Overview

Stainless steel grating etching is the photochemical route to making precision slit and line arrays for optical encoders, spectrometers, masks and alignment targets. A photoresist carrying the grating pattern is exposed on thin stainless sheet, developed, and a tightly controlled etchant opens the lines or slots from both faces, producing crisp, burr-free rulings with a uniform pitch. Because the pattern is defined by a photo-tool rather than a ruling engine or a stamping die, line width, pitch and duty cycle are set by the artwork and repeat exactly across the whole panel. Stainless 304/316L is the standard substrate, with Invar used where thermal expansion must be minimal; stock typically runs from 0.05 mm to 0.5 mm.

For optical and motion-control engineers, stainless steel grating etching delivers geometry that mechanical ruling and weaving cannot: lines down to 0.02 mm on 0.05 mm pitch hold ±0.005 mm, edges are straight and free of the burr that scatters light, and the flat, stress-free sheet stays dimensionally stable through temperature swings. A grating with thousands of identical lines, an index mark and a mounting frame can be produced in one etching cycle without cumulative tool error. The film-only tooling also makes custom pitch, code patterns and prototype runs economical, which suits encoder discs, reticles and calibration standards.

Parameter Window

• Available Materials: 304/316L stainless steel, Invar, copper, nickel on request
• Material Thickness Range: 0.05–0.5 mm
• Tolerance: ±0.005 mm on line width and pitch, ±0.01 mm on absolute position
• Minimum Feature: 0.02 mm line width, 0.05 mm pitch, 0.03 mm slot, duty cycle held per drawing
• Surface Options: blackened, matte anti-glare, mirror, burr-free, stress-relieved, etched index marks
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Pattern Review — Confirm line width, pitch, duty cycle, index marks and frame geometry against the optical design.
2. Material Selection — Choose 304/316L for general use, Invar for low thermal expansion, copper for reflective gratings.
3. Cleaning & Lamination — Degrease and laminate a thin, high-resolution dry-film resist under tightly controlled conditions.
4. High-Resolution Exposure — Expose the grating film with collimated UV and registered fiducials to hold pitch across the panel.
5. Development — Open the line areas and inspect for resist bridging or line-width loss at microscope level.
6. Etching — Spray etchant from both faces, using short, precisely timed cycles to hold fine line width and straight walls.
7. Stripping & Finishing — Strip resist, then blacken, matte or mirror finish and stress-relieve for dimensional stability.
8. Inspection & Packaging — Verify pitch, line width and position by vision or microscope, then pack flat with lot records.

Core Advantages

1. Sub-0.05 mm pitch: Line and slot geometry holds at 0.02 mm line width, beyond the reach of stamping.
2. Burr-free optical edges: Chemical lines have no raised lip, so light scatter and stray reflection stay low.
3. No cumulative error: All rulings come from one photo-tool, avoiding the drift of a mechanical ruling engine.
4. Flat and stable: Stress-free sheet keeps pitch and position steady over temperature and through bonding.
5. Patterns plus frame in one part: Grating, index mark and mounting outline are etched together in a single cycle.
6. Material and code flexibility: Stainless steel grating etching can run stainless, Invar or copper and carry custom codes, reference marks and logos without hard tooling.

Typical Applications

• Optical encoder discs and strips: Fine-pitch line arrays for rotary and linear position feedback.
• Spectrometer slits and reticles: Precision entrance slits, masks and calibration targets.
• Alignment and calibration standards: Grid and ruler patterns for machine-vision setup.
• Moire and displacement screens: Paired gratings for strain and motion measurement.
• EMI and optical shielding meshes: Dense line arrays that double as functional apertures.
• Diffraction and education parts: Custom pitch gratings for lab and teaching optics.

Design Notes & Process Considerations

1. Pitch and duty cycle: Specify line width, pitch and duty cycle together; one value alone does not define the grating.
2. Line width versus thickness: Keep line width realistic for the stock — 0.02 mm calls for thin foil and tight process control.
3. Edge straightness: Call out edge roughness or straightness where scattered light affects signal contrast.
4. Surface finish: Choose blackened or matte for low reflection, mirror for reflective gratings, and state the gloss target.
5. Thermal stability: Note operating temperature range and consider Invar when pitch drift must be minimized.
6. Panel layout: Nest gratings with shared fiducials and keep the active area away from the sheet edge undercut.