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Pentaprism
At present, pentaprism is widely used. Pentaprism (roof-type pentaprism) is a common optical element in SLR cameras, while double pentaprism (two pentaprisms top to top) is used in construction measurement. combined) and a plumb line to mark the correct angle.We are an optical Penta prism manufacturing group in China that offer high-quality prism. If you need this product, please contact us right now!
The principle of pentaprism
Pentaprism, also known as pentagonal prism, is a kind of optical reflection prism, pentaprism is an optical prism with five reflecting surfaces, which can deflect incident light by 90°. The incoming light is reflected twice in the prism, changing the direction by 90°, not only will it not be inverted, but also will not change the handedness of the image. Ordinary right angle prisms will invert the image and change the handedness.
Pentagonal prisms are extremely useful in calibration systems because they can very precisely specify right angles and, respectively, angles of incidence. The ray enters from one side, and after two 270-degree reflections inside the prism, it exits on the other adjacent side.
At present, pentaprism is widely used. Pentaprism (roof-type pentaprism) is a common optical element in SLR cameras, while double pentaprism (two pentaprisms top to top) is used in construction measurement. combined) and a plumb line to mark the correct angle.
The history of pentaprism
In 1948, a manufacturer drew a circle on the top of the camera. East German Zeiss (also called Jena Zeiss, which was a product of the split between the United States and the Soviet Union after World War II) produced the first pentaprism head-up SLR camera Contax S in history. , it finally established the typical structure of the 135 SLR camera, a lens, a mirror, and then a pentaprism to turn the light path, on the one hand, the overhead light path is turned into a head-up view, and on the other hand, the image of the framing is turned left and right. (When looking down and framing, it looks like the left and right are reversed), the most advanced digital SLR cameras are completely indistinguishable from their ancestors in 1948 in terms of the basic structure of the framing.
The structure of the pentaprism
The reflection in the pentaprism is not caused by complete internal reflection. Since the beam enters at less than the critical angle, the two reflective surfaces are coated with reflective materials to create a mirror reflection effect, and the two transmission surfaces are coated with anti-reflective coatings to reduce reflections. The fifth side of the pentaprism is not used optically. The pentaprism used in modern cameras is often coated with a silver film by vacuum coating technology on the reflective surface and covered with a black protective coating to strengthen reflection effect.
Theoretically speaking, the reflective field of view of the pentaprism is 100%, but due to reasons such as cost, interior space and product market positioning, the field of view of most SLR cameras will not be 100% (viewfinder field of view). The rate is also a benchmark for distinguishing professional and quasi-professional bodies. In recent years, under the frenzied cost-cutting practice of manufacturers, there have also been SLR cameras that use five mirrors instead of five prisms to form the optical path. The viewfinder of this camera often Appears dim, not as bright as the pentaprism.
PRODUCT FEATURES:
Prism angle accuracy: conventional≤3'-6', unconventional≤1'-2', parallel≤0.003mm
Dimensional tolerance:controlled within≤0.02mm
Tower difference: the tower difference angle is generally controlled at 3', with a minimum of 1' or better
Surface shape(aperture): mass production can reach 1λ
