Flir Systems 20mm CO2 lens adapter

Custom Modular Lens Holder for FLIR IR Cameras

Overview

This project is a high-precision, complete replacement for the original FLIR focusing module. Designed to bridge the gap between consumer thermal imaging and professional macro-thermography, this holder allows for the integration of CO2 ZnSe (Zinc Selenide) focus lenses directly into the camera's optical path.

By positioning the ZnSe lens as close as possible to the internal camera optics, this design maximizes image clarity, reduces distortion, and provides superior printing quality for the holder itself.

With 101.6 CO2 lens, Flir's focal distance became from 50 up to 200mm.

Design Features

• 3-Piece Modular Assembly: The body is split into three distinct sections optimized for 3D printing. This ensures clean threads, minimal support geometries, and structural integrity.

• Optimized for 20mm Optics: The current middle-insert is tailored for standard 20mm diameter ZnSe lenses, though the modular design allows for easy redesigns to accommodate alternative lens sizes.

• Serviceable Design: The threaded or interlocking nature of the assembly allows for quick lens cleaning or replacement without discarding the entire unit.

• Enhanced Optical Path: Minimizes the distance between the primary and secondary lenses to ensure the highest possible thermal resolution and minimal "tunnel effect."

Technical Specifications & Installation

• Lens Compatibility: 20mm CO2 ZnSe Focus Lens.

• Material Recommendation: High-temp resistant filament (e.g., ABS) to withstand thermal camera operating temperatures.

• Orientation Note: If using a meniscus lens, the "bulge" (convex side) must face outward (toward the subject) to ensure proper light convergence and image sharpness.

Benefits over Clip-on Adapters

Unlike standard external adapters, this replacement module offers a more secure fit, better alignment with the sensor's center axis, and a significantly more compact form factor for field use.

Printing Guide

1. Dimensional Scaling (The 1% Rule)

ABS shrinks as it cools. For a 20mm lens seat and threaded body:

• Scale the parts: Increase the X and Y scale to 101% or 101.5% in your slicer.

• Z-Scale: Keep Z at 100%. ABS shrinkage is significantly less in the Z-axis than the X/Y plane.

2. Delta Accuracy & "Magic Numbers"

The FLSUN QQ-S Pro uses 1.8° steppers with a 0.04mm full-step resolution.

• Layer Height: 0.08mm is a "magic number" (exactly 2 full steps), which is perfect for Z-consistency.

• First Layer: Set your first layer height to 0.2mm even if the rest is 0.08mm. This ensures a massive "grip" on the bed at 105°C and prevents the part from popping off mid-print.

3. Thermal Geometry Control

At 260°C with no fan, heat can "pool" in small parts.

• Minimum Layer Time: Set to 15 seconds. This prevents the 0.08mm layers from sagging or "mushing" because the nozzle stays in one spot too long.

• Outer Wall Speed: Drop to 25–30 mm/s. High speed on a Delta can introduce slight "ringing" that will make your threads feel gritty.

4. Thread & Fit Tuning

• Horizontal Expansion: If your threads or lens seat are still too tight after scaling, use a -0.05mm Horizontal Expansion (in Cura) or "XY Size Compensation" (in PrusaSlicer).

• Seam Placement: Set "Z Seam Alignment" to Random for the threads. If you have a vertical "stutter" seam, the threads might bind.

5. Post-Print Care

• Cooldown: Do not remove the parts until the bed is below 35°C. Removing ABS while warm can cause the base of your lens holder to warp slightly, ruining the alignment.