Repeated transparent circular openings for multi-point illumination, image registration and optical channel checks.
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.
| Aperture diameter | Clear-circle diameter at the patterned film |
|---|---|
| Array geometry | Pitch, rows, columns and coordinate origin |
| Imaging conditions | Wavelength, magnification and sampling |
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. |
Bright-point arrays for compatible imaging and alignment tests.
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.
Pinhole array targets place transmitting circular apertures at known coordinates in an opaque film on glass.
Specify diameter, pitch, row geometry and origin together; match the array to illumination and image sampling.
Diameter, centre spacing, rows and columns, origin, polarity, substrate and active area.
The transparent film openings still have glass underneath. Physical flow-through holes must be specified separately.