Greyscale Glass Photomask
GB £0.00
CUSTOM MADE GREYSCALE PHOTOMASK
FOR PRICE, PLEASE REQUEST QUOTE
Availability:
In stock
SKU
GreyPM
A greyscale image represents varying intensity levels per pixel, typically ranging from 0% (fully transparent) to 100% (fully black). Our process is binary—each pixel is either on or off—so we cannot reproduce true greyscale in the photographic or printing sense. However, we offer a solution suitable for most applications using a technique known as pixelation or dithering.
There are two primary customer requirements for greyscale masks:
1. **Optical Greyscale** — For applications where a region of the photomask must appear grey to a camera, lens, or visual system. This is achieved by using a halftone (dithered) pattern. If the individual dithered pixels are smaller than the resolving power of the optics—typically 50% smaller—they blend visually into a uniform grey. This method is highly effective for most optical requirements.
2. **Transmission Greyscale** — For applications involving exposure of photoresist through variable transmission levels, often in 3D lithography. Dithering can partially simulate this effect but success depends heavily on resist type, resist thickness, and the pixel size. Results may require significant experimentation.
DITHERED GREYSCALE OPTICAL MASKS
Dithering simulates greyscale by arranging binary dots or patterns to visually appear as varying tones. This technique, long used in printing, is enhanced by our capability to generate extremely small pixel sizes.
We convert greyscale or colour images using graphic software (e.g., CorelDRAW, Adobe Illustrator) to apply a dithering or halftone process. The result is a binary image that appears grey to a camera or lens unable to resolve individual pixels. We recommend using a pixel size at least 20% smaller than the smallest resolvable size in your optical system.
DITHERED PATTERNS
We offer several dithering methods. The most common is the "Jarvis" method, which produces a more randomized pattern with fewer internal corners, improving greyscale accuracy and minimizing rounding errors.
SIZE OF GLASS
Please specify the required final plate dimensions (length and width), including tolerances if critical. If tolerances are not important, we will offer the most cost-effective solution.
PIXEL AND PATTERN SIZE
The minimum pixel size is 2 µm, but this leads to reduced greyscale accuracy and is only viable over small areas. We recommend a minimum pixel size of 4 µm. Avoid unnecessarily small pixels, as they can result in multi-gigabyte files. Our maximum pixel grid is 20,000 × 20,000, equivalent to 400 million pixels. We recommend keeping pixel counts below 10,000 per axis to reduce cost and processing time.
Example: For a 50 mm × 50 mm pattern and a system resolution of 10 µm, we recommend using 8 µm pixels. This equates to 6,250 pixels per axis (~39 million total). In this case, enter: "50 mm pattern using 8 µm pixels."
BASE MATERIAL
Soda Lime Float Glass — various thicknesses available with multiple chrome reflectivity options.
White Diffuser Glass — 1.25 mm thick, available with black chrome only.
Quartz / Fused Silica — 2.2 mm thick, with brown or black chrome options.
CAD FORMAT
Please indicate the file format you will supply. The list on the site is not exhaustive—contact us if your format is not listed. We also offer a full drafting service based on drawings and specifications.
 |
POLARITY Masks are referred to as Clearfield (positive) or Darkfield (negative). Positive: CAD features are rendered in chrome; the background remains clear. Negative: CAD features are clear; the background is chrome. We also need to confirm the orientation of the design as viewed on your screen. Add reference text in the design and specify if it should appear right-reading or wrong-reading. |
PRODUCTION SCHEDULE
Standard turnaround is 7 days from receipt of complete artwork, order, and documentation. A checkplot is sent with every order and must be approved promptly to meet deadlines. The timeline assumes that submitted data is final and does not require revision. For large orders or high-resolution masks, please confirm lead times before requesting expedited services.
Standard (10 Days): Target lead time for most orders. Subject to workload and data completeness. Early shipment is often possible if documentation is received promptly.
Premium (4 Days): Requires complete order (data, instructions, PO) by 11:00 AM. Adds 25% to total cost.
YOUR DRAWING NUMBER
Please provide the name or number of your CAD file to match your data submission with the order.
NOTES
Use this field to specify any additional requirements or special instructions for your order.
For further details, refer to the TECHNICAL, DOWNLOAD, and FAQ sections. For assistance, please email or use the live support option.
| Specification | BASE MATERIAL
COATING
GREYSCALE |
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| FAQ | FAQ's
Q: What is dithering and how does it work? Q: What is the smallest pixel you can produce? Q: What resolution should I pick? Q: What pixel shape should I use—square or round? Q: Can I use dithering for camera calibration or contrast evaluation? Q: Can I supply my own bitmap or CAD file? Q: What materials are used? Q: How many grey levels can you simulate? Q: How large can the dithered area be? |
||||||||||||
| Downloads |
|
Material Specifications
General
BASE MATERIAL
COATING
GREYSCALE
FAQ's
Q: What is dithering and how does it work?
A: Dithering is a method of simulating greyscale by arranging black and clear pixels in a pattern. On chrome-on-glass products, this is achieved through high-resolution binary imaging followed by wet etching of the chrome layer. The resulting dot patterns simulate different grey levels when viewed or measured optically.
Q: What is the smallest pixel you can produce?
A: On chrome-on-glass substrates, we can produce pixel sizes as small as 2 µm. This allows for very high-resolution dithering patterns suitable for demanding optical and metrology applications.
Q: What resolution should I pick?
A: Select the lowest resolution that your camera or inspection system cannot resolve as pixelated. Lower resolutions keep file sizes manageable and improve tonal consistency, as the relative tolerance error is smaller. At very high resolutions, such as sub-4 µm pixels, the chrome etch characteristics must also be considered to avoid distortion of intended grey values.
Q: What pixel shape should I use—square or round?
A: Where possible, use round pixels. This is because our wet etching process tends to round off corners of square pixels, especially at small sizes. As a result, a square pixel may etch smaller than intended, leading to a darker tone than designed. Round pixels provide more reliable area coverage and tonal consistency at micro-scale. If your CAD software cannot generate circular features, you can send your file using square pixels and we will convert them. However, you must adjust the pixel density to compensate: a circle inscribed within a square has approximately 78.5% of the area. For example, to achieve a 50% tone using 8 µm square pixels, you would need to increase the number of circular pixels to approximately 63.7% fill density to maintain the intended grey level. We can assist in applying this compensation if required.
Q: Can I use dithering for camera calibration or contrast evaluation?
A: Yes. Chrome-on-glass dithered masks are ideal for high-precision contrast, resolution, and grey response testing in optical systems. Their dimensional stability and optical density make them especially suited for calibration environments.
Q: Can I supply my own bitmap or CAD file?
A: Yes. We accept binary bitmap or vector CAD formats. Please ensure resolution and feature sizes are clearly defined, and note any pixel compensation applied. If you're using square pixels, we can perform the shape conversion to round elements during processing.
Q: What materials are used?
A: Chrome-on-glass dithered products are fabricated on optically flat soda lime, borofloat, quartz, or B270 glass, with an opaque chrome layer typically 100–150 nm thick. The chrome is patterned using high-resolution laser plotting followed by photolithography and etching.
Q: How many grey levels can you simulate?
A: We recommend up to 16 levels for predictable results using binary dithering. More levels may be possible depending on resolution, area, and compensation strategy, but require testing and validation for accuracy.
Q: How large can the dithered area be?
A: The main limitation is data size. For example, a 100 mm × 100 mm area with 2 µm pixel pitch contains 50,000 × 50,000 pixels—totalling 2.5 billion pixels. At 1-bit depth, this is approximately 312.5 MB uncompressed, but actual file sizes can grow depending on format and metadata. The upper processing limit is typically around 2 GB per file. If you require extremely large areas at high resolution, we may need to split the design or recommend an alternative approach. Please contact us for guidance based on your specific requirements.
