Patent ID: 7626686

Claim:
A surveying instrument comprising: a light emitting section for emitting light a pulse; a beam splitter for branching the light pulse emitted from the light emitting section into a reference light and a measurement light; a reference light path for letting the reference light travel through; a part of a measurement light path for letting the measurement light travel through for irradiation on an object to be measured and letting the measurement light reflected from the object to be measured travel through, the part of the measurement light path having a multiplex pulse generating section for generating, from the measurement light, multiplex light pulses at different times with different intensities; a light receiving section for receiving the reference light from the reference light path and receiving the multiplex light pulses from the measurement light path; a light coupler for coupling together the light from the reference light path and the light from the measurement light path to guide the light from the reference light path and the light from the measurement light path to the light receiving section; a pulse selecting section for selecting, from the multiplex light pulses received with the light receiving section, a light pulse for use in measurement; and a measurement amount calculating section for calculating, according to the difference in light receiving time between the light pulse selected with the pulse selecting section and the reference light and according to the order of receiving the selected light pulse, a difference in required time between the time required for the measurement light traveling through a normal measurement light path and the time required for the reference light traveling through the reference light path, or for calculating a distance to the object to be measured.