Electronic distance meter

An electronic distance meter comprising:

• a sighting telescope optical system having an objective lens for sighting an object;
• an optical distance meter including a light-transmitting optical system for transmitting a measuring light toward said object on an optical axis of said objective lens therealong;
• and
• a diffraction mask having at least one diffraction aperture which causes diffraction fringes on the measuring light passed therethrough.

An electronic distance meter comprising:

• a sighting telescope optical system having an objective lens for sighting an object;
• an optical distance meter which includes a light-transmitting optical system for transmitting a measuring light toward said object via said objective lens, and a light-receiving optical system for receiving a portion of said measuring light which is reflected by said object;
• a mode selecting device for switching between a distance measuring mode and a pointer mode;
• and
• a rotary disk positioned in said light-transmitting optical system, said rotary disk having a rotational axis extending parallel to an distance-measuring optical path;
• wherein said rotary disk is provided with a diffraction mask and a light-shield mask at different radius positions from the rotational axis of the rotary disk, said diffraction mask having at least one diffraction aperture for causing diffraction fringes on the measuring light passed therethrough, said light-shield mask including at least one translucent portion for defining a beam profile of said measuring light,
• wherein said translucent portion comprises a filter having an uneven density, light transmittance of a central portion of the filter being greater than light transmittance of a peripheral portion of the filter,
• wherein said rotary disk is rotated to insert said diffraction aperture into said distance-measuring optical path when said pointer mode is selected by said mode selecting device, and to insert said translucent portion into said distance-measuring optical path when said distance measuring mode is selected by said mode selecting device, and
• wherein a locus of the center of said diffraction aperture upon rotating said rotary disk intersects said distance-measuring optical path while a locus of the center of said translucent portion upon rotating said rotary disk is deviated from said distance-measuring optical path.

An electronic distance meter comprising:

• a sighting telescope optical system having an objective lens for sighting an object;
• an optical distance meter which includes a light-transmitting optical system for transmitting a measuring light toward said object via said objective lens, and a light-receiving optical system for receiving a portion of said measuring light which is reflected by said object;
• a mode selecting device for switching between a distance measuring mode and a pointer mode;
• and
• a rotary disk positioned in said light-transmitting optical system and having a rotational axis extending parallel to an distance-measuring optical path;
• wherein said rotary disk is provided with a diffraction mask and a light-shield mask at same radius positions from the rotational axis of the rotary disk, said diffraction mask having at least one diffraction aperture for causing diffraction fringes on the measuring light passed therethrough, said light-shield mask having at least one translucent portion for defining a beam profile of said measuring light,
• wherein a central ray of said measuring light incidents upon the center of said diffraction aperture or the center of said translucent portion in accordance with rotational position of said rotary disk,
• wherein said translucent portion comprises a filter having an uneven density, light transmittance of a central portion of said filter being greater than light transmittance of a peripheral portion of said filter, and
• wherein said electronic distance meter further comprises:
• a mask driver which rotates said rotary disk to insert said translucent portion into said distance-measuring optical path when said distance measuring mode is selected by said mode selecting device, and to insert said diffraction aperture into said distance-measuring optical path when said pointer mode is selected by said mode selecting device;
• and
• a controller which actuates said mask driver to rotate said rotary disk so that the center of said translucent portion deviates from said central ray of said measuring light if a measuring light which is reflected by said object is not received enough by said light-receiving optical system when in said distance measuring mode.

An electronic distance meter comprising:

• a sighting telescope optical system having an objective lens for sighting an object;
• an optical distance meter which includes a light-transmitting optical system for transmitting a measuring light toward said object via said objective lens, and a light-receiving optical system for receiving a portion of said measuring light which is reflected by said object, said measuring light having an elliptical beam profile;
• a mode selecting device for switching between a distance measuring mode and a pointer mode;
• and
• a rotary disk positioned in said light-transmitting optical system and having a rotational axis extending parallel to an distance-measuring optical path;
• wherein said rotary disk is provided with a diffraction mask and a light-shield mask at different radius positions from the rotational axis of the rotary disk, said diffraction mask having at least one diffraction aperture for causing diffraction fringes on the measuring light passed therethrough, said light-shield mask having an arc-shaped translucent portion which intercepts opposite ends of said elliptical beam profile of the measuring light in a direction of a major axis of said elliptical beam profile,
• wherein said arc-shaped translucent portion comprises a filter having an uneven density, light transmittance of said filter decreases in radical directions from an approximate center of said filter toward opposite edges thereof, light transmittance of said filter also varying in a circumferential direction of said rotary disk,
• wherein said rotary disk is rotated to insert said diffraction aperture into said distance-measuring optical path when said pointer mode is selected by said mode selecting device, and to insert said arc-shaped translucent portion into said distance-measuring optical path when said distance measuring mode is selected by said mode selecting device, and
• wherein a locus of the center of the diffraction aperture upon rotating the rotary disk intersects said distance-measuring optical path, while a locus of the center of the translucent portion upon rotating the rotary disk is deviated from the distance-measuring optical path.