Published July 12, 2026 at 07:35
A quality lab needs to verify the depth of laser-engraved markings on a medical implant. The requirement: 0.05 ± 0.01 mm deep. Too shallow = the engraving becomes illegible after short-term use. Too deep = structural weakening of the implant.
How do you measure a 50-micrometer depth without cutting up the workpiece? A micrometer with a sharp point cannot reach into the 0.3 mm wide groove. A dial indicator does not fit. A 3D scanner yields usable results but costs 500,000+ SEK. A coordinate measuring machine can measure it, but takes 15–20 minutes per point.
The Peak 2034-CIL-300-ZX depth measuring microscope solves this using an ingenious optical principle: OPTICAL SECTIONING. With 300x magnification, the instrument’s depth of field is only a few micrometers. By focusing first on the SURFACE, then on the BOTTOM, and reading the difference on the Z-axis, the operator obtains the depth with 1 μm precision.
Optical sectioning: the principle behind it
At low magnification (5–20x), microscopes have a large depth of field — several millimeters can be ”in focus” simultaneously. At high magnification, the depth of field decreases dramatically:
- 10x: depth of field ~1 mm.
- 50x: depth of field ~50 μm.
- 100x: depth of field ~10 μm.
- 300x: depth of field ~2–3 μm.
- 1000x: depth of field ~0.2 μm.
At 300x, only ONE narrow height layer of the object can be sharp. Above and below, objects are BLURRED. This is normally a DISADVANTAGE — you typically want to see a 3D object in focus throughout. But for DEPTH MEASUREMENT, it is an advantage: by moving the optics (or the object) along the Z-axis and observing WHICH HEIGHT is in focus, you can build a Z-map of the object’s surfaces.
The 2034-CIL-300-ZX workflow:
- Place the workpiece under the microscope.
- Focus the microscope on the top surface around the groove. Note the Z-position on the focusing knob (scale with 1 μm graduations).
- Screw the microscope down to focus on the BOTTOM of the groove. Note the new Z-position.
- Difference between the two Z-positions = depth of the groove.
2034-CIL-300-ZX construction
This instrument is an OPTICAL MICROMETER — not a standard microscope with Z-manipulation. The construction is specially adapted for Z-precision:
- Stabilized microscope body: The 2034 series is designed for Z-direction stability. Standard microscopes typically have 5–10 μm Z-drift during operation; the depth measuring version has under 1 μm drift.
- 30x objective: Provides 300x total magnification with a 10x eyepiece. The optical quality is high: zero distortion, corrected chromatic aberration.
- Coaxial through-the-lens illumination: The light travels FORWARD along the same path the eye looks through. This provides the best contrast for identifying the focal plane position.
- Fine-focus mechanism: 1 μm graduations on the focusing knob. Precision thread with minimal backlash.
- Can be shifted aside for rapid adjustment: During coarse positioning, the knob moves freely; for fine measurement, the micrometer mechanism is engaged.
Eyepiece reticle scale
In addition to Z-measurement, the instrument is also a LATERAL measuring microscope. The eyepiece features an integrated glass reticle with:
- Smallest graduation: 1 μm.
- Scale length: 0.2 mm.
- Field of view: 0.48 mm.
Thus, the operator can measure both depth (via Z-focus difference) AND lateral dimensions (via the eyepiece scale) using the same instrument.
Focus direction: a critical detail
The single most important technique in depth measurement: ALWAYS FOCUS FROM THE SAME DIRECTION. Screw down to focus on the top; screw DOWN FURTHER to focus on the bottom. Never screw UP between measurements.
The reason: the precision thread has microscopic BACKLASH — a deadband of 1–3 μm between knob rotation and Z-movement. If the operator turns down for the top, then up and down again for the bottom, backlash errors accumulate and are directly added to the depth measurement.
Proper technique:
- Coarse-focus in side-shift mode.
- Engage the fine mechanism. Focus on the top by SCREWING DOWN from an OUT-OF-FOCUS position.
- Note Z_top.
- Continue screwing DOWN until the bottom is sharp.
- Note Z_bottom.
- Depth = Z_bottom − Z_top.
Never back up between the two focal points. If you suspect an error — start over from the coarse-focus state.
The MST stand: an essential accessory
The instrument is delivered with the MST stand, which provides secure positioning on:
- Cylindrical workpieces (rollers, tubes, shafts).
- Flat materials (sheet metal, boards, panels).
The MST has three contact points — two at the base (rollable on cylindrical surfaces) and one at the top of the instrument. This triangular setup allows the workpiece to be rotated for measurement at different lateral positions without needing to move the instrument.
Additional accessories (cross table 25×25 mm + rotation stage) are available for XY positioning of workpieces.
Five-millimeter X-adjustment
At 300x magnification and a 0.48 mm field of view, the operator sees very little of the workpiece at any one time. To inspect different parts of a larger workpiece, XY manipulation is required.
The 2034-CIL-300-ZX features a built-in 5 mm X-adjustment — the instrument head can be slid 5 mm in the X-direction without moving the stand or the workpiece. This is sufficient to inspect 5 mm long groove engravings or multiple markings located side by side in a batch.
Common applications
Laser engraving depth measurement: Medical implants, tool markings, security stamps.
Etching and sheet metal processing: PCB etching depth, chemical milling depth.
Tool wear measurement: Wear pits in cutting tools, chip grooves in piston rings.
Surface defect analysis: Depth of pitting corrosion pits, corrosion depth, cracks.
Collectibles verification: Postage stamp perforation height, coin relief depth.
Seal inspection: Depth of stamp impressions on metal, plastic, paper.
Philatelic analysis: Paper perforation depth for security verification.
Sub-surface measurement on transparent materials: Measuring the depth of embedded defects in glass or transparent plastic.
What the instrument CANNOT do
- Digital camera connection: Explicitly stated in the product description — combination with digital camera measurement functionality is not possible. This is a purely optical instrument, with readouts taken through the eyepiece.
- Continuous 3D scanning: Only measures selected points, not entire surfaces. Full topography requires a 3D microscope (typically 200,000+ SEK).
- Depths over 5–10 mm: The movement range of the focusing mechanism is limited.
- Very small depths (under 0.5 μm): Below the focal plane resolution limit. An interferometer is required.
What you get for your money
Peak 2034-CIL-300-ZX depth measuring microscope, 300x total magnification (30x objective + 10x eyepiece), 1 μm-graduated eyepiece scale with 0.2 mm scale length, 0.48 mm field of view, coaxial through-the-lens illumination, stabilized microscope body for Z-direction precision, fine-focus mechanism with 1 μm graduations and slide-shift rapid adjustment, 5 mm built-in X-adjustment, MST stand for positioning on cylindrical or flat workpieces. 54,878 SEK.
A specialized tool for tool quality labs, medical technology manufacturing, PCB processing, and other applications where the depth of engravings, etchings, markings, or surface defects must be measured with micrometer precision without destructive analysis. For daily depth measurement needs, this optical micrometer is a significant investment that delivers faster and more flexible measurements than alternative methods (coordinate measuring machines, 3D scanning). For occasional depth measurements, simpler instruments will suffice.
Read more: Peak 2034-CIL-300-ZX depth measuring microscope in the shop →
