convergent pencial of rays
会紧光束

• steller field background
• steller illuminance
• steller interferometer
• steller irradiance measurement
• steller light
• steller parallax
• steller photometry
• steller radiation
• stem
• step
• step-and-repeat camera
• step bearing
• step-by-step
• step-by-step account
• step-by-step carry
• step-by-step excitation
• step-by-step process
• step-by-step variable gear
• step-by-step variable speed transmission
• step change
• step function
• step ga(u)ge
• step height interferometer
• step-index fiber
• step-input