolution should be approximately 10 times tighter than the feature tolerance. For a ±0.010 mm tolerance, the projected image should let you read to roughly ±0.001 mm — pick a magnification that gives clean visual separation at that scale. Most AU toolrooms keep 10X (standard), 20X, and 50X lenses on hand and swap between them depending on the feature. 100X is reserved for very fine features.
Is a horizontal or vertical profile projector better for thread inspection?
A horizontal profile projector is required for accurate thread inspection. The workstage on a horizontal model has built-in helix angle adjustment (typically around 7°), allowing the stage to be tilted so the light path passes straight across the thread flanks. Vertical projectors do not have helix capability, so the projected image of a thread is distorted by the helix angle and flank measurement is inaccurate. The Mitutoyo PH-A14 is the standard AU choice for thread inspection.
How do I clean the mirrors in an optical comparator?
Profile projector internal mirrors are first-surface mirrors — the reflective aluminium coating is on the front, not behind glass — and are easily damaged by abrasive cleaning. The safe protocol is: first, blow dust off with compressed gas sold for precision optics; second, if smudges remain, use a clean cotton swab dampened with clean alcohol, turning the swab each pass to avoid dragging dust across the surface. Never use Windex, paper towels, or pressure. If the coating is already scratched, the mirror can be stripped, re-aluminised, and given a silicon monoxide overcoat by specialist optical repair services.
Is the optical comparator obsolete?
No. The optical comparator's demise has been predicted since the 1920s and has not happened. The instrument continues to dominate toolroom and small-batch 2D inspection because it is cost-effective, fast for the right job, low-skill to operate after brief training, and rugged for shop-floor environments. Vision measuring systems and CMMs have taken share at the high-volume production and 3D inspection ends respectively, but the profile projector remains the right tool for 2D feature inspection where speed and cost matter more than full 3D capability.
Does AIMS supply Mitutoyo profile projectors in Australia?
Yes. AIMS Industrial supplies the full Mitutoyo profile projector range across Australia — PJ-A3000 vertical benchtop, PV-5110 vertical floor-standing, PH-A14 horizontal floor-standing, and PH-3515F higher-accuracy horizontal — configured with the right lens combination (10X / 20X / 50X / 100X), QM-Data 200 digital readout, OptoEye edge detection where required, and supporting accessories. We coordinate delivery, installation, operator training, and NATA-traceable calibration via approved AU partners. Contact our team on (02) 9773 0122 for pricing and current lead times.
Cross-reference our GD&T Symbols Guide for flatness, perpendicularity, concentricity, parallelism and more.
