| 摘要 |
PURPOSE:To enable quantitative measurement of an electrostatic image with a high resolving power, by detecting an electric field based on a charge of the electrostatic image with a light modulation cell as intensity of light. CONSTITUTION:An opposed electrode 5 and a light modulation cell 6 are arranged above an object 1 to be measured and an electric field chopping means 20 is arranged between the cell 6 and the object being measured. Under the application of an alternating electric field formed by an electrostatic image 4, the electrode 5 and the means 20, an optical fiber 8a for incidence is passed through the cell 6 and light is made incident and picked up from a photodetector 9 through an optical fiber 8b for emission. Electric field based on a charge of the electrostatic image 4 is provided to the cell 6 being chopped and the intensity of light passing through the cell 6 varies with the electric field. In other words, the amount of the charge is converted into an an optical signal. As variation of the optical light corresponds to the amount of the charge, light from the cell 6 is picked up from the detector 9, thereby enabling quantitative measurement of the charge of the electrostatic image. |
