The confocal point sensor uses a point light source and detector pinhole to discriminate depth.
The laser beam emitted from the point light source is focused on a specimen through an objective lens that moves rapidly up and down. The maximum light intensity occurs when the specimen lies within the focal plane of the objective. As the objective moves closer to or farther from the specimen, however, the reflected light reaching the pinhole is defocused and does not pass through it. As a result, the quantity of light received by a detector behind the pinhole decreases rapidly. A detection signal is only generated when the maximum of light goes through the pinhole.
A precise height measurement of the illuminated point is achieved by continuously scanning along the z-axis.
Measurement principle of the
autofocus control circuit
he confocal measurement principle ensures high reliability even on steep edges and robustness against optical artifacts. This enables the LT8010 sensor to measure complex surface structures as well as structures with high aspect ratio as they occur in MEMS.
The SolarScanLT8010 can be used for various measuring tasks from fast and precise measurement of large surfaces to only single profiles. The AutoScanallows for automation of those measuring tasks.
|Spot size [µm]||2||Integrated off-axis camera|
|Vertical resolution [µm]||0,1||Magnification||200x|
|Measurement frequency [Hz]||1400|
|Stand off [mm]||5||Laser||Class II|
|Linearity [%]||±0.5||Wavelength [nm]||670|