4m Victor Blanco telescope reflectometry data

 

A/ PRIMARY MIRROR:

AUGUST 00 - NOW: reflectivity and scattering.

The measurements were interrupted between November 00 and February 01. Monthly variation rates (over the last 8 months) are: R -0.34% and BRDF(-15) +0.24%. The scatter in the reflectometry plot since February is not well understood, although it might be partly due to the summer seasonal effect (high humidity and thus unstable measuring conditions?).

 

FEBRUARY 01: in-situ washing. Iris reflectometry and BRDF data before/after wash was respectively:

 

AUGUST 00: Aluminizing. Iris Reflectometry and BRDF data before/after the coating was respectively:

Before the coating process started, we noticed a strong reflectivity discrepancy between the Minolta and Iris measurements, of the order of 10% (Iris: 71.7% vs. Minolta: 81.5% at 530nm), which becomes much less for the fresh Aluminium (Iris: 93.0% vs. Minolta: 93.6%).

 

AUGUST 98 - AUGUST 00: regular CO2 cleaning (twice per month)

All data taken with the Minolta. See the plots corresponding to the entire period: reflectivity and scattering.

Yearly variation rates are R -2.5% and SC +2.0%, in agreement with what is measured at the 1.5m. A seasonal trend seems to show up, as is the case for the 1.5m.

Below is a table of the numerical data. In parenthesis (last column) is the number of points sampled on the mirror for each result. Each point on the mirror is sampled 3 times (averaged by the reflectometer). On some dates (like 23Dec98), we also indicate the variations (+/-) in the data. For the first row, replace "before/after CO2 cleaning" by "before/after Al". The case "before Al" means the mirror was CO2 cleaned and measured just before realuminizing.

From 17 April 99 to August 00, we sampled the same 3 points marked on the mirror (the sampling points were random up to that date). On 18 Sept 99, we changed the edge sampling point.

 

DATE

% Reflectivity

before CO2

cleaning

% Reflectivity

after CO2

cleaning

% Scattering

before CO2

cleaning

% Scattering

after CO2

cleaning

Elapsed time (week) between new Al and CO2

 

400nm

700nm

400nm

700nm

400nm

700nm

400nm

700nm

 

7-Aug-98

81.68

78.56

93.88

89.6

8.32

8.75

0.58

0.33

new aluminium

25-Aug-98

92.6

88.83

92.82

89.16

0.70

0.61

0.73

0.55

2 (1)

10-Sep-98

91.99

88.55

92.88

89.05

0.91

0.73

0.73

0.56

4 (1)

30-Sep-98

92.33

88.53

92.34

88.64

1.12

0.86

0.92

0.73

7 (1)

14-Oct-98

93.59

88.71

93.83

88.68

0.93

0.82

0.78

0.66

9 (1)

29-Oct-98

91.81

88.66

90.97

88.22

0.69

0.61

0.94

0.70

11 (1)

12-Nov-98

90.96

88.06

90.45

87.96

1.09

0.95

1.12

0.83

13 (1)

26-Nov-98

91.19

87.75

90.4

87.31

1.40

1.21

1.55

1.07

15 (2)

12-Dic-98

90.87

87.45

91.28

87.87

1.94

1.45

1.1

0.92

17 (3)

23-Dic-98

+/-

92.57

0.51

88.33

0.30

92.69

0.78

88.51

0.39

1.30

0.19

1.19

0.09

1.20

0.25

1.00

0.21

19 (4)

10-Jan-99

+/-

90.78

1.83

87.2

1.19

91.58

1.02

87.96

0.40

1.83

0.60

1.56

0.19

1.56

0.20

1.29

0.14

21 (4)

23-Jan-99

90.8

87.03

90.95

87.55

2.29

2.03

2.04

1.52

23 (3)

5-Feb-99

91.11

87.59

91.41

87.76

1.92

1.64

2.02

1.55

25 (3)

19-Feb-99

89.94

86.42

90.3

86.67

2.86

2.59

2.68

2.35

27 (3)

6-Mar-99

89.51

86.32

89.82

86.61

2.98

2.42

3.18

2.45

29 (3)

19-Mar-99

90.25

86.94

90.48

87.04

2.75

2.19

2.68

2.12

31 (3)

3-Apr-99

+/-

89.62

1.03

86.23

0.45

90.31

0.77

86.51

0.23

3.62

0.81

2.9

0.39

3.15

0.07

2.77

0.10

33 (3)

17-Apr-99

90.4

86.93

90.55

87.14

2.88

2.25

2.75

2.00

35 (3)

1-May-99

89.85

87.07

88.88

85.82

2.6

2.02

2.82

2.09

37 (3)

15-May-99

89.79

86.85

89.81

86.97

2.95

2.15

2.87

2.12

39 (3)

30-May-99

89.45

86.69

89.75

86.92

2.94

2.2

2.86

2.06

41 (3)

13-Jun-99

89.83

87.01

89.69

87.05

2.76

2.04

2.92

2.07

43 (2)

10-Jul-99

89.7

86.78

89.47

87.14

-

-

2.81

1.99

47 (2)

23-Jul-99

89.48

86.56

89.74

87.06

2.99

2.15

2.91

2.07

49 (2)

08-Aug-99

88.35

86.55

88.51

86.62

3.0

2.17

3.02

2.14

51 (2)

22-Aug-99

88.82

86.31

88.69

86.3

3.12

2.29

3.01

2.15

53 (2)

4-Sep-99

89.3

86.4

87.89

85.31

3.15

2.25

3.68

2.45

55 (2)

18-Sept-99

89.6

86.37

89.2

86.24

2.95

2.32

3.15

2.38

57(3)

3-Oct-99

88.56

85.61

88.87

86.02

3.21

2.47

3.36

2.43

59 (3)

15-Oct-99

89.9

87.01

89.79

86.89

2.83

2.1

3.13

2.29

61 (3)

30-Oct-99

88.91

86.09

89.23

86.42

3.22

2.46

3.24

2.35

63 (3)

12-Nov-99

88.72

85.97

88.77

86.08

3.38

2.57

3.33

2.47

65 (3)

29-Nov-99

87.66

85.26

87.85

85.36

4.36

3.35

4.27

3.21

67 (3)

10-Dec-99

87.83

85.22

87.48

85.2

4.11

3.23

4.24

3.11

69 (3)

23-Dec-99

87.67

85.06

88.12

85.43

4.82

3.64

4.42

3.31

71 (3)

7-Jan-00

85.67

83.43

86.32

83.94

       

no cleaning (interp)

22-Jan-00

83.67

81.8

84.51

82.44

7.43

6.01

7.22

5.77

75(3)

5-Feb-00

83.49

81.88

84.04

82.31

7.50

5.95

7.29

5.67

77 (3) interpolated

22-Feb-00

83.31

81.96

83.57

82.18

7.57

5.89

7.36

5.57

79 (3) interpolated

3-Mar-00

83.12

82.06

83.1

82.04

7.64

5.82

7.44

5.48

81 (3)

17-Mar-00

82.36

81.18

82.95

81.92

8.48

6.56

8.05

5.93

83 (2)

31-Mar-00

83.04

81.6

83.2

81.73

7.93

5.96

8.02

6.05

85 (3)

13-Apr-00

82.39

80.99

82.27

81.02

8.51

6.37

8.60

6.34

87(3)

30-Apr-00

82.91

81.88

83.03

82.13

8.34

5.95

8.13

5.75

89 (3)

10_may-00

81.02

79.8

81.11

80.67

10.18

7.99

9.68

7.03

90 (2)

27-May-00

82.82

81.87

82.76

81.89

8.02

5.93

7.71

5.70

91 (3)

11-June-00

82.22

81.04

81.98

81.35

8.81

6.79

8.85

6.45

93 (3)

23-June-00

               

No cleaning

6-July-00

81.88

81.26

81.82

81.17

8.68

6.28

8.86

6.44

97 (3)

22-Jul-00

80.76

80.58

82.31

81.41

9.39

6.73

8.24

6.16

99 (3)

22-AGOGO-00

100

100

100

100

100

100

100

100

99 (3)

Here are efficiency plots of the CO2 cleaning: reflectivity and scattererometry. Average gain per cleaning session is R+0.36% and SC-0.28% in the visible.

 

AUGUST 98: see the plots for before washing and after realuminizing (note: the mirror had not been cleaned at all since early 1997). Data with the Minolta.

 

2/ SECONDARY MIRRORS:

  • F/8 M2: last aluminized on 31 January 01. Iris reflectometry and BRDF data before/after coating was respectively:
  •  

     

    Last update: 2 July 02