Voice monitoring system using laser beam

A voice monitoring system using laser beam for monitoring voice within a room from an outside of the room, the system comprising:

• a laser transmitter (100) for irradiating a laser beam (B1) of invisible wavelength band toward a predetermined target (410) to be monitored;
• and
• a laser receiver (200) for converting a positional change of a reflected beam (B2) from the target (410) into an electric signal and extracting a voice band component from the electric signal to output it,
• wherein the laser receiver (200) includes:
• a CCD camera (216) having a sensitivity for a wavelength of the laser beam (B1);
• a target display unit (213) for displaying an image taken by said CCD camera (216);
• a positional change detecting unit (218, 220) for converting a positional change of the reflected beam (B2) from the target (410) into an electric signal;
• a sound circuit (219) for extracting a voice band component from said electric signal;
• an optical device (P1, 217) for selectively forming a first path for guiding the reflected beam (B2) from the target (410) to said CCD camera (216) and a second path for guiding the reflected beam to said positional change detecting unit (218, 220);
• and
• an installation state adjustment device (230) for adjusting a n installation state of the laser receiver (200).

A voice monitoring system using laser beam for monitoring voice within a room from an outside of the room, the system comprising:

• a laser transmitter (100) for irradiating a laser beam (B1) of invisible wavelength band toward a predetermined target (410) to be monitored;
• and
• a laser receiver (200) for converting a positional change of a reflected beam (B2) from the target (410) into an electric signal and extracting a voice band component from the electric signal to output it,
• wherein the laser receiver (200) includes:
• a knife edge (220) provided along an optical path of the reflected beam (B2) from the target (410) for shielding a portion of said reflected beam;
• a shielding position adjustment device (221) for adjusting a shielding position of said knife edge (220);
• and
• a light receiving element (218) to receive light flux of the reflected beam (B2) which has not been shielded by the knife edge (220) and to output an electric signal corresponding to energy of received light flux;
• thus to convert a positional change of the reflected beam into an electric signal.

A voice monitoring system using laser beam for monitoring voice within a room from an outside of the room, the system comprising:

• a laser transmitter (100) for irradiating a laser beam (B1) of invisible wavelength band toward a predetermined target (410) to be monitored;
• and
• a laser receiver (200) for converting a positional change of a reflected beam (B2) from the target (410) into an electric signal and extracting a voice band component from the electric signal to output it,
• wherein the laser transmitter (100) includes:
• a CCD camera (121) having a sensitivity for a wavelength of the laser beam (B1), an optical axis of said CCD camera being adjusted so that images of the target (41) and a laser spot (Q) formed on the target can be taken;
• and
• a target display unit (113) for displaying said images taken by the CCD camera (121).