Teardown: Keyence LJ-V7060 High-Speed Laser Profilometer Head

[zelo]

Hi everyone,

I recently had a dead Keyence LJ-V7060 head (unit was not recognized by the controller). Since these units are usually "black boxes" in the industry, I decided to perform a destructive teardown to see the engineering behind a 64kHz profilometer.

I use several of these systems in my own builds, so I was particularly interested in the optical path and how they handle thermal drift.

Exterior and Housing The LJ-V7060 is built like a tank. Heavy-duty cast aluminum housing, held together by high-torque Torx screws. You can see the 405nm (Blue/Violet) optics and the typical industrial ruggedness.
 

Internal Layout After opening it up, the internal structure reveals a main logic board in the top section and a separate opto-mechanical base plate. The isolation between the processing electronics and the optical path is quite clear.
 

The Laser Module & Thermal Management The laser module is fixed with a white, flexible RTV-like material. It seems Keyence chose this for vibration damping and to allow for thermal expansion without losing line alignment. The empty shell shows machined surfaces and thermal pads designed to dump heat from the FPGA/DSP directly into the housing.
 

CMOS Sensor side In contrast to the laser module, the CMOS sensor module is potted with a hard, resin-like material (likely epoxy) to ensure absolute rigidity for the triangulation geometry.
 

If you’re curious about the hardware, the integration, or just general nature of this hardware, feel free to ask. I’ll do my best to answer.

Enjoy the hardware porn!

[zelo]

I’ve managed to get into the laser module itself. I’d love to hear from someone more experienced in high-end optics to confirm this, but  here is what I’ve observed so far:
- The Beam Combiner: There is a glass cube in the middle where the light paths meet. Since there are two laser sources (one from the top, one from the right?), it looks like this is a Polarizing Beam Splitter used to join them into a single line.
- The Unknown Diode: There is a small diode on the left side, but it doesn't look like a laser to me.
- Mounting: Interestingly, the laser module isn't hard-bolted to the frame; it's held by a flexible white RTV-like compound.

If anyone knows the exact optical black magic going on here, please weigh in!

Front:


Left:


Right:


Back:


Bottom:

[zelo]

PCB

[mjs]

Can you post pictures of the laser boards and laser diodes ? Was the beam splitter removed and turned between the pictures ?

When splitter prism is behind the clips, it looks like the photodiode (smaller board) could receive light from both side and top lasers for monitoring / optical power control.

I don't know why they would use two lasers, maybe to reduce polarization effects or even have different focus distances ?

The line quality these things project is superb, so this is interesting to see!

[zelo]

I think I will be able to make those photos in the next few days. I'll try to get some high-res macro shots of the diodes and the monitor board.

Regarding the prism – it's very possible I switched its position during teardown. It was held by these clips and a little bit of glue, but once they were off, it was free to move.

However, I found a very interesting page in the Keyence docs (attached below) that explains the dual-laser setup. It's their "Double polarisation function". The system shines X- and Y-polarised light at the target and analyzes the reflections on the CMOS separately to identify and cancel out stray light/multiple reflections. This is especially useful for complex metal targets.

Your theory about the smaller board being a photodiode for monitoring both lasers seems very likely, especially to keep the power of both polarization components balanced.

I’ll keep you guys posted!