D-656 TWO AXIS AUTOCOLLIMATOR
The Model D-656 Two Axis Autocollimator excels in measuring two orthogonal planes because both azimuth and elevation readings are obtained with the same dial. This eliminates the error often introduced by autocollimator barrel rotation when alternating between azimuth and elevation positions. The midsection eyepiece has sufficient eye relief for those who wear glasses; also, eye strain is reduced by the dark field reticle with illuminated target (see above) and the distinct black crosshair filar marked to show azimuth and elevation. Rotating the micrometer dial causes the filar to travel across the field until the proper line bisects the center of the target. No numbers or scales confuse the field of view, but are carried entirely on the micrometer drum. The Model D-656 functions efficiently on optically fiat surfaces and on aluminized surfaces as small as 0.5 inch in diameter.
- Measure both orthogonal planes without adjustment
- 20 arc minute measuring range
- Compact folded design makes alignment easy
- Built-in adjustable mounting base
- Center tilted eyepiece for easy viewin
- Dark field projected reticle and external readout reduce eye fatigue
- Certification of accuracy traceable to NIST
Applications:
The Model D-656 Two Axis Autocollimator measures angles around an X-Y axis or intermediate points between obliquely tilted surfaces. The filar bisection of the target gives a read-out in arc minutes and arc seconds on the adjoining micrometer drum for both azimuth or elevation. Azimuth and elevation adjustment are quickly made with fine thread adjustment screws mounted in base.
Autocollimator functions:
The basic function of an autocollimator is to detect and measure a deviation in the position of a reference reflective surface. The autocollimator projects a collimated beam of light onto a reflective surface. When a deviation in the position of that reflective surface occurs, a deviated beam of collimated light returns to the autocollimator. A direct angular reading autocollimator, such as the Model D-638 Coordinate Autocollimator or the Model D-656 Two Axis Autocollimator, will provide a direct angular measurement of the reflective surface deviation through acquisition and measurement of the deviated return beam angle.
For more theory of operation, please refer to the Principles of Autocollimation Application Note.
Specifications:
| Sensitivity: | 0.1 arc sec | |
| Accuracy: | 0.5 arc sec over 1 arc min, 3 arc sec over 20 arc min (Calibration curve over full range available at nominal cost) |
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| Repeatability: | ±0.2 arc sec or better (standard deviation) |
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| Measuring range: | 20 arc min | |
| Measuring range; @ long distances: | ±10 arc min at 35 ft (10.7 m); ±2 arc min at 125 ft (38.1 m) | |
| Arc seconds scale: | Graduations 0.2 arc sec | |
| Arc minutes scale: | One revolution equals one arc min. Counts the revolutions of seconds scale; graduated from 0 through 20 arc min | |
| Aperture Diameter: | 2.375 inch (60.3 mm) | |
| Eyepiece Magnification: | 12X (24X available) | |
| Focal Length: | 20 inch (508 mm) | |
| Eyepiece Reticle: | Crosshair with elevation line defined "EL" and azimuth line defined "AZ" | |
| Projected Reticle: | Dark field with illuminated concentric circles approximately 2 arc minutes apart around an approximately 10 arc second diameter center dot | |
| Light Source: | Incandescent lamp with D-416, 6 VDC variable power supply 110V/ 60Hz or 220V/ 50Hz | |
| Housing Material: | Aluminum | |
| Base adjustment: | Azimuth: | ±2° |
| Elevation: | ±2° | |
| Overall Dimensions: | Height: | 9 inch (229 mm) |
| Width: | 6 inch (152 mm) | |
| Length: | 12.5 inch (318 mm) | |
| Base Length: | 10.5 inch (267 mm) | |
| Height to Aperture Center: | 3 inch (76 mm) | |
| Finish: | Ivory enamel | |
| Carrying Case: | Hardwood | |
| Instrument Weight: | 21 lbs (9.5 kg) | |
| Shipping Weight: | 40 lbs (18.1 kg) | |
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Optional Accessories:
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Model D-165 High Intensity Light Source. This option may be required when autocollimating off of low reflectivity surfaces or small mirrors.
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Model D-247 Table Instrument Stand
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Model D-416B 220V 50Hz Power Supply
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105-2761-656 Video Camera & Monitor with integral camera power supply. With this option readings become very easy even for unskilled personnel. Repeat readings are more accurate and faster. The camera eliminates any errors from parallax and greatly reduces eye fatigue. This option is easily added to existing Model D-271's
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Support Documentation |
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D-656 Drawing |
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