Patent ID: 7990542

Claim:
An apparatus for interferometry including an optical system producing a first optical signal and a second optical signal, in which the first optical signal and the second optical signal are quadrature-encoded, comprising: an optical-to-digital converter configured to convert independently intensities of a first optical signal to a first digital signal of N bits and the intensities of a second optical signal to a second digital signal of N bits, such that a combination of the first digital signal and the second digital signal forms an address signal, and wherein the first optical signal and the second optical signal and the corresponding first digital signal and the second digital signal are independent of each other; two buses operatively connected to the optical-to-digital converter to receive the first and the second digital signals respectively, wherein each bus is N bits wide, and are arranged in a parallel to form an address bus for receiving the address signal of a width of at least 2×N bits; and a memory having data values loaded in memory addresses in a range of zero to two raised to a power equal to the width of the address signal, wherein the memory is connected directly to the address bus such that the address signal directly reads the data values from the memory, wherein the data values include fault indication codes.