THORLABS LNR502E, User Manual

Page: 17 / 45

Rev A Apr 2020
Page 15
Chapter 4 Operation
4.2.3 Calculating the EncoderConst Value
Each stage has a specific constant for converting encoder counts to microsteps. For the LNR50SE stage, this value is
4292282941.
For example
Encoder resolution = 100 nm
Stepper resolution = 409600 microsteps/turn/mm
= 2.44 nm per step
Therefore no. of µsteps per encoder count = 100 nm/2.44 = 40.96.
The chip inside the controller uses 16.16 bit format, where 16 bits represent the integer and 16 bit are for the fraction.
Interger part 40 = Hex28 = 0X0028
Fraction part 0.96/1/65536 = 62914.56 = F5C3
Therefore EncoderConst value = 0028F5C3
For negative values, we must find the 2s compliment value…
28F5C3 = 0000 0000 0010 1000.1111 0101 1100 0011
2s comp = 1111 1111 1101 0111.0000 1010 0011 1100 + 1
= FFD7.0A3D
4.3 Mounting Equipment to the Stage
Thorlabs manufacture a variety of fibre chucks, holders and fixtures to fit the linear stage. All of these accessories are mounted
to the stage via a top platform, see Fig. 4.6.
Fig. 4.6 Top platform
Caution
The weight attached to the moving platform must not exceed 10 kg.
Do not apply excessive forces to the moving platform.
100 (3.9)
square
25.0
(1.0)
25.0
(1.0)
50 (2")
76 (2.99)
13 holes threaded M6
(1/4-20 UNC) thru
2 holes Ø 11.0 (0.43) thru
all dimensions in mm (inches)