Binocular capable of measuring distance and prism module thereof

A prism module, comprising:

• a first prism comprising a first surface, a second surface and a third surface;
• a roof prism comprising a roof surface and a fourth surface adjacent to the second surface;
• a second prism comprising a fifth surface, a sixth surface adjacent to the third surface, and a seventh surface;
• and
• a third prism disposed higher than the second prism;
• wherein the third prism comprises a light access surface, a first reflecting surface and a second reflecting surface, and the light access surface is partly adjacent to the seventh surface;
• wherein a baseline is configured to pass through the first and the second surfaces of the first prism and the fourth surface of the roof prism;
• wherein a light source is disposed above the second prism, near a side of the third prism, and adjacent to the first and the roof prisms;
• wherein the light source is configured to emit a first light beam;
• wherein the first light beam enters the third prism, is reflected by the third prism, enters the second prism through the seventh surface, passes through the sixth surface of the second prism, enters the first prism through the third surface, is reflected by the second surface of the first prism, and leaves the prism module;
• wherein the first light beam leaving the prism module is parallel to the baseline.