A sensing device for measuring an offset along a longitudinal axis (L) comprising: a housing including a front surface having a plurality of slots (242, 244, 246; 412, 414, 416); two or more arrays of optical sensors (202, 204, 206; 302, 304, 306; 402, 404, 406) linearly aligned along the longitudinal axis (L), at least one of the two or more arrays being offset along the longitudinal axis (L) with respect to others of the at least two arrays while overlapping in longitudinal position along said longitudinal axis (L) relative to the others of the at least two arrays such that the at least one of the two or more arrays has different end points as measured along the longitudinal axis (L) of the device (200; 300; 400, 500) than the others of the at least two arrays; a microcontroller coupled to the two or more arrays of optical sensors (202, 204, 206; 302, 304, 306; 402, 404, 406) and configured to determine a positional offset along the longitudinal axis (L) at which a laser reference beam is detected by at least one of the two or more optical sensor arrays (202, 204, 206; 302, 304, 306; 402, 404, 406); wherein each of the optical sensors of the two or more arrays (202, 204, 206; 302, 304, 306; 402, 404, 406) are positioned within the housing directly underneath one of the plurality of slots (242, 244, 246; 412, 414, 416), and are commensurate in size with the slots underneath which they are positioned, so as to reduce an angle of incidence of radiation received by the optical sensors, ensuring that the substantial majority of radiation detected is incident normal to the surface of the sensing device; wherein the two or more arrays of optical sensors (202, 204, 206; 302, 304, 306; 402, 404, 406) together cover all positions within the span of distance along the longitudinal axis (L). a housing including a front surface having a plurality of slots (242, 244, 246; 412, 414, 416); two or more arrays of optical sensors (202, 204, 206; 302, 304, 306; 402, 404, 406) linearly aligned along the longitudinal axis (L), at least one of the two or more arrays being offset along the longitudinal axis (L) with respect to others of the at least two arrays while overlapping in longitudinal position along said longitudinal axis (L) relative to the others of the at least two arrays such that the at least one of the two or more arrays has different end points as measured along the longitudinal axis (L) of the device (200; 300; 400, 500) than the others of the at least two arrays; a microcontroller coupled to the two or more arrays of optical sensors (202, 204, 206; 302, 304, 306; 402, 404, 406) and configured to determine a positional offset along the longitudinal axis (L) at which a laser reference beam is detected by at least one of the two or more optical sensor arrays (202, 204, 206; 302, 304, 306; 402, 404, 406); wherein each of the optical sensors of the two or more arrays (202, 204, 206; 302, 304, 306; 402, 404, 406) are positioned within the housing directly underneath one of the plurality of slots (242, 244, 246; 412, 414, 416), and are commensurate in size with the slots underneath which they are positioned, so as to reduce an angle of incidence of radiation received by the optical sensors, ensuring that the substantial majority of radiation detected is incident normal to the surface of the sensing device; wherein the two or more arrays of optical sensors (202, 204, 206; 302, 304, 306; 402, 404, 406) together cover all positions within the span of distance along the longitudinal axis (L). <EOS>