Overview

An aperture plate is a thin metal disc or foil carrying one or more precision apertures placed in front of a lens, light source or detector to limit the beam, block stray light and define the field of view. What makes it an optical part rather than a simple punched washer is the hole wall: the rim must be round and burr-free, the wall nearly vertical, and the diameter held to micrometre level, otherwise edge diffraction and reflection degrade the image. Photochemical etching images the aperture array onto stainless steel or nickel foil from high-resolution film and etches both faces together to control taper; where an ultra-thin, near-zero-taper or integrally blackened part is needed, precision electroforming deposits nickel onto a mandrel and releases a stress-free foil.

An OEM aperture plate is built to the customer optical drawing rather than a catalogue size: aperture diameter, count, pitch, outer diameter and mounting holes all follow the print, and one film reproduces identically from first article to volume. Typical stock is 304/316L stainless steel, nickel or Kovar between 0.02 mm and 1.0 mm, with optical-grade diameter tolerance to ±0.005 mm and pinholes down to 0.02 mm. These plates serve cameras, microscopes, spectrometers, particle counters and encoder modules, supplied as loose foils or framed parts with measured aperture and position data. Prototype turnaround is short because a change is only a new film, which suits the frequent revisions of optical programs.

Parameter Window

• Available Materials: 304/316L stainless steel, nickel, copper, Kovar, blackened nickel
• Material Thickness Range: 0.02–1.0 mm (optical grades commonly 0.05–0.3 mm)
• Tolerance: ±0.005 mm on aperture diameter (optical grade), ±0.01 mm on position
• Minimum Feature: 0.02 mm pinhole, 0.03 mm slit
• Surface Options: black oxide, matte anti-reflection, Ni plating, passivation, anodic blackening
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork & DFM Review — Convert the optical drawing into vector artwork and check aperture, pitch and rim margin against thickness and thickness-to-hole ratio.
2. Material Selection — Choose 304/316L, nickel or Kovar for the required blackening and corrosion behaviour, then confirm flatness before lamination.
3. Cleaning & Lamination — Degrease and laminate dry-film photoresist on both faces under controlled heat and pressure.
4. UV Exposure — Expose the aperture array on both faces through registered high-resolution film so the two sides align without wall skew.
5. Development — Wash out unexposed resist to open every aperture, then inspect the finest pinholes for residue.
6. Controlled Etching — Spray both faces with etchant matched to the alloy, holding diameter and wall taper through time, temperature and conveyor speed.
7. Stripping & Finishing — Remove resist, neutralize, then blacken, matte-treat or Ni-plate, keeping optical faces free of fingerprints and residue.
8. Inspection & Packaging — Measure every aperture and position with a vision system against the approved first article, then pack on liner or in light-safe trays.

Core Advantages

1. Clean rims: Chemical or electrochemical formation leaves round, burr-free edges, so edge diffraction is low and image contrast stays stable.
2. Micrometre repeatability: Diameter and position come from one double-sided artwork, so the whole lot and multi-pinhole arrays stay consistent without per-part calibration.
3. Vertical walls: Double-side etching or electroforming holds taper very small, giving a near-vertical light channel even on thicker stock.
4. Built-in blackening: Matte and black-oxide finishes are part of the part, not a sprayed layer, so they do not flake or change diameter with wiping.
5. Cheap revisions: A new diameter or pattern is only a new film, which suits frequent optical iterations and small pilot runs.
6. Drawing-matched supply: Round holes, slits, pinhole arrays and shaped outlines are all built to print, with foil or framed delivery — what an OEM aperture plate program needs.

Typical Applications

• Cameras and lenses: Fixed stops and stray-light baffles in front of the iris with round, low-reflection rims.
• Microscopes: Field stops for objectives and condensers with stable diameter and non-reflective edges.
• Spectrometers: Entrance and exit slit plates with micrometre slit width and vertical light channels.
• Particle counters: Pinhole arrays for flow and dust counters with even, equally spaced holes.
• Optical encoders: Aperture masks for encoder modules with precise position and good repeatability.
• Laser and sensing: Beam-shaping and detector-limiting plates that hold diameter over long service.

Design Notes & Process Considerations

1. Diameter versus thickness: Calculate the smallest hole together with stock thickness; too small a hole in thick stock etches a visible taper.
2. Complete callouts: Give diameter tolerance, position tolerance and roundness, not just diameter, or dense arrays shift as a group.
3. Wall and taper: State wall verticality and taper direction, since double-side misregistration skews the light path and distorts the spot.
4. Surface and cleanliness: Name the blackening process and reflectance target, and require optical faces free of fingerprints, residue and scratches with light-safe packing.
5. Rim and mounting: Give the solid outer rim and mounting-hole positions so assembly never presses on the aperture zone or lets light leak past the edge.
6. Panelization: Group several diameters on one sheet with shared registration marks to cut handling cost on repeat OEM aperture plate orders.