LAB2

process：

Experimental procedures

     preparation：

1. Turn on the measurement instrument, oscilloscope and frequency meter. These devices need to be warmed for about half an hour before measurements.

 

1. Adjust the knob on the reflection prism of the measurement instrument, so that all the reflected red light enters the detector. You may use a piece of paper to observe the light spot.

 

1. Move the reflection prism cart on the rail. If the reflected red light deviates from the detector, adjust the knob again. Repeat until the reflected light spot doesn’t move when you move the prism cart. Now the reflected light is totally parallel to the rail and enters the detector.

连接：

1. Choose the “external trigger” of the oscilloscope.

 

1. Connect “base” of the measurement instrument to the external trigger input of the oscilloscope.

 

1. Connect “measure phase” of the measurement instrument to the Channel 1 of the oscilloscope.

 

1. Connect “measure frequency” of the measurement instrument to the Input A of the frequency meter.

调整：

1. Adjust the "trigger" level to make the waveform stable.

 

1. Adjust the horizontal and vertical scales to suitable amplitudes in order to displays only one complete waveform on the screen.

If the whole waveform expands in the x direction to 10 large divisions, then each large division represents 36 degrees of phase change. You can estimate up to 0.1 large divisions.

 之后开始测量：

1. When the measurement begins, first remember the starting position of a characteristic point of the waveform. Then move the prism cart so that the waveform moves.

If you cannot adjust a complete waveform exactly to 10 divisions, you may use the following formula to obtain the phase change.

 

error： 步骤上的 认为， 系统误差。