Light waveform measuring device including a streak camera

• US 5,032,714 A
• Filed: 01/02/1990
• Issued: 07/16/1991
• Est. Priority Date: 04/03/1989
• Status: Expired due to Fees

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Takahashi, Akira, Koishi, Musubu
• Primary Examiner(s): Nelms, David C.
• Application Number:
  US07/460,009
• Time in Patent Office: 560 Days
• Field of Search: 250/458.1, 250/461.1, 250/226, 250/213 R, 250/213 VT, 356/317
• US Class Current: 250/214.0VT
• CPC Class Codes: G01J 11/00 Measuring the characteristics of individual optical pulses or of optical pulse trains
• CPC Class Codes: G01J 2011/005 Streak cameras
• CPC Class Codes: G01J 9/04 by beating two waves of a same source but of different frequency and measuring the phase shift of the lower frequency obtained
• CPC Class Codes: G01N 21/6408 with measurement of decay time, time resolved fluorescence

Abstract

Laser sources produce two light beams which are different in frequency and at least one of which is a pulse beam. The two light beams are subjected to sum frequency mixing in a non-linear optical element and a resultant sum frequency beam is applied to a specimen as an exciting pulse beam. A pulse beam separated from the sum frequency beam and synchronized therewith is detected by a photodetector. A measuring means measures a waveform of fluorescence light emitted from the specimen using an output of the photodetector as a measurement starting reference signal. According to one embodiment, the device operates in a single photon counting mode and the measuring means counts repeatedly an elapsed time from the detection of the measurement start reference signal to the detection of the fluorescence light for every divided section of the elapsed time.

Claims

1. A light waveform measuring device which measures a waveform of light produced from an object in response to an exciting pulse beam, comprising:

light source means for outputting first and second light beams which are different in frequency and at least one of which is a pulse beam;

mixing means for subjecting said first and second light beams to sum frequency mixing;

selecting means for selecting a sum frequency beam from output beams of said mixing means, and applying said sum frequency beam to said object as said exciting pulse beam;

pulse detecting means for detecting a pulse beam which is synchronous with said sum frequency beam from said output beams of said mixing means and producing an output when such a pulse beam is detected; and

measuring means for detecting and measuring said waveform of light produced from said object in response to said exciting pulse beam using said output of said pulse detecting means as a measurement starting reference signal.

2. A light waveform measuring device as claimed in claim 1, wherein said measuring means includes a photodetector for detecting a single photon produced from said object, and said measuring means measures repeatedly a time period which elapses from a time instant that said pulse detecting means produces said output until said photodetector produces an output, to obtain a distribution of said time period as said waveform of light.

3. A light waveform measuring device as claimed in claim 2, wherein said light waveform measuring device is adjusted so as to operate in a single photon counting mode.

4. A light waveform measuring device as claimed in claim 1, wherein said measuring means comprises a streak camera which receives said light from said object to produce photoelectrons and sweeps said photoelectrons using said output of said pulse detecting means as a trigger signal.

5. A light waveform measuring device as claimed in claim 1, wherein said measuring means comprises a sampling type light waveform observing device which receives said light from said object and operates using said output of said pulse detecting means as a trigger signal.

6. A light waveform measuring device as claimed in claim 1, wherein said mixing means comprises a half mirror for combining said first and second light means, and a non-linear optical element for producing said sum frequency beam in response to a combined beam from said half mirror.

7. A light waveform measuring device as claimed in claim 2, wherein said measuring means further includes a time-amplitude converter for converting said time period into a voltage pulse having a height which is proportional to said time period, and a pulse height analyzer for counting said voltage pulse.