# US 2017/0285149 A1 · Distance measurement instrument > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0285149 A1 - Document ID: US20170285149A1 - Status: Published application - Kind: A1 - Application number: 15/623,944 - Filed: 2017-06-15 - Published: 2017-10-05 - Earliest claimed: 2014-12-22 - Assignees: Trimble Inc. - Applicants: Trimble AB - Inventors: Johan Lekås; Set Svanholm; Alex Slawomir Kosakowski - Web page: https://patentgrep.com/patent/US20170285149A1 ## CPC - G01S 7/4817: {relating to scanning} - G01S 7/4865: Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487) - G01S 7/489: Gain of receiver varied automatically during pulse-recurrence period - G01S 17/10: using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) - G01S 17/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES ## Abstract A distance measurement instrument and a method of operating a distance measurement instrument are disclosed. According to some embodiments, a transmit light signal is transmitted by a transmitter unit along a transmit path at an emission time and a return light signal is received by a receiver unit at a receive time along a receive path. The return light signal is converted to a return electrical signal. At least one of the transmit path and the receive path is deflected by a deflection module at a deflection angle relative to an optical axis of the instrument. A time-dependent attenuation function is selected based on information relative to the deflection angle and attenuation is applied by an attenuator to at least one of the return light signal and the return electrical signal according to the selected time-dependent function. A measured distance may be determined by a processor unit based on at least the emission time and the receive time. ## Claims ### Claim 1 A distance measurement instrument, comprising: a transmitter unit configured to emit a transmit light signal toward a target along a transmit path at an emission time; a receiver unit configured to receive at a receive time a return light signal along a receive path and to convert the return light signal to a return electrical signal; at least one deflection module configured to deflect at least one of the transmit path and the receive path with a deflection angle relative to an optical axis of the instrument; at least one attenuator configured to apply an attenuation to at least one of the return light signal and the return electrical signal according to a time-dependent function selected based on information relative to the deflection angle; and a processor unit configured to determine a measured distance to the target based on at least the emission time and the receive time. ### Claim 2 (depends on 1) The instrument according to claim 1, wherein the deflection module comprises at least one deflection element mounted for rotational motion and/or translational displacement such that at least one of the transmit path and the receive path is deflected with rotation and/or translational displacement of the deflection element. ### Claim 3 (depends on 2) The instrument according to claim 2, further comprising a sensor operative to detect an angle of rotation of the deflection element and/or a displacement sensor operative to detect a translational displacement of the deflection element, wherein the information relative to the deflection angle is the detected angle of rotation and/or the detected translational displacement. ### Claim 4 (depends on 2) The instrument according to claim 2, wherein the information relative to the deflection angle includes a starting position of the deflection element relative to the instrument optical axis and at least one of a rotation speed, a translation speed, and a displacement profile of the deflection element. ### Claim 5 (depends on 2) The instrument according to claim 2, further comprising a deflection lens, wherein optical displacement due to the deflection element is converted to optical deflection, to produce angular deflection of the transmit path and/or the receive path across the instrument optical axis. ### Claim 6 (depends on 2) The instrument according to claim 2, wherein the deflection element comprises at least one of a prism, a multi-faceted mirror, and a disk having a scalloped curving mirrored surface. ### Claim 7 (depends on 1) The instrument according to claim 1, wherein the time-dependent attenuation function includes a maximum of attenuation at a critical time elapsed since the emission time of said transmit light signal. ### Claim 8 (depends on 7) The instrument according to claim 7, wherein the critical time is dependent on at least one geometrical parameter of an optical subsystem with which the return light signal is received at the receiver unit. ### Claim 9 (depends on 1) The instrument according to claim 1, further comprising a front lens having an optical path along the instrument optical axis, wherein the deflection module is located optically between the front lens and at least one of the transmitter unit and the receiver unit. ### Claim 10 (depends on 1) The instrument according to claim 1, wherein the measurement instrument is further configured to regulate the attenuation of said attenuator for a travelling transmit light signal, as time passes, from a time event related to the emission of the travelling transmit light signal until reception of the return light signal corresponding to said travelling transmit light signal or until emission of a subsequent transmit light signal or until a time period elapsed since said time event exceeds a threshold. ### Claim 11 A method of operating a measurement instrument, comprising: transmitting a transmit light signal along a transmit path at an emission time; receiving at a receive time a return light signal along a receive path; deflecting at least one of the transmit path and the receive path at a deflection angle relative to an optical axis of the instrument; converting the return light signal to a return electrical signal; selecting a time-dependent attenuation function based on information relative to the deflection angle; applying an attenuation to at least one of the return light signal and the return electrical signal according to the selected time-dependent function; and determining a measured distance based on at least the emission time and the receive time. ### Claim 12 (depends on 11) The method according to claim 11, further comprising detecting an angle of rotation and/or a translational displacement of a deflection element arranged to deflect said at least one of the transmit path and the receive path, wherein the information relative to the deflection angle includes the detected angle of rotation and/or the detected translational displacement. ### Claim 13 (depends on 11) The method according to claim 11, wherein the information relative to the deflection angle includes a starting position of a deflection element arranged to deflect said at least one of the transmit path and the receive path relative to the instrument optical axis and at least one of a rotation speed, a translation speed, and a displacement profile of said deflection element. ### Claim 14 (depends on 11) The method according to claim 11, wherein the time-dependent attenuation function includes a maximum of attenuation at a critical time elapsed since the emission time of said transmit light signal. ### Claim 15 (depends on 14) The method according to claim 14, wherein the critical time is dependent on at least one geometrical parameter of an optical subsystem with which the return light signal is received. ### Claim 16 (depends on 1) The instrument according to claim 1, further comprising a center unit having the instrument optical axis as optical axis and wherein said at least one deflection module is arranged within the center unit. ### Claim 17 (depends on 16) The instrument according to claim 16, wherein the center unit is arranged to be mounted for rotation about a trunnion axis and an azimuthal axis. ### Claim 18 (depends on 1) The instrument according to claim 1, wherein the time-dependent function is based on the optical arrangement of the deflection module in the distance measurement instrument. ### Claim 19 (depends on 1) The instrument according to claim 1, wherein the time-dependent function depends on the orientation, position and/or configuration of the deflection module in the distance measurement instrument. ### Claim 20 (depends on 1) The instrument according to claim 1, wherein a number of time-dependent attenuation functions are calibrated or known for the distance measurement instrument such that, for a certain orientation or displacement of the deflection module, a certain time-dependent attenuation function is used.