Yes, was thinking about picking one up if I get a chance at one cheap for playing around with, possibly surface plate checking. And those kinds of links are exactly what I was looking for, thank you cameraman.
Yeah no worries , very welcome.
Randomly seeing what's available on line; some folks know what these instruments are worth $$$$$$ +++ , and sometimes you see some pretty good deals on more unusual autocollimators where some work / risk is required.
Davidson Optronics D-600 Comparison Autocollimator
This is from BMI surplus* a "Davidson Optronics D-600 Comparison Autocollimator "
For only $750.00
^^^ Click to enlarge.
But not officially tested and probably have to build various mounts for it.
But the basic technical specs and capability as outlined as follows / blurb to give you an idea of sensitivity versus accuracy (500 mm / 508 mm / 20 inch - focal length).
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This used Davidson D-600 Comparison Autocollimator comes from a working environment but has not been tested. Please call us for more information.
From Manufacturer Website:
- Measure angular differences between two reflecting surfaces to 0.1 arc second
- Readings are not affected by instrument movement
- Extremely simple to check surface plates or machine tool alignment
- Measure about either vertical or horizontal axis
Model D-600 Comparison Autocollimators apply a unique principle of autocollimation to compare and measure small angles with extremely high precision. Specifically, the instrument measures the difference in angle between two reflecting surfaces. A beam of collimated light from the instrument is divided to illuminate a reference mirror and a second mirror whose relative angle is to be determined. The patented design employs a unique arrangement of optical tipping plates coupled to a calibrated micrometer dial, where the relative angle is read when the images are aligned.
Differences in angle of the returning beams can be measured with average repeatability of 1/10 arc seconds, either vertically or horizontally.
The micrometer dial is graduated in 1/10 arc seconds, with each second numbered. One complete revolution of the dial is equal to 10 arc seconds with a total range of 120 arc seconds. Of utmost importance to precision is the fact that instrument movement during reading will only move the images in the field of view; it will have absolutely no effect on the reading. This fact eliminates the rigid mounting and extreme handling care demanded by other instruments, where any motion is translated directly into the micrometer reading.
Manufacturer Specifications:
- Sensitivity: 1/10 arc sec
- Accuracy: 0.5 arc sec
- Focal Length: 20 inch (508 mm)
- Aperture Diameter: 2.375 inch (60 mm)
- Measuring Range: 120 arc sec
- Micrometer Scale: Graduation 1/10 sec One revolution equals 10 sec
- Housing Material: Aluminum
- Overall Dimensions: (L x W x H) 23 x 5.375 x 5.125 inch (584 x 137 x130 mm)
- Finish: Ivory enamel
- Carrying Case: Hardwood
This unit has not been calibrated. Buyer will need to source their own calibration.
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^^^ Just to give you a feel of what autocollimators of different vintages and focal lengths are capable of doing.
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* No affiliation.