Porro prism erecting system
波罗镜正像系统

• push fit
• push out
• push-pull
• push-pull amplifier
• push-pull track
• push-pull type
• put in circuit
• putty powder
• pyod
• pyramid
• pyramidal error
• pyramidal error of prism
• pyranometer
• Pyrex
• Pyrex cooling jacktet
• pyrex glass
• pyrheliometer
• pyridine
• pyridine picrate
• pyrocatechol
• Pyroceram
• pyroelectric
• pyroelectric bolometer
• pyroelectric copying process
• pyroelectric crystal