垂直度盘由主光栅、指示光栅、指示光栅座、轴和轴套组成，在垂直度盘安装过程中会产生竖盘指标差和水平轴倾斜误差。
竖盘指标差是由于固定指示光栅安装不正确引起的，是指当视准轴水平时，垂直度盘读数不为90度。安装好垂直度盘后，将仪器放在仪器墩上，照准与仪器大致同高的平行光管无穷远处的目标，用盘左、盘右观测目标的天顶距。则
盘左：α=90°-L+I；盘右：α=R-270°-I
得I=1/2（L+R-360°）
若指标差I超过规定的限差，则进行校正，校正分为两种：一种是机械校正，一种是通过软件校正。机械校正，松开指示光栅座与支架连接的4个螺钉，旋转调整指示光栅座，再次进行盘左盘右测量计算指标差，直到满足需要为止。
软件校正：启动仪器的指标差校正程序，按显示屏提示，盘左、盘右照准平行光管，提取指标差差值并存储，经上述校正后，仪器显示的角度为校正指标差后的值，即指标处于正确安装位置时的值 。
水平轴倾斜误差是由于支撑水平轴二支架的高度不等高造成的，当水平轴倾斜时会对水平角的测量有很大影响、在竖轴铅直，视准轴也水平轴垂直的前提下：
1.以水平轴中心O为圆心，任意长为半径作球，HH1代表水平轴水平位置，H′H1′代表水平轴倾斜之角时的位置，竖直角度在H1一侧，水平轴绕竖轴旋转时，在各个方位上的倾斜角β是不变的。
2.当水平轴水平时，照准目标T，则垂直照准面是OZTM′，它在水平度盘上读数为M′,如果水平轴倾斜β角，当视准轴指向天顶时，视准轴就不会在正确的OZ位置，而移至OZ′位置，用这样的视准轴去照准目标T时，照准面为倾斜面OZ′TM，在水平度盘的读数为M。
弦长MM′=△β就是水平轴倾斜误差对方向读数的影响。作OZM垂直面，在球面三角形ZTM中，ZT=Z,LZMT=β,TM≈α,LTZM=△β,则由球面垂直角公式：Sin△β=Sinβ/Sinz*Sinα
又因为β和△β为小角度，可得△β=βtgα，这就是水平轴倾斜误差对水平角影响的关系式。对水平轴的倾斜误差的检定采用平、低（高）点法来检定：在室 内选定两个点，一个高于水平视线，一个低于水平视线，且垂直角满足α高=-α低，
当观测高点时:（L-R）高=2L/COSα高+2β*tgα高
当观测低点时：（L-R）低=2L/COSα低+2β*tgα低
因α高=∣α低∣；则β=1/2（C高-C低）COtα
当采用平、高读时，只要将（L-R）平=2C与（L-R）低=2L/ COSα低+2β*tgα低
具体操作根据软件提示，盘耷拉、盘右分别照准水平平行光管，求解视准轴误差和指示差β1，再盘左、盘右照准点平行光管，求解视准轴误差和指标差β2，这时可根据上述公式求得水平轴倾斜误差。
当水平轴倾斜误差过大时，可通过调整垂直度盘上的指示光栅座同支架的相对位置来校正，也可根据软件进行补偿。
 

Vertical dial from the main grating, grating directions, instructions grating seat, shaft and sleeve composed of a vertical dial during the installation process will produce vertical plate index difference and the horizontal axis tilt error.
Index difference is due to vertical plate fixed index grating caused by not properly installed, when a collimation axis level, the vertical dial reading is not 90 degrees. Perpendicularity is installed after-hours, the equipment on the pier on the instrument, and instrument awarded roughly parallel with the high goal of infinity fluorescent tubes, with disc left and right plate target zenith distance observations. Then
Disk Left: α = 90 °-L + I; plate right: α = R-270 °-I
Have I = 1 / 2 (L + R-360 °)
If the index exceeds the limit of poor I poor, then calibrated, calibration is divided into two kinds: one is the mechanical correction, one is corrected by software. Mechanical correction, release the index grating seat bracket connected with the four screws, rotate, adjust the index grating seat, left-disc set again right measurement and calculation of indicators is poor, until you meet the needs far.
Software Calibration: Start poor indicators of the instrument calibration procedures, display tips, plates left plate collimator awarded the right to extract and store the difference between poor indicators, after the correction, the instrument calibration target shown in perspective after the poor value, which is in the correct installation position indicator values.
The horizontal axis tilt error is due to the horizontal axis supported by two bracket caused by the height of contour, when the horizontal axis is tilted horizontal angle measurement will have significant impacts on the vertical axis vertical, depending on the quasi-axis perpendicular to the horizontal axis is also the premise of follows:
1. To the horizontal axis center O as the center and radius for an arbitrary length of the ball, HH1 on behalf of the horizontal axis horizontal position, H'H1 'on behalf of the horizontal axis when the tilt angle of the position, the vertical angle of the side of the H1, the horizontal axis around the vertical axis rotation in all directions on the tilt angle β is constant.
2. When the horizontal axis level, awarded target T, then the vertical side is awarded OZTM ', it is in the horizontal dial on the reading of M', if the horizontal axis tilt angle β, when the subject when the semi-axis pointing to the zenith, depending on the Quasi-axis of the OZ would not be in the correct location, but moved to OZ 'position, the use of such targets, as awarded to the quasi-axis T, awarded for the inclined plane surface OZ'TM, at the level of dial readings of M.
Chord MM '= △ β is the horizontal axis tilt error on the direction of the impact of reading. For OZM vertical, in the spherical triangle ZTM in, ZT = Z, LZMT = β, TM ≈ α, LTZM = △ β, by the spherical vertical angle formula: Sin △ β = Sinβ / Sinz * Sinα
And because β and △ β for small angle, the available △ β = βtgα, this is the horizontal axis tilt error of the impact of relationship on the horizontal angle. On the horizontal axis tilt error of the test with flat, low (high)-point method to test: In the room selected two points, one above the level of attention, one below the level of attention, and the vertical angle to meet the high α =- α low ,
When observing the high points: (LR) high = 2L/COSα high +2 β * tgα high
When the observation time low: (LR), Low = 2L/COSα low +2 β * tgα low
Due to the high α = | α low |; while β = 1 / 2 (C high-C low) COtα
When using ping, a high reading, as long as the (LR) level = 2C and the (LR), Low = 2L / COSα low +2 β * tgα low
According to the software prompts the concrete operation, plates droop, and plates were awarded the right level of parallel fluorescent tubes, solving collimation axis error and direction deviation β1, and then set the left and right plate awarded points collimator, solving collimation axis error and indicators of poor β2 this time can be obtained under the formula the horizontal axis tilt error.
When the horizontal axis tilt error is too large, it can dial by adjusting the vertical direction on the seat with the grating to correct the relative position of the stent can also be compensated according to the software.