The Spatial Filter type Speed Detector is captured uneven patterns of road surface optically and operate the speed measurement. So, the measurement cannot be operated if there are puddles on the road surface or the optical system is covered with the mud water.
As the unit is not expected to use on rainy days or in the case that there are puddles on the road surface, so only a simple rainproof measure is operated. The further waterproofing measures are not taken.
If there is possibility of entering water to the detector from the clearance when the Spatial Filter type Speed Detector is arranged in the place to be splashed with water or in the end of a water flow of the rainwater which has come down on the vehicle, please use the unit by covering regularly with the waterproof sheet such as vinyl sheet.
In this case, the light projection section becomes very hot, so please devise a plan not to attach the waterproof sheet directly to it.
Also, please note it may be a measurement error when the light receiving signal is affected, such as the case that the waterproof sheet is spread out to the light path of the light receiving section.
The purpose of the light projector is to light up the road surface to make the uneven patterns of road easy to see, so there is no affection even if the rainwater is stored in the light projection part.
However, when you operate long term measurement, water vapor reduces the projection light and it gives bad affection to the halogen lamp.
Also, when the mud water spray from the road surface enters into the light projector, irradiating light is reduced and the S/N of the detection signal is also deteriorated.
When the water is staying inside, immediately remove the light projector hood and drop the water out and clean the protection glass.
If the same phenomenon is occurred to the detection side of the optical system, it affects the imaging relation, and detection ability is remarkably lowered. Measurement cannot be operated.

In this case, please take your time to dry it in the room. If it is too wet, removing and cleaning the objective lens are necessary. Also, we recommend you to operate the recalibration of the detector.