Achieving photorealistic engravings on wood and acrylic with a CO2 laser requires a blend of proper image preparation, machine calibration, and material-specific settings. Below is a comprehensive guide to help you produce stunning results.

1. Image Preparation: The Critical First Step

Key Principle: Your laser doesn’t print in shades of gray—it creates dots (halftones) of varying sizes/spacing to simulate tones. Proper image editing is 70% of the success.

For Both Wood & Acrylic:

• Convert to Grayscale: Start with a high-contrast, high-resolution photo (300 DPI minimum).
• Adjust Contrast & Levels: Use software (Photoshop, GIMP, LightBurn’s image tools) to maximize mid-tone detail. Boost contrast slightly to define shadows and highlights.
• Apply a Halftone Filter/Dithering: This is non-negotiable.
  • Method: In your design software (like LightBurn), use the "Jarvis", "Floyd-Steinberg", or "Stucki" dithering pattern. These create a natural, dot-based pattern ideal for laser engraving.
  • Avoid: Standard "Halftone" circles in Photoshop. Laser-specific dithering is superior.
• Invert for Acrylic: For subsurface engraving (the classic frosted look), invert your image. Black in your design will become the most engraved (frosted) area.

2. Machine & Software Setup

• Focus: Ensure your laser is perfectly focused on the material surface. Use your machine’s focus tool or gauge.
• Lens: A 2.0" lens is ideal for detail work over a standard 2.5" or 4".
• Software: LightBurn is highly recommended for its exceptional image handling and dithering controls.
• Test Grid: Always run a power/speed test grid on a scrap piece of your exact material first. This is the single most important step for dialing in settings.

3. Material-Specific CO2 Laser Settings

DISCLAIMER: These are starting points. Always test on scrap material first, as results vary by machine, air assist, and material brand.

A. For Wood (Natural, Light-Colored Woods like Maple, Birch, Cherry, Basswood)

The goal is to vaporize material at different depths to create shades.

• Engraving Type: Raster (back-and-forth lines).
• Power (50W Laser Example):
  • Range: 15% - 25% of max power.
  • Reason: Too high power will char and lose detail. Lower power allows for subtle tonal variation.
• Speed:
  • Range: 300 - 600 mm/s (faster for lighter engravings, slower for darker/deeper).
  • Sweet Spot: Start at 400 mm/s.
• DPI/LPI (Lines Per Inch):
  • Range: 300 - 600 DPI.
  • Recommendation: 500 DPI for an excellent balance of detail and engraving time.
• Process: Run one pass only. Multiple passes will blur detail.
• Pro-Tips for Wood:
  • Air Assist: Use LOW air assist or even turn it off to reduce cooling and allow for a slightly darker, crisper burn. (Test this!).
  • Masking: Apply transfer tape to the wood surface before engraving to prevent smoke residue (halo effect). Peel off after.
  • Finish: Lightly sand with fine grit (400+) after engraving to clean soot, then apply a clear lacquer or wax to make the image pop.

B. For Acrylic (For Subsurface/Frosted "Photo" Engraving)

The goal is to create fine, frosted micro-cracks inside the acrylic, not on the surface. You need cast acrylic, not extruded. Extruded acrylic melts poorly and will not produce a clear frosted image.

• Engraving Type: Raster.
• Power (50W Laser Example):
  • Range: 8% - 15% of max power.
  • Reason: Very low power is needed. High power will melt and bubble the surface, destroying clarity.
• Speed:
  • Range: 150 - 350 mm/s.
  • Sweet Spot: Start at 250 mm/s.
• DPI/LPI:
  • Range: 500 - 1000 DPI.
  • Recommendation: 600 DPI for a smooth, photographic look.
• Process: One pass only is critical.
• Pro-Tips for Acrylic:
  • Air Assist: Use HIGH air assist to keep the surface clean and cool.
  • Focus: For a deeper, more pronounced frost, some users defocus by +0.5mm to +1.0mm. Test this carefully.
  • Backing: Place a piece of white paper or cardstock behind clear acrylic when displaying. For a colored effect, use colored backing.
  • Cleaning: Wash gently with soap and water. Do not use solvents or abrasive cloths.

4. Quick-Reference Settings Chart

(For an 80W laser, reduce these percentage values proportionally—e.g., 10% on a 50W ≈ 6-7% on an 80W for similar energy density.)

5. Troubleshooting Common Issues

• Image is Too Dark/Blurry (Wood): You are using too much power or moving too slow. Increase speed and/or reduce power.
• Image is Too Faint (Wood): Not enough power or too fast. Reduce speed slightly.
• Acrylic is Melting/Bubbling: Power is far too high. Reduce power dramatically (start at 6-8% on a 50W). Ensure it's cast acrylic.
• Lack of Detail (Both): DPI is too low or you used the wrong dithering pattern. Use 500+ DPI and Jarvis/Floyd-Steinberg dithering.
• Halo/Smoke Stains (Wood): Use masking tape and ensure good exhaust ventilation.

Final Golden Rule: TEST, TEST, TEST.

Create a small test file with a range of grays and fine details. Run it with varying powers and speeds on your specific material. Document your results. This 10-minute investment will save you hours of frustration and wasted material, leading you to the perfect "sweet spot" for your machine.

By mastering image prep and patiently dialing in these variables, you can consistently produce gallery-quality photographic engravings on both wood and acrylic. Happy lasering