Method and arrangement for measuring distances optically with high precision

Claim 3

A method according to claim 1, whereby a measurement signal is produced by a counting oscillator and is modulated upon the optical carrier and after being received is converted immediately in one channel and in a second channel after passing through the measuring path twice to a lower frequency, the outputs of the one and second channels supplied to said counting device for evaluation, and whereby the frequency conversion is selected to maintain a desirable relationship between the measurement of the transit time and the phase measurement.

Claim 4

A method according to claim 1 comprising an optical transmitter modulated by the measuring signal and an opto-electronic receiver with a counting deviCe in which the modulation means of the optical transmitter is designed for modulating with a periodic modulation and for individual impulse control, the opto-electrical receiver having a first channel receiving the measurement signal before transmission and a second channel receiving the measuring signal after it has twice passed through the measuring path, said first channel with its output connected to the first control input of the counting device, and the second channel with its output connected to a second control input of the counting device.

Claim 5

A method according to claim 3, whereby the measuring signal received from the output of the optical transmitter is fed directly to the first channel of the opto-electronic receiver.

Claim 6

A method according to claim 4, whereby at least the second channel includes an opto-electrical converter, a frequency converter connected to said opto-electrical converter, a pulse former connected to said opto-electrical converter and designed for the producing of a control impulse from the zero passage of the measurement signal converted downwardly in frequency.

Claim 7

A method according to claim 5, whereby an electronic switch is mounted in the path of the first channel of the opto-electronic receiver behind the impulse-forming network.

Claim 8

A method according to claim 6, whereby both channels have their outputs connected to control terminals of the counting device for measuring the transit time, and a pair of shorting switches in parallel with portions of said channels.

Claim 9

A method according to claim 7, whereby the counting oscillator with a frequency f1 is connected to the counting device, a start-stop switch connected between the counting device and the counting oscillator, and whereby for downward conversion of the signal received by the opto-electronic receiver in both channels a conversion generator has a frequency f2 which satisfies the equation f2 < or = f1 (1 - phi ) whereby phi represents the relation of the measurement precision to be required for measuring the transit time to the measurement precision required for phase measurement.

Claim 10

A method according to claim 8 whereby for ''''start'''' and ''''stop'''' of the counting device the start-stop switch is controlled by outputs of the one and second channel.

Claim 11

The method according to claim 9 whereby the optical transmitter is a luminescence device.

Claim 12

The method according to claim 9 whereby the optical transmitter is a Laser.

Claim 13

The method according to claim 9 whereby the optical transmitter consists of the combination of a Laser for measuring the transit time and a luminescence device for the phase measurement.

Claim 14

The method according to claim 9 whereby the optical transmitter is a gas Laser.

Claim 15

The method according to claim 13 whereby the optical transmitter comprises a gas Laser and is equipped with means for impulse modulation by using the principle of phase coupling of its emission, and an additional modulation installation operative as a gate circuit connected to said Laser for separating individual impulses from the impulse sequence for making the measurement of the transit time.

Claim 16

The method according to claim 14, whereby the installation for impulse modulation comprises an electro-optical crystal, one of the two resonator mirrors of the Laser is fastened to the electro-optical crystal, a generator is connected to the crystal to stimulate it into mechanical oscillations to periodically change the resonator length of the Laser, and whereby the period of the oscillation of this generator is selected equal to the single or double transit time of the emission within the resonator.

Claim 17

Distance measuring means comprising: means for transmitting and receiving optical energy from a reflector; means for modulating said optical energy; a pair of channels in said transmitting and receiving means; a first one of said channels receiving a portion of the transmitted energy; the second channel receiving optical energy from said reflector, a counting generator modulating said means for transmitting; a start-stop gate receiving an output from said counting generator and connected to the outputs of said pair of channels; a distance meter connected to said start-stop gate; switch means for disconnecting said counting generator from said transmitting means; pulsing means connected to said transmitting means to transmit a pulse when said counting generator is disconnected from said transmitting means, and said start-stop gate receiving said pulse when transmitted and also receiving the pulse after reflection from said reflector.

Claim 18

Distance measuring means comprising: means for transmitting and receiving optical energy from a reflector; means for modulating said optical energy; a pair of channels in said transmitting and receiving means; a first one of said channels receiving a portion of the transmitted energy; the second channel receiving optical energy from said reflector, a counting generator modulating said means for transmitting; a start-stop gate receiving an output from said counting generator and connected to the outputs of said pair of channels; a distance meter connected to said start-stop gate; switch means for disconnecting said counting generator from said transmitting means; pulsing means connected to said transmitting means to transmit a pulse when said counting generator is disconnected from said transmitting means, and said start-stop gate receiving said pulse when transmitted and also receiving the pulse after reflection from said reflector.

Claim 19

Apparatus according to claim 16 wherein each of said channels comprise opto-electronic converters, and pulse formers, a pulse switch connected in the first channel, and a pair of shorting switches connected in parallel with portions of the first and second channels.