1、 FORD LABORATORY TEST METHOD BO 120-03 Date Action Revisions 2001 03 28 Revised Editorial no technical change A. Cockman 1991 08 27 Printed copies are uncontrolled Page 1 of 4 Copyright 2001, Ford Global Technologies, Inc. DISTORTION IN FLAT MIRRORS Application This procedure is a laboratory test me
2、thod used to determine the presence of distortion in inside and outside flat mirror blanks and mirror assemblies. Apparatus Required Test Fixture With circular test pattern mounted - see Figure 2. Camera Type 35 mm SLR Lens Type 35 mm f/2 wide angle - Nikon, Minolta, Cannon or equivalent. Optical Co
3、mparator Micro VU Model H-14, or equivalent. Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/- 2 C and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unle
4、ss otherwise specified. Procedure 1. Mount the mirror test piece onto the distortion test fixture, see Figure 1. 2. Obtain a sharp, clearly focused image, and photograph the reflected image, see Figure 2. The aperture should be set on the smallest aperture setting (f22 for the Nikon FG). The shutter
5、 speed should be set on A for automatic, or P for program depending on the model. 3. Mount the developed negative between two glass plates on the optical comparator to maintain flatness of the negative. FORD LABORATORY TEST METHOD BO 120-03 Page 2 of 4 Copyright 2001, Ford Global Technologies, Inc.
6、4. Align the negative on the optical comparator slide table to obtain a clearly focused screen image. 5. Using the innermost circle on the circular test pattern, see Figure 2, as the setup reference, locate and zero out the origin point. 6. Starting with the largest completely contained circle, obta
7、in radius measurements for the eight intersecting points. 7. Calculate the average radius (Rn) by summing the eight individual readings and dividing this total by eight: Rn = R1 + R2 +R8 8 8. Using the minimum (Rmin) and maximum (Rmax) radius values measured on the mirror test piece to calculate dis
8、tortion (E) as follows: E = Rn - Rmin x 100 Rn E = Rmax - Rn x 100 Rn The larger value of the two distortion (E) values obtained is the distortion value of that circle. 9. Repeat Steps 7 and 8 for each complete circle shown on the negative. 10. Irregular strains (distortion) found on the largest con
9、tained concentric scale or any scale within, shall be measured and the percent recorded according to Step 8. 11. The highest percent recorded found on the concentric circles is the distortion amount for the test mirror. 12. Distortion Percentages Allowable. A. Exterior Mirrors +/- 3 % B. Interior Mi
10、rrors . Prismatic (non-parallel) +/- 2 % . Sunvisor Vanity Mirror 3 maximum Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD BO 120-03 Page 3 of 4 Copyright 2001, Ford Global Technologies, Inc. DISTORTION IN FLAT MIRRORS Figure 1 FORD LABORATORY TEST METHOD BO 120-03 Page 4 of 4 Copyright 2001, Ford Global Technologies, Inc. DISTORTION IN FLAT MIRRORS Figure 2
