General Information; Introduction; Equipment Description - HP 5501B Operating And Service Manual

1 GENERAL INFORMATION

1-1.

Introduction

1-2. This Operating and Service Manual contains information required to install, operate, test, adjust,
and service the Hewlett-Packard Model 5501B Laser Head. The information in this manual is
specific to the HP5501B and supplements other publications available for Hewlett-Packard Laser
Transducer products. Also available is the HP5501A Laser Transducer System Manual (HP Part
Number 05501-90028) that describes how to setup, align, and use the laser system to make
interferometer measurements.
1-3. The HP part number of this manual is listed on the title page. Also listed is a microfiche part
number for ordering 4 X 6" microfilm transparencies of this manual. The microfiche package also
includes the latest "Manual Changes" supplement and any pertinent Service Notes.
1-4.

Equipment Description

1-5. The HP5501B Laser Head consists of a thermally-tuned laser tube, control circuits, a reference
receiver, and a high-voltage power supply. The laser head requires ±15 Volt supplies, each with
a minimum capacity of 1 Amp. The HP5501B produces a frequency stabilized laser beam, a
balanced reference output (see paragraph 16), a +15 Volt fused output, and a +5 Volt output.
Diagnostic LED's, mounted on the 5501B's rear panel, provide status information on power
supply input (±15 Volts), fuses, laser output and tuning, and the reference frequency output.
1-6. The 5501B laser beam consists of two linearly polarized and mutually perpendicular (orthogonal)
components separated in frequency by approximately 1.8 MHz. The two components have light
frequencies of F1 and F2. The higher frequency component (F2) is oriented parallel to the laser
base, while the lower frequency component (F1) is perpendicular to the laser base. An optical
receiver inside the HP5501B detects the 1.8 MHz frequency difference and places it at the rear
panel REFERENCE SIGNAL connector as a balanced output (called the REFerence Frequency).
The reference output is one signal used by the external electronics to measure distance traveled.
1-7. During a typical measurement application, the laser beam travels through external optics where
the horizontal and vertical components of the beam are separated. One component travels along
a fixed path and returns to an external optical receiver. The other component travels along the
path (axis) to be measured and then returns to the external receiver. The external receiver
detects the frequency difference between the two components and outputs a signal called the
MEASure Frequency. The MEASure Frequency from the external receiver and the REFerence
Frequency from the laser head are compared by external, customer selected electronics. If the
distance between the external optics is fixed, the MEASure and REFerence frequencies are
equal. As the relative distance between the external optics changes, the MEASure Frequency
changes due to a Doppler frequency shift. This relative change between the MEASure and
REFerence Frequencies is used by the system electronics to compute distance traveled. The
laser transducer system can be configured for computer control of open- and closed-loop
positioning and measuring applications, having single or multiple axes. For more detailed
information, refer to the HP5501A Laser Transducer System manual (HP Part Number 05501-
90028).
1-2
HP5501B
Installation