Overview

Stainless steel aperture etching forms optical stops, pinholes and diaphragm leaves by dissolving the opening out of thin 304/316L stainless, nickel or invar sheet, so the edge is sharp, round and free of the burr or taper that a drilled or punched hole leaves behind. A resist mask is imaged on both faces, developed, and metal is removed from each side until the aperture breaks through with a clean, near-vertical wall. Stock from 0.02 mm to 0.5 mm is common, with hole diameter held to about ±0.005 mm, hole position to ±0.01 mm, minimum openings near 0.03 mm and roundness within ±0.003 mm. Because the geometry is set by artwork, a multi-hole mask, a slit array or a set of graduated stops is produced in one pass without hard tooling.

For optical and instrument buyers, stainless steel aperture etching is about controlling stray light. A drilled hole carries tool marks and a bell-mouth that scatter the beam, and a punched opening drifts in diameter across a batch, which shifts the f-number or the field stop. Photochemical machining keeps diameter, roundness and position uniform from the first sheet to the thousandth, so the transmitted wavefront and the light-tight boundary stay repeatable. Blackening, electropolishing or a matte finish can be added to suppress reflections, and several apertures with different diameters can sit on one substrate for a compact optical stack.

Parameter Window

• Available Materials: 304/316L stainless steel, nickel, invar alloy
• Material Thickness Range: 0.02–0.5 mm
• Tolerance: ±0.005 mm on hole diameter, ±0.01 mm on hole position
• Minimum Feature: 0.03 mm aperture, roundness within ±0.003 mm
• Surface Options: black oxide, electropolishing, nickel plating, matte anti-reflection finish
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork Review — Verify aperture diameter, roundness, pitch and edge break against stock thickness, and confirm the blackening requirement.
2. Material Selection — Choose 304 for general optics, nickel for fine grain, or invar where thermal stability of the opening matters.
3. Cleaning & Lamination — Degrease and laminate dry-film resist to both faces so the aperture etches symmetrically.
4. Dual-side Exposure — Register front and back patterns so the opening meets mid-thickness with a straight, round wall.
5. Development — Wash out unexposed resist and inspect tiny openings for scumming or residue before etching.
6. Etching — Spray chemistry matched to the alloy; time and speed control final diameter, roundness and wall verticality.
7. Stripping & Finishing — Remove resist, neutralize, then blacken, electropolish or apply a matte anti-reflection finish.
8. Inspection & Packaging — Measure diameter, roundness and position optically against the approved sample, then pack in clean trays.

Core Advantages

1. Optically clean edges: Chemical removal leaves no tool marks or bell-mouth, so the aperture scatters far less stray light.
2. Tight diameter control: Hole diameter held to ±0.005 mm keeps f-number and field stop repeatable across a batch.
3. True roundness: Roundness within ±0.003 mm protects beam symmetry in imaging and laser systems.
4. Bur-free micro-openings: Openings down to 0.03 mm stay open and clean without drill wander or punch burrs.
5. Low tooling cost: A new aperture set is a new film, making custom pinhole arrays and prototypes economical.
6. Multi-aperture integration: Stainless steel aperture etching can place graduated stops, slits and alignment holes on one substrate in a single pass.

Typical Applications

• Microscope and camera stops: Precision diaphragms that set the numerical aperture without edge glare.
• Laser pinholes: Round, clean spatial filters for beam cleanup and alignment.
• Encoder and code masks: Aperture arrays with repeatable position for optical encoders.
• Shutter and diaphragm leaves: Thin, flat leaves with clean edges for exposure mechanisms.
• Electron-beam and deposition masks: Micro-openings used as shadow masks in thin-film work.
• Sensor field stops: Light-tight apertures that define the detector field of view.

Design Notes & Process Considerations

1. Diameter versus thickness: Keep the opening at no less than 1.2 × stock thickness, or aspect ratio will distort roundness.
2. Roundness callout: State roundness and diameter tolerance together, and note whether they are measured before or after finishing.
3. Edge and wall: Specify wall verticality and any edge break; a bell-mouth on one face will scatter light asymmetrically.
4. Anti-reflection finish: Name the blackening or matte system and confirm it does not shrink the clear aperture.
5. Flatness: Call out flatness per 100 mm when the stop is clamped in an optical stack.
6. Substrate layout: Stainless steel aperture etching benefits from grouping graduated stops on one sheet with shared datums to protect hole position.