with the 638 nm laser passing through the polarized element regarding the second embodiment the two lasers are multiplexed it has been noted that the signal received by the 740 nm pd of the present invention is representative of both the veins and the surface topology of the patient put another way the surface of the patient affects the reflected signal this is not desirable in that the area of interest is the veins of the patient and not the surface topology of the patient thus by using a second pd for receiving the 630 nm reflected signal the 630 nm signal the topology can be subtracted from the 740 nm signal topology veins yielding a signal that is solely the veins topology veins topology veins in this system the microprocessor 250 or state machine circuit as seen in fig8 can record the reflection from the visible laser and the ir laser can be turned on for one frame every other frame or every other scan line hence a new signal would contain a combined laser reflection the new signal would then be subtracted from the visible signal only thus leaving the if signal the advantage here is that the visible laser does not have to be turned off which has the benefit of not attenuating the visible light while reading the if laser reflection other configurations may include a multi laser array.