Bonding Lenses, Prisms & Optics with UV
Optical bonds have to hold alignment to a fraction of a degree and cure without inducing stress that would distort the wavefront. UV-cure optical adhesives let you align the optic exactly, then lock it in seconds, no drift during a long cure, no thermal soak that warps the mount.
You align the optic while the adhesive is still liquid, then fire the UV to freeze that alignment. Because the cure is on-demand and near-instant, the optic can’t drift the way it can during a slow ambient or oven cure. Matching the wavelength to what the glass transmits ensures the bond line actually cures.
A broad-spectrum arc cures whatever optical adhesive you qualify and its longer wavelengths pass through most optical glass to reach the bond line. For 405 nm-cure optical adhesives on a fixtured bench, a matched SkyBeam channel works well too.
Step by Step
- 1 Choose a low-stress optical adhesive. Pick an adhesive formulated for optics, low shrinkage and low cure stress, with a wavelength your glass transmits.
- 2 Align while liquid. Set the optic to alignment with the adhesive still wet. This is the moment the cure will freeze, so get it right first.
- 3 Cure through the optic. Fire the UV to lock alignment. Use a heat filter so IR from an arc source doesn’t heat and distort the optic during exposure.
- 4 Verify alignment and full cure. Confirm the optic held alignment and the bond line is fully cured, a radiometer verifies real dose reached the joint through the glass.
Common Pitfalls
- Skipping the heat filter on an arc source, IR can heat and distort a precision optic during cure.
- A wavelength the glass blocks, the bond line never sees the light; match wavelength to the optic’s transmission.
- High-shrinkage adhesive, cure shrinkage pulls alignment; use a low-stress optical formula.
Questions
How do you bond an optic without moving it during cure?
Align the optic while the UV adhesive is still liquid, then fire a spot cure that sets the bond in seconds, far too fast for the optic to drift, unlike a slow ambient or oven cure.
Does UV heat damage the optic during curing?
A UV LED source runs cool. With a broad-spectrum arc, add a heat filter (UV2554, 300–450 nm) so infrared from the lamp doesn’t warm and distort a precision optic while it cures.
How do I make sure the bond line cures through the glass?
Use a wavelength the glass transmits and an adhesive tuned to it, then verify with a radiometer that real dose reaches the joint through the optic. Longer UVA wavelengths pass through most optical glass.
