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Aftermarket collimating and focusing lens assemblies for the Raytools BS12K cutting head. Choose the one you need from the list: the collimating assembly, Raytools 120BS5800A (D37 mm, F100 mm, 12 kW), or the focusing assembly, Raytools 120BS5900A (D37 mm, F220 mm, 12 to 15 kW). Each is the lens holder with its lens fitted.
The collimator sits directly under the fiber connector and turns the diverging beam from the fiber into a parallel beam. The focusing lens below it brings that beam to the focal spot under the nozzle. The long F220 focal length gives the larger spot and longer depth of focus the BS12K and BS15K use for thick plate.
A burned collimator costs power on every job. A damaged focusing lens shows as slow piercing, a wide or tapered kerf and dross that will not tune out. Replace the assembly that is damaged; the two are sold separately so you only buy what you need. The focusing assembly also fits the BS15K.
| Collimating Assembly | Raytools 120BS5800A: D37 mm, F100 mm, 12 kW, fits BS12K |
| Focusing Assembly | Raytools 120BS5900A: D37 mm, F220 mm, 12 to 15 kW, fits BS12K, BS15K |
| Lens Diameter | 37 mm |
| Contents | Lens holder with the lens fitted, one assembly per order line |
| Optics | Fused silica, AR coated for 1064 nm |
| Part Number | Dimensions | Raytools Part No.(SPM Part No.) | Fits |
|---|---|---|---|
| Collimating D37 F100 (120BS5800A) | D37 mm, F100 mm | 120BS5800A(SPM-LAS-2166-5800A) | BS12K |
| Focusing D37 F220 (120BS5900A) | D37 mm, F220 mm | 120BS5900A(SPM-LAS-2166-5900A) | BS12K, BS15K |
Burned or contaminated collimator
Contamination from a fiber change or a failed upper window reaches the collimating lens first. A burned collimator costs power on every cut. Replace the assembly and check the upper window.
Power loss with a clean lower window
If the lower protective window and focusing lens are clean and the machine still needs more power for the same plate, inspect the collimator.
Burned or pitted focusing lens
Slow piercing, a wide kerf and dross that will not tune out usually point to the focusing lens. Replace the assembly and fit a new protective window at the same time.
Focal shift during long cuts
A contaminated lens absorbs power and heats up, so the focus moves as the job runs. A new assembly cures it where cleaning will not.
Found this part cheaper elsewhere? Send us the listing and we will beat it under our Price Beat Guarantee. Every order is also covered by our 30 day money back guarantee.
The collimating assembly (120BS5800A, F100) is the upper lens under the fiber connector. The focusing assembly (120BS5900A, F220) is the lower lens above the protective window. Check the kit number on the holder you are replacing.
No. It is an aftermarket lens assembly made to the same diameter, focal length and mounting as the Raytools kit. The Raytools number is shown so you can match the assembly you are replacing.
Check the kit number on your current holder or in the head's parts list, and confirm the lens diameter and focal length. Collimating and focusing assemblies are not interchangeable.
Fit it in a clean area with clean gloves, handling the holder only. Fingerprints on a lens burn into the coating under laser power.
Yes. Shipping options and costs for your country are shown at checkout.
Orders typically require 1–3 business days for processing. During this time, we confirm product availability and prepare the shipment for consolidation.
We offer two shipping tiers designed to meet your operational needs. The exact costs for all shipping options will be displayed at checkout.
Express Shipping (UPS, DHL, etc.)
Ideal for urgent needs. Estimated delivery time is typically 3–5 business days after processing.
Economy Shipping
Our standard, cost-effective option. Estimated delivery time is typically 5–10 business days after processing.
Shipping costs are calculated at checkout based on your location and selected shipping method.
Once your order ships, you'll receive a tracking number via email so you can monitor your delivery.
For detailed delivery information and FAQs, please visit our Delivery Information page or contact us.

