Compensated distance measurement methods and apparatus
First Claim
1. Apparatus for measuring distance, comprising:
- a transmitter operative to emit a transmit light signal toward a target at an emission time,a receiving system comprising;
an optical subsystem to receive a return light signal, andan opto-electrical converter to convert the return light signal to a return electrical signal,at least one attenuator to apply an attenuation to at least one of the return light signal and the return electrical signal, the attenuation varying, as time passes, after emission of the transmit light signal, according to a time-dependent attenuation function such that the attenuation is maximum at a critical time elapsed since the emission time of said transmit light signal, said critical time being dependent on at least one geometrical parameter of the optical subsystem,a detection unit to determine a receive time from the return electrical signal, anda processor unit to calculate a measured distance based on at least the emission time and the receive time.
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Accused Products
Abstract
A transmit light signal is emitted toward a target at an emission time. An optical subsystem of a receiving system receives a return light signal which is converted to a return electrical signal. At least one attenuator applies an attenuation to at least one of the return light signal and the return electrical signal. The attenuation varies, as time passes, after emission of the transmit light signal, according to a time-dependent attenuation function such that the attenuation is maximum at a critical time elapsed since an emission time of the transmit light signal. The critical time is dependent on at least one geometrical parameter of the optical subsystem. A receive time is determined from the return electrical signal. The emission time and the receive time are used to calculate a measured distance.
4 Citations
20 Claims
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1. Apparatus for measuring distance, comprising:
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a transmitter operative to emit a transmit light signal toward a target at an emission time, a receiving system comprising; an optical subsystem to receive a return light signal, and an opto-electrical converter to convert the return light signal to a return electrical signal, at least one attenuator to apply an attenuation to at least one of the return light signal and the return electrical signal, the attenuation varying, as time passes, after emission of the transmit light signal, according to a time-dependent attenuation function such that the attenuation is maximum at a critical time elapsed since the emission time of said transmit light signal, said critical time being dependent on at least one geometrical parameter of the optical subsystem, a detection unit to determine a receive time from the return electrical signal, and a processor unit to calculate a measured distance based on at least the emission time and the receive time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of operating a distance measuring system, comprising:
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a. emitting a transmit light signal toward a target at an emission time, b. receiving by an optical subsystem a return light signal c. converting the return light signal to a return electrical signal, d. regulating, as time passes, after emission of the transmit light signal, an attenuation level of an attenuator for applying an attenuation to at least one of the return light signal and the return electrical signal according to a time-dependent attenuation function such that the attenuation is maximum at a critical time elapsed since the emission time of said transmit light signal, said critical time being dependent on at least one geometrical parameter of the optical subsystem, e. determining a receive time from the return electrical signal, and f. calculating a measured distance based on at least the emission time and the receive time. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification