A method for determining a measured distance between an output of a measuring device and an object comprising the steps of: producing a first light beam having a first frequency from a first laser source and a second light beam having a second frequency from a second laser source; wherein a modulation period is identical for both the first laser source and the second laser source, the first laser source is 180° out of phase with the second laser source; chirping up the first frequency at a first rate as the second frequency is chirped down at a second rate; the first rate and the second rate being different rates; chirping up the second frequency at the second rate as the first frequency is chirped down at the first rate; combining the first light beam and the second light beam using a polarization maintaining coupler; directing the combined light beam path using an output fiber, through an angled end of the output fiber, a quarter wave plate and a partial reflector, toward the object, the partial reflector providing a reflected local oscillator path light beam associated with the combined light beam path; receiving the reflected local oscillator path light beam; receiving a target-reflected signal path light beam associated with the combined light beam path, wherein the target reflected signal path light beam, after returning to the output fiber through the quarter wave plate, is in the output fiber in a same orthogonal polarization axis of the output fiber as the reflected local oscillator path light beam in the output fiber; and wherein a polarization of backscattered light in the output fiber is orthogonal to a polarization of the reflected local oscillator path light beam in the output fiber; and heterodyning the LO path light beam and the target-reflected signal path light beam; two different beat frequencies being generated, the two different beat frequencies being proportional to the measured distance, the two beat frequencies being detected by a single detector. producing a first light beam having a first frequency from a first laser source and a second light beam having a second frequency from a second laser source; wherein a modulation period is identical for both the first laser source and the second laser source, the first laser source is 180° out of phase with the second laser source; chirping up the first frequency at a first rate as the second frequency is chirped down at a second rate; the first rate and the second rate being different rates; chirping up the second frequency at the second rate as the first frequency is chirped down at the first rate; combining the first light beam and the second light beam using a polarization maintaining coupler; directing the combined light beam path using an output fiber, through an angled end of the output fiber, a quarter wave plate and a partial reflector, toward the object, the partial reflector providing a reflected local oscillator path light beam associated with the combined light beam path; receiving the reflected local oscillator path light beam; receiving a target-reflected signal path light beam associated with the combined light beam path, wherein the target reflected signal path light beam, after returning to the output fiber through the quarter wave plate, is in the output fiber in a same orthogonal polarization axis of the output fiber as the reflected local oscillator path light beam in the output fiber; and wherein a polarization of backscattered light in the output fiber is orthogonal to a polarization of the reflected local oscillator path light beam in the output fiber; and heterodyning the LO path light beam and the target-reflected signal path light beam; two different beat frequencies being generated, the two different beat frequencies being proportional to the measured distance, the two beat frequencies being detected by a single detector.