Range-compensating lens for non-imaging active optical systems

In many active optical systems where the light is supplied, such as a range finder or optical radar, there is a possibility that the detector (pixel) can be destroyed if significant signal is returned or at the very least blinded for a period of time. This is because the designer struggles with the "one over range squared" loss, which can amount to significant attenuation in the return signal, given the range requirements. When pushing the range limit requirement, the sensor is in need of a large dynamic range detector and/or some form of detector protection when the target is quite close. There is then a search for a range-compensating lens. This work proposes a lens that attempts to compensate for range signal loss passively and instantaneously by combining lens elements in parallel rather than in series, as is typically done. The proposed lens is relatively simple, compensates for range, albeit not perfectly, and has its own drawbacks.