Circular clear windows in an opaque film for defining the transmitted beam and optical reference position.
A chrome-on-glass pinhole is a small circular transparent region in an opaque film. It defines a compact light source or spatial selection point while the glass supports the pattern. Arrays repeat this geometry at specified locations.
Choose a single pinhole for a local optical reference or spatial filtering arrangement compatible with glass. Choose an array when several reference points, channels or repeated image locations are needed.
A clear pinhole transmits light within a blocked field; a dark dot blocks light within a clear field. A glass-supported pinhole also differs from a drilled or electroformed metal aperture because the substrate remains in the optical path.
Clear diameter, circularity, surrounding opaque area, array pitch and fiducials define the pattern. Substrate transmission and film optical density must be considered at the illumination wavelength.
A glass-supported aperture or aperture array with defined clear regions. The physical support stays continuous beneath the openings in the film.
| Optical diameter | Clear aperture and edge requirement |
|---|---|
| Aperture centre | Centred or offset from a specified datum |
| Substrate format | Mounting area, thickness and glass dimensions |
Measure aperture diameter and circularity separately from centre placement and array pitch. Check unwanted clear defects outside the designed aperture.
| Configuration | Useful for | Selection detail |
|---|---|---|
| Single clear aperture | One local optical reference | Diameter and location serve different functions |
| Clear aperture array | Multiple transmitted reference points | Define centre positions independently of diameter |
| Dark-dot array | Opaque features in a clear field | Opposite polarity; adapt illumination and detection |
Reducing the diameter reduces admitted light and changes the diffracted field. The useful diameter depends on wavelength, numerical aperture and the role of the pinhole in the system. It cannot be selected from a desired image spot size alone.
A camera-calibration algorithm configured for dark circles may not detect bright apertures without adapting the detector and lighting. Define the transmitted image and the surrounding field explicitly before choosing polarity.
An array can have uniform diameters but incorrect centre positions, or correct centres with variable diameters. Position controls geometric relationships; diameter and edge quality influence transmitted light and feature detection.
| Control item | Information to confirm |
|---|---|
| Geometry and position |
|
| Substrate and optical path | Specify glass grade, thickness, wavelength and illumination side. Review transmission and reflections in the actual optical arrangement. |
| Inspection and acceptance | Measure aperture diameter and circularity separately from centre placement and array pitch. Check unwanted clear defects outside the designed aperture. |
| Drawing and revision | Provide a 1:1 DWG with declared units, clear and opaque layers, viewing direction, active area and the approved revision. |
Defined circular clear apertures in an opaque coating.
No. The opening is in the film; light continues through the glass substrate.
Yes, if the illumination, coordinate geometry and feature detector are compatible. Bright apertures and dark dots may need different detection settings.
No. Wavelength, power density and exposure conditions affect suitability. Aperture geometry by itself establishes neither damage threshold nor laser-power handling.
Circular chrome-on-glass apertures define an optical opening with a specified diameter and position.
Dimension the clear aperture and its location relative to the substrate or optical axis. Define film side and opaque surrounding area.
Diameter, centre position, substrate outline, thickness, film side and opacity.
A single aperture limits one optical region. An array provides openings at multiple known positions; choose for the required channels or reference points.