Overview

Micro aperture etching produces pinholes, slits and diaphragms whose value lies in the quality of the knife edge rather than in the outline of the part. Fine-grain dry film is laminated to both faces of thin foil, a high-resolution chrome mask defines the hole, and balanced two-sided etching makes the two cutting fronts meet at mid-thickness, leaving a sharp, burr-free land with no roll-over. Materials are usually 304/316L stainless, nickel 200, molybdenum, C17200 beryllium copper, brass or Alloy 42, at 0.02–0.5 mm; knife-edge parts typically use 0.02–0.10 mm. The short edge land on thin foil lets light pass without wall reflection or vignetting, something punching and drilling cannot achieve.

For a buyer, micro aperture etching is chosen when diameter, roundness and edge acuity must all be held at once. Diameter holds to ±0.005 mm with near-ideal roundness, so diffraction spots and flux stay calibrated, while even a tiny burr or rolled edge becomes a stray-light source under dark-field illumination and lowers image contrast. Balanced two-sided etching places the knife edge at mid-thickness, and black oxide, black nickel or black PVD suppresses reflections right up to the hole without bridging a 0.01 mm opening. Multi-hole and slit arrays share one mask, so consistency across a sheet is far better than hole-by-hole machining.

Parameter Window

• Available Materials: 304/316L stainless, nickel 200, molybdenum, beryllium copper C17200, brass, Alloy 42
• Material Thickness Range: 0.02–0.5 mm (knife-edge parts usually 0.02–0.10 mm)
• Tolerance: ±0.005 mm on hole diameter; ±0.01 mm on concentricity; roundness within 0.005 mm
• Minimum Feature: 0.01 mm pinhole on 0.02 mm foil; slit width 0.02 mm; knife-edge land below 0.01 mm
• Surface Options: black oxide, black nickel, ebonized, matte black PVD, passivated, anti-reflection coating
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Optical Requirement Review — Confirm diameter, roundness, edge acuity and stray-light limits before artwork.
2. Thin-Gauge Selection — Choose 0.02–0.10 mm nickel, stainless or molybdenum to keep the edge land short.
3. Cleaning & Lamination — Laminate fine-grain dry film to both faces without trapping dust at the pinhole site.
4. High-Resolution Exposure — Expose through a glass/chrome mask registered to the optical datum.
5. Development — Open the pinhole and check for resist scum that would round the edge.
6. Balanced Two-Sided Etching — Etch from both faces so the knife edge forms at mid-thickness with no burr or roll-over.
7. Blackening & Stripping — Strip, then black-oxide, black-nickel or PVD-coat to suppress reflections at the edge.
8. Optical Inspection — Measure diameter and roundness by backlit vision and inspect the knife edge under dark-field microscopy.

Core Advantages

1. True knife edge: Balanced two-sided etching meets at mid-thickness, leaving a sharp land with no burr or roll-over to scatter light.
2. Tight diameter & roundness: Holds ±0.005 mm and near-perfect roundness, so the diffraction pattern and flux stay calibrated.
3. No mechanical stress: No punching or drilling force, so thin molybdenum or nickel foils stay flat and un-distorted.
4. Clean stray-light control: Blackening can be applied right up to the edge without bridging or closing a 0.01 mm hole.
5. Repeatable arrays: Multi-aperture and slit patterns repeat identically across a sheet for camera and sensor calibration.
6. Material choice for optics: Molybdenum for low glare, nickel for fine grain, 316L for corrosion — all run on one line.

Typical Applications

• Pinhole cameras & optics: Calibrated micro-pinholes for imaging, alignment and diffraction work.
• Confocal & microscope apertures: Spinning-disc and field-stop apertures where edge quality sets contrast.
• Spectrometer slits: Precision entrance and exit slits with straight, burr-free knife edges.
• Laser beam shaping: Spatial filters and mode-cleaning apertures in molybdenum or nickel.
• Sensor calibration targets: Roundness and diameter standards for machine-vision and photometry.
• Analytical instruments: Stray-light baffles and apertures with blackened edges for detectors and analyzers.

Design Notes & Process Considerations

1. Edge acuity first: Specify the knife-edge land and forbid burr or roll-over explicitly; a rounded edge raises stray light.
2. Diameter versus thickness: Keep hole diameter ≥ 0.5 × thickness for a clean knife edge, or switch to a thinner foil.
3. Roundness & concentricity: Call out both to the optical datum; drilling and punching cannot hold them at this scale.
4. Blackening thickness: State the coating and its maximum build-up; a heavy black layer can shrink a 0.01 mm hole measurably.
5. Handling & cleanliness: Require cleanroom packing and edge protection — one dust particle or nick ruins the aperture.
6. Array registration: For multi-hole parts, remember micro aperture etching defines all holes from one mask, so shared datums are essential.