Uploaded March 2021 | Updated September 2026, 2 hours ago
If you want to measure/compare RAW laser power without an expensive LPM you can use a peltier cell. A peltier cell cost less than 5$. I use a TEC1-12704 30x30mm Peltier Cell
Ratio between voltage and LPM wattage is near 1/10 (100mV = 1W)
NOTE: I have black-painted one side of the pelter cell so the laser light is better absorbed. This is very important as because the white color of the peltier cell reflect the laser light.
Peltier cell: https://s.click.aliexpress.com/e/_AAtxLG
Multimeter: https://s.click.aliexpress.com/e/_AsG2Qq
It's a bit crude way but it works!
However the RAW power it is not the only one things that matter, but the lens that is used in the module is also very important for two reasons:
- the lens causes a power drop, as it is never 100% transparent. The more complex it is (made up of more elements) the more power is filtered by the lens. If you have a detachable lens you can check this behavior by measure the power with and without the lens.
- the lens is responsible for the shape and size of the focus point. If the focal point isn't small, you don't get good power density. Usually more complex lens is needed to obtain better focus.
So a good balance between transparency and optical performance is necessary to have a quality lens, to be able to cut well.
For this reason, in addition to a raw power test, I always suggest making "on material" comparisons between different lasers. The problem is finding the same material in different places in order to compare results with other people!
If you want to measure/compare RAW laser power without an expensive LPM you can use a peltier cell. A peltier cell cost less than 5$. I use a TEC1-12704 30x30mm Peltier Cell
Ratio between voltage and LPM wattage is near 1/10 (100mV = 1W)
NOTE: I have black-painted one side of the pelter cell so the laser light is better absorbed. This is very important as because the white color of the peltier cell reflect the laser light.
Peltier cell: https://s.click.aliexpress.com/e/_AAtxLG
Multimeter: https://s.click.aliexpress.com/e/_AsG2Qq
It's a bit crude way but it works!
However the RAW power it is not the only one things that matter, but the lens that is used in the module is also very important for two reasons:
- the lens causes a power drop, as it is never 100% transparent. The more complex it is (made up of more elements) the more power is filtered by the lens. If you have a detachable lens you can check this behavior by measure the power with and without the lens.
- the lens is responsible for the shape and size of the focus point. If the focal point isn't small, you don't get good power density. Usually more complex lens is needed to obtain better focus.
So a good balance between transparency and optical performance is necessary to have a quality lens, to be able to cut well.
For this reason, in addition to a raw power test, I always suggest making "on material" comparisons between different lasers. The problem is finding the same material in different places in order to compare results with other people!
