Coaxial ophthalmoscope arrangement

In a coaxial ophthalmoscope of the type in which the viewing axis is coaxially aligned with a beam of light directed into the eye under examination the improvement comprising:

• light beam generating means for generating a beam of visible light in a first direction along a first axis;
• beam splitter means spaced from said light beam generating means and positioned to intercept said beam of light and reflect a first preselected amount thereof in a second direction, different from said first firection, along a viewing axis, and transmit a second preselected amount of said beam of visible light therethrough along said first axis;
• light trap means spaced from said beam splitter means and comprising a first planar surface means free of light absorbing coating thereon spaced from said beam splitter means and positioned at a predetermined angle to said first axis to receive said second preselected amount of said beam of light transmitted through said beam splitter means, and said light trap means for preventing substantially all of said second preselected amount from reflecting along said viewing axis;
• means for directing said first preselected amount of said beam of light into an eye under examination;
• means for viewing said eye under examination through said beam splitter along said viewing axis;
• wherein a first portion of said first preselected amount of light is reflected from the cornea of said eye under examination through said beam splitter means and toward said means for viewing said eye under examination, and a second portion of said first preselected amount of light is reflected from the retina of said eye under examination through said beam splitter means toward said means for viewing said eye under examination;
• and
• filtering means for selectively filtering out said first portion of said first preselected amount of light.

A light trap means comprising, in combination:

• an optically transparent body member having:
• a first planar surface for receiving a beam of light, and said first planar surface oriented at a first preselected angle to the direction of said beam of light;
• a base planar surface substantially parallel to the direction of said beam of light and intersecting said first planar surface at a first edge;
• an outer planar surface intersecting said base planar surface at a second edge and defining a second preselected angle therewith and intersecting said first planar surface at a third edge to define a third preselected angle therewith;
• and
• a pair of spaced apart substantially parallel planar side surfaces intersecting said base planar surface, said outer planar surface, and said first planar surface.

A light trap means comprising, in combination:

• a pair of optically transparent substantially identical body members, each of said pair of body members having:
• a first planar surface for receiving approximately 50% of a beam of light and said first planar surface at a first preselected angle to the direction of said beam of light;
• a base planar surface substantially parallel to said direction of said beam of light and intersecting said first planar surface at a first edge;
• an outer planar surface intersecting said base planar surface at a second edge to define a second preselected angle therewith and intersecting said first planar surface at a third edge to define a third preselected angle therewith;
• and
• a pair of spaced apart substantially parallel planar side surfaces;
• said base planar surfaces of each of said pair of body members substantially coextensive and contiguous and aligned along said direction of said beam of light.