Laser Assembly Optics; Reference Receiver; Shutter Mechanism; Assembly/Schematic Locations Of Hp5501B Block Diagram Elements - HP 5501B Operating And Service Manual

Laser head

Table of Contents

8-40. Laser Assembly Optics

8-41.

The laser assembly optics ensures correct laser frequency polarizations and also collimates the

laser beam. When the laser beam leaves the laser assembly, the horizontal component is

polarized parallel to the base of the HP5501B. The vertical component is polarized

perpendicular to the horizontal component. The laser beam is collimated to minimize variations

in beam diameter as it travels away from the laser head.

8-42. Reference Receiver

8-43.

The beam splitters of the A6 Sampler Assembly direct some of the laser light through a second

45° polarizer and onto another photodiode. Because of the polarization orientation, the beam

power after this polarizer varies sinusoidally at the difference frequency of the two laser

frequency components. The beam power at the difference frequency is converted to current by

the photodiode and amplified to TTL levels. The frequency of the TTL output is the reference

frequency. The reference receiver electronics also provide a digital signal called REFERENCE

RECEIVER ON (REF ON) that tells the state machine the laser is working properly

8-44. Shutter Mechanism

8-45.

The exit aperture shutter of the shutter (turret) assembly has three positions. The first blocks the

laser beam entirely; the second allows a small diameter laser beam to exit for optical alignment

purposes; and the third passes the entire laser beam.

8-46. ASSEMBLY/SCHEMATIC LOCATIONS OF HP5501B BLOCK DIAGRAM ELEMENTS

ELEMENT

Control Electronics

Power Amplifier

Warmup Error Amplifier

Subtracting Sample & Hold

Photodiode & Amplifier

Clock and State Machine

Laser Assembly

Sampler Assembly

Reference Receiver

8-47. REAR PANEL LED INDICATORS

8-48.

The diagnostic LED's, mounted on the HP5501B's rear panel, provide status information on

power supply input (±15 Volts), fuses, laser output and tuning, and the reference frequency

output. See Figure 3-2 for a more detailed description of the LED's.

8-12

HP5501B ASSEMBLY

A3 and A4

A1 and A3

A4 and A3

A3 and A6

HP5501B

Service