The PO40 is Chotest's compact infrared touch probe for on-machine workpiece measurement and inspection on 3-axis and 5-axis CNC machining centers and turning-milling composites. The Φ40 mm × 50 mm body weighs just 260 g without holder, making it suitable for standard BT/HSK toolholders and automatic tool-changer magazines. A 360° infrared transmission system with anti-interference modulation links the probe to a dedicated receiver at distances up to 5 m, with Z-axis coverage across ±85°.

How does the PO40 achieve <1 μm repeatability?

The PO40 uses a 3-point kinematic trigger mechanism — the most stable configuration for touch-trigger probes. Three precision-ground contact points form a kinematic seat that constrains the stylus in six degrees of freedom until a triggering event occurs. When the stylus contacts the workpiece surface in any of the five sensing directions (±X, ±Y, +Z), the kinematic circuit opens and a trigger signal is transmitted. This design yields unidirectional repeatability below 1 μm (2δ) when tested with a 50 mm straight stylus at 480 mm/min. Trigger force is 0.5–0.9 N in XY and 5.8 N in Z, with generous overtravel limits of 12.5 mm (XY) and 6 mm (+Z) to protect the mechanism during approach.

What makes infrared transmission suitable for machining center use?

Infrared transmission offers a balance of speed, reliability, and cost that suits the majority of machining center applications. The PO40's 360° IR optical window covers ±85° in Z, ensuring the receiver maintains line-of-sight regardless of spindle orientation. The modulated IR signal resists interference from ambient lighting and coolant mist. Power comes from two 1/2 AA 3.6V lithium cells delivering approximately 150 hours of continuous trigger use — extending to 90 days or more at typical 5% duty cycles. Activation is via standard M-code, and an intelligent LED indicator displays power-on, trigger, and battery status at a glance. The IP68-sealed probe body withstands direct coolant exposure and submersion during machining.

How does the PO40 compare to other Chotest probes?

Model	PO40	PO40L	PO60
Diameter	Φ40 mm	Φ40 mm	Φ60 mm
Length	50 mm	52 mm	65 mm
Weight	260 g	280 g	850 g
Repeatability	<1 μm	<1 μm	<1 μm
Target Machine	3/5-axis MC	CNC lathe	Large gantry MC