Voltage detector using electro-optic material having anti-reflective coatings

• US 4,968,881 A
• Filed: 02/02/1989
• Issued: 11/06/1990
• Est. Priority Date: 04/08/1988
• Status: Expired due to Term

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Tsuchiya, Yutaka, Takahashi, Hironori, Aoshima, Shinichiro, Ooi, Yoshiharu, Takahashi, Mutsuji
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Allen, Stephone B.
• Application Number:
  US07/305,346
• Time in Patent Office: 642 Days
• Field of Search: 250/231 R, 250/231.10, 324/96, 350/164, 350/311, 350/356, 350/374
• US Class Current: 250/231.1
• CPC Class Codes: G01R 15/242 based on the Pockels effect, i.e. linear electro-optic effect
• CPC Class Codes: G02F 1/0311 Structural association of optical elements, e.g. lenses, polarizers, phase plates, with the crystal

Abstract

A voltage detector comprises a light modulator which employs an electro-optic material whose refractive index changes according to the voltage developing in an object to be measured. A transparent anti-reflection film having a refractive index and thickness which are predetermined on the bases of a refractive index of the electro-optic material and a wavelength of incident light is formed on both light entrance and exit surfaces of the electro-optic material.

Claims

1. A voltage detector for detecting a voltage in an object, comprising:

a pulsed light source for emitting incident light pulses;

a light modulator for modulating intensity of said light pulses including an electro-optic material having an entrance surface and an exit surface, a refractive index of said electro-optic material being changed in accordance with said voltage of said object, and on both said entrance surface and said exit surface of said electro-optic material being formed a transparent anti-reflection film with a prescribed refractive index and thickness; and

a photodetector for detecting modulated light pulses and for determining said voltage of said object on the basis of intensity of said modulated light pulses.

2. A voltage detector as claimed in claim 1, wherein said anti-reflection film has a single-layer structure which is adapted for light pulses having a specified wavelength.

3. A voltage detector as claimed in claim 1, wherein said anti-reflection film has a multi-layer structure which is adapted for a light beam having a prescribed range of wavelengths.

4. A voltage detector as claimed in claim 1, said light modulator further comprises:

a polarizer for extracting light pulses with a first predetermined polarization component from said incident light pulses; and

an analyzer for extracting light pulses with a second predetermined polarization component from said light pulses outputted from said electro-optic material to produce said modulated light pulses.

5. A voltage detector as claimed in claim 4, wherein a transparent anti-reflection film with a prescribed refractive index and thickness is formed on both an entrance surface and an exit surface of said analyzer and said polarizer.

6. A voltage detector for detecting a voltage in an object, comprising:

a continuous wave light source for emitting a continuous incident light beam;

a light modulator for modulating intensity of said continuous light beam including an electro-optic material, said electro-optic material having an entrance surface and an exit surface, a refractive index of said electro-optic material being changed in accordance with said voltage to said object, and a transparent anti-reflection film with a prescribed refractive index and thickness being formed on both said entrance surface and said exit surface of said electro-optic material; and

a photodetector for detecting a modulated light beam and for determining said voltage of said object on the basis of intensity of said modulated light beam, said photodetector including a high speed photodetector for detecting said modulated light beam at a high speed and displaying the change of said voltage as a function of time.

7. A voltage detector as claimed in claim 6, wherein said anti-reflection film has a single-layer structure which is adapted for a continuous light beam having a specific wavelength.

8. A voltage detector as claimed in claim 6, wherein said anti-reflection film has a multi-layer structure which is adapted for a continuous light beam having a prescribed range of wavelengths.

9. A voltage detector as claimed in claim 6, wherein said high speed photodetector includes a streak camera.

10. A voltage detector as claimed in claim 6, wherein said high speed voltage detector includes a sampling optical oscilloscope.

11. A voltage detector as claimed in claim 6, said light modulator further including:

a polarizer for extracting a continuous light beam with a first predetermined polarization component from said incident light beam; and

an analyzer for extracting a continuous light beam with a second predetermined polarization component from a light beam outputted from said electro-optical material to produce said modulated light beam.

12. A voltage detector as claimed in claim 11, wherein a transparent anti-reflection film with a prescribed refractive index and thickness is formed on both an entrance surface and an exit surface of both said analyzer and said polarizer.