Collimation axis error refers to the collimation axis and the horizontal axis of non-orthogonal error during installation of the telescope prone to such errors, depending on the level of quasi-axis error mainly affects the direction of observation.
     1. Impact: As shown, set the correct collimation OA axis, ABDC surface is composed of horizontal, vertical angle α is 0, the actual collimation axis should be OC, there ∠ AOC = C, when the visual only when the quasi-axis to form a OO 'as the axis, ON for the bus, cone angle (180 °-2C) of the cone, the cone bottom of the CND, while the circle with O as the center of a circle AMB compared with the size, the same as with the CND circle. When the vertical angle, when α, N-point in the horizontal plane projection of P, then the MP ⊥ CO ', ∠ NOP = α, ∠ MON = C, ∠ AOP = △ C.
There are: ON * cos ∠ NOP * sin ∠ HOP = HP = MN = ON * sin ∠ MON
Namely: cosα * sin △ C = sinC
Also: △ C, C are very small, sin △ C ≈ △ C, sinC ≈ C
Was: cosα △ C = C, that is, △ C = C / cosα
That is, when collimation axis and the horizontal axis is not orthogonal error of C, instrument awarded a goal when the altitude angle of α, depending on the horizontal axis error on the observed values of the value of △ C = C / cosα, from last type can be be seen, △ C depending on the size of the quasi-difference not only with the size of C, but also with the observation target on the vertical angle α.
     When the equipment is in I (disc left) position, there is error of collimation axis collimation axis of living in the right side of the right, then I awarded goal of horizontal surface observations corrected after: L1 = L-△ C, where L1 for the correct position after the horizontal direction I face value, L for the horizontal I surface observations. Similarly, R1 = R + △ C, where R, R1, respectively Ⅱ (plate right) awarded two horizontal objectives of the observed values and corrected values. Take I and Ⅱ in the number of surface observations, there are observed values of the horizontal direction:
1 / 2 (L1 + R1 ± 180 °) = 1 / 2 (L-△ C + R + △ C ± 180 °) = 1 / 2 (L + R +180 °)
     As can be seen from the above equation in order to I face, Ⅱ surface observations into a few observations as a target value of the horizontal direction, depending on the quasi-axis error can be eliminated its impact, but it is in the horizontal axis, vertical installation of well-dial, etc. results of the case. In other parts to install than the standard case, the collimation axis error will continue to impact, and therefore do everything to remove this error.
    At the same time, we can get 2 △ C = LR ± 180 °, while for α = 0, C = △ C, there were 2C = LR ± 180 °, can be seen from the above equation, the objective of observing a certain level, through the I observed value minus the face value of the method Ⅱ surface observation instruments can be measured twice as bad as the quasi-2C.
    2. Check
    1. Will be fixed to the calibration equipment, and precision leveling table
    2. The machines turned on and are mirror (disk left) awarded collimator infinity objectives, level of dial reading as the HC
    3. The apparatus inverted microscope (plate right) awarded collimator infinity objectives, level of dial readings of HR.
    4. Calculations C = 1 / 2 [(HC-HR) ± 180 °]
    5. If C> 9 ", Zexu calibrated, otherwise no correction.
    3, calibration
    1. The instrument between the telescope and the eyepiece counter-clockwise twist of the cover to open;
    2. Will be fixed on the calibration equipment, and precision leveling table;
    3. First instrument is mirror (disk left) awarded collimator infinity objectives, record the dial readings of the level of HC, the instrument inverted microscope (set right) awarded collimator infinity objectives, record levels of dial readings of HR, and in accordance with C = 1 / 2 [(HC-HR) ± 180 °] calculated C values.
    4. In the inverted position of rotating mirror the level of micro-hands-round, so that the level of dial readings show changes in C / 2, this time looking through the telescope instrument in infinity collimator objective, you will find a small amount of offset, that is C / 2 .
    5. With the correction to adjust the horizontal 2-pin adjustment screw, so that the telescope partition very small amount of movement took place and with the goal of collimator infinity coincide.
    6. C, re-inspection procedures, such as the C value is still exceeded the specified value, then repeat the above calibration steps.
    In particular, note that, with correct needle adjustment, the amount of each of the adjustments can not be great, and the horizontal adjustment screw on the two is very tight or too loose, otherwise over time, partition panels are prone to movement, and thus C values caused by the change, therefore, also need to repeat it at a certain time awarded to C-axis error correction.